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MLT immunology > Unit 2 > Flashcards

Unit 2 Flashcards

1
Q

What is another name for antibody?

A

Immunoglobulin

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2
Q

What is an immunoglobulin?

A

Globular proteins (glycoproteins) that play a role in immunity

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3
Q

What is the composition of immunoglobulins?

A

86-98% polypeptides
2-14% carbohydrates

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4
Q

What percentage of plasma proteins are immunoglobulins?

A

20%

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5
Q

Describe serum protein electrophoresis procedure

A

①serum is placed on a agarose gel
②electric current applied to separate the proteins

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6
Q

What pH does electrophoresis separates most serum proteins by size and change?

A

8.6

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7
Q

What do the results of electrophoresis appear as?

A

Five bands

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8
Q

What are the slowest moving protein?

A

Immunoglobulins

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9
Q

What band contains the most antibody activity?

A

Gamma band

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10
Q

What are the 5 classes of immunoglobulins?

A

IgG
IgM
IgD
IgE
IgA

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11
Q

Describe the two dimensional form of IgG

A

-Two large peptide chains (heavy chains) (unique)
- two small peptide chains (light chains) (kappa or lambda)

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12
Q

What is the approximate molecular weight of the heavy chains?

A

50,000

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13
Q

What is the approximate molecular weight of light chains?

A

22,000

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14
Q

How do the kappa and lambda light chains differ?

A
  • Differ by just a few amino acid substitutions along their length
  • No functional difference
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15
Q

What are heavy and light chains held together by?

A

-Disulfide bonds (S-S)
-hydrogen bonds
-hydrophobic forces
-electrostatic attractions

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16
Q

What is the structural unit of all the immunglobulin classes?

A

Tetrapeptide structure

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17
Q

What has sequencing of the amino acids in the heavy and light chains revealed?

A

That each chain has a single variable region and one or more constant regions

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18
Q

Where is the variable region of immunoglobulin located?

A

In the first 110 amino acids of the molecule at the amino terminal

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19
Q

Describe the variable region of an immunoglobulin

A

-unique to each antibody
-allows the molecule to bind specifically to a particular antigen

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20
Q

Where is the constant region of the immunoglobulin located?

A

From amino acid 111 to the carboxyl terminal

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21
Q

Describe the constant region of an immunoglobulin

A
  • are they same in each immunoglobulin class/subclass
    -responsible for the biological functions that play a role in immune defense against an antigen
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22
Q

What are the 3 constant regions of an immunoglobulin?

A

CH1
CH2
CH3

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23
Q

What are CH2 and CH3 responsible tor?

A

For binding to complement and Fc receptors on phagocytic cells

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24
Q

What are the protolytic enzymes?

A

Pepsin and papain

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25
Q

Describe papain

A
  • Cleaves the IgG molecule below the set of the disulfide bonds that holds the two heavy chains together, resulting in formation of 3 fragments: 2 Fab fragments and1 Fc fragment
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26
Q

Describe Fab fragments

A

-each have one light chain and one half of a heavy chain
- Located at amino-terminal end of the molecule
- both are identical
- have antigen-binding capability

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27
Q

Describe the Fc fragment

A
  • Consists of the carboxyl-terminal halves of two heavy chains held together by disulfide bonds
  • spontaneously crystallizes at 4°C
    -does not bind antigen
  • contain constant regions CH2 and CH3*
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28
Q

Describe pepsin

A
  • Cleaves IgG at the carboxyl- terminal side of the interchain disulfide bonds
    -2 fragments: F(ab’)2 fragment and Fc’
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29
Q

Describe the F(ab’)2 fragment

A
  • Molecular weight of 100,000 daltons
  • contains all the antigen- binding ability in pepsin
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30
Q

Describe Fc’ (fragment of pepsin)

A
  • In carboxyl- terminal portion of the molecule which is disintegrated into several smaller pieces
    -has no biological activity
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31
Q

What is the hinge region?

A

-The segment of heavy chain located between the CH1 and CH2
-rich in hydrophobic residues
-high proline content that allows for flexibility

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32
Q

Why is flexibility important in the hinge region of immunoglobulin?

A
  • Lets the two antigen binding sites operate independently and engage in angular motion relative to each other and to the Fc stem
    -initiation of complement cascade
    -binding to cells with specific receptors for the Fc portion of molecule
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33
Q

Which immunoglobulin classes have hinge region?

A

IgG
IgD
IgA

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34
Q

Why do IgM and IgE have flexibility even though they do not have a hinge region?

A

CH2 are paired in such a way as to confer flexibility to the Fab arms

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35
Q

What do immunoglobulins contain?

A

4 polypeptide chains
Carbohydrate portion

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36
Q

Where is the carbohydrate portion of immunoglobulins located?

A

Between the CH2 domains of the two heavy chains

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37
Q

What are the functions of the carbohydrate portion of immunoglobulins?

A

①increasing solubility of immunoglobulin
②provide protection against degradation of molecule
③enhancing functional activity of Fc domains ( most important)

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38
Q

What are the 3 antigenic determinants?

A

Isotype
Allotype
Idiotype

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39
Q

Describe isotypes

A
  • Unique amino acid sequences that are common to all immunoglobulins of given class/subclass
    -identical in all individuals of given species and differ from one species to another
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40
Q

What are isotypes comprised of?

A

Constant regions of the heavy chains that are unique to each immunoglobulin class and give each type its name

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41
Q

How can antibodies to human isotypes be prepared?

A

By immunizing animals with human serum

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42
Q

What are allotypes?

A
  • Minor variations of amino acid sequences that are present in some individuals of the same species but not others
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43
Q

Where classes do allotypes occur in?

A
  • four Ig classes
    -one IgA subclass
  • lambda light chain
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44
Q

Where are allotypes located an an immunoglobulin?

A
  • Found in the constant region
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45
Q

What are idiotypes?

A

-The variable portion of each immunoglobulin chain are unique to a specific antibody molecule
- essential to the formation of the antigen binding site

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46
Q

Where are idiotypes of the immunoglobulin located?

A

At the amino-terminal ends of both heavy chains and light chains

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47
Q

What is the predominant immunoglobulin in humans?

A

IgG

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48
Q

What is the percentage of total serum immunoglobulins that are IgG?

A

70-75%

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49
Q

What is the normal concentration of IgG?

A

800-1600 mg/dl

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50
Q

What immunoglobulin class has the longest half-life?

A

IgG

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51
Q

How long is the half-life of IgG?

A

23 days

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52
Q

Describe structure of IgG

A
  • Monomer
  • consists of one tetrapeptide unit
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53
Q

What is the molecular weight of IgG?

A

150,000

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54
Q

What is the sedimentation coefficient of IgG

A

7S

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55
Q

What is sedimentation coefficient?

A
  • Number of Svedberg units
  • measure of the rate by which the molecule sediments is a high-speed ultracentrifuge, and the S- value reflects the molecular weight of the molecule
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56
Q

What are the 4 major subclasses of IgG?

A

IgG1
IgG2
IgG3
IgG4

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57
Q

What is the composition of the IgG subclasses?

A

IgG1→ 66%
IgG2→ 23%
IgG3→7%
IgG4→ 4%

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58
Q

What are IgG1 and IgG3 produced in response to?

A

protein antigens

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59
Q

What are IgG2 and IgG4 associated with?

A

Polysaccharide antigens

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60
Q

What immunoglobulins can cross the placenta?

A

All subclasses in IgG except IgG2

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61
Q

What are the major functions of IgG?

A

①The CH2 region is able to bind to complement
② important mediator of opsonization
③ participates in antibody- dependent cellular cytotoxicity
④ ability to bind to bacterial toxins and viruses and neutralize their activity
⑤ can cross placenta
⑥ agglutination reactions and precipitation takes place in vitro.

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62
Q

What does activation of complement result in?

A

In an enhanced inflammatory response and destruction of foreign cells such as bacteria

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63
Q

What is the most efficient subclass of IgG to bind complement? Why?

A

IgG3 →it was the largest hinge region and the largest number of interchain disulfide bonds

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64
Q

What is the 2nd most efficient subclass of IgG to bind complement?

A

IgG1

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65
Q

What is opsonization?

A
  • The coating of a foreign antigen that leads to enhanced phagocytosis
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66
Q

Why are IgG1 and IgG3 are particularly good opsonins?

A

They bind most strongly to Fc receptors

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67
Q

Describe IgG participating in antibody- dependent cellular cytotoxicity (ADCC)?

A

-IgG binds to Fc receptors on the surface of marophrages, monocytes, neutrophils, and NK cells
- binding triggers the release of enzymes by the cells, which destroy the antigen extracellularly

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68
Q

Why are IgG efficient at - its ability to bind to bacterial toxins and viruses and neutralize their activity?

A

Has a high diffusion coefficient that allows it to enter extravasular spaces more readily than the other immunoglobulin types

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69
Q

Why is IgG able to cross the placenta?

A

Because the placenta possesses receptors for the Fc region of IgG molecules, which take up the antibodies by receptor- mediated endocytosis and transport them to the fetal blood.

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70
Q

Why is passive transfer of maternal IgG to the fetus important?

A

Providing immunity to the newborn during its first few months of life, when its immune system is immature

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71
Q

Is IgG better at agglutination or precipitation? why?

A

Precipitation because it involves small soluble particles, which are brought together more easily by the relatively small IgG molecule.

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72
Q

What else is IgM called? Where does it get this name?

A

Macroglobulin because it is the largest of all the immunoglobulin classes

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73
Q

What is the sedimentation rate of IgM?

A

19S

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74
Q

What is the molecular weight of IgM?

A

900,000

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75
Q

What is the basic structure of IgM?

A

Pentameter of five monomers held together by J chain (joining)

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76
Q

Describe the J chain

A
  • Glycoprotein that holds together monomers
  • cysteine residues form disulfide bonds that link the carboxyl- terminal ends of adjacent monomers in IgM and IgA
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77
Q

What does each monomer of IgM contain?

A
  • Mu heavy chains and either kappa or lambda light chains
    -mu heavy chains possess one more constant domain (CH4) adding to its large size
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78
Q

What is the half life of IgM?

A

6 days

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79
Q

What percentage of immunoglobulins are IgM?

A

5-10%

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80
Q

What is the serum concentration range for IgM?

A

120-150 mg/dl

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81
Q

Why does IgM perform things more efficiently than IgG?

A

Because of IgMs multiple binding sites

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82
Q

What immunoglobulin is most efficient at triggering the classical pathway?

A

IgM because a single molecule can initiate the reaction when complement binds to two adjacent cha regions

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83
Q

Where are IgM mainly found?

A

In the intravascularpool and not in other body fluids or tissues because of its large size

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84
Q

What immunoglobulin is the first to appear after antigenic stimulation?

A

IgM

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85
Q

What is the first immunoglobulin that appears in maturing infants?

A

IgM

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86
Q

How many binding sites does IgM have?

A

10

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87
Q

What percentage of immunoglobulins are IgA?

A

10-15%

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88
Q

What is the normal serum concentration of IgA?

A

70-350 mg/dl

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89
Q

What is the molecular weight of IgA?

A

160,000

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90
Q

What is the sedimentation coefficient of IgA?

A

7S

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91
Q

Upon electrophoresis, IgA migrates where?

A

Between the beta and gamma bands

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92
Q

What immunoglobulins have complement fixation?

A

IgG
IgM

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93
Q

Describe the basic structure of IgA

A
  • Alpha heavy chains
  • contains one variable regions
  • contains three constant regions
  • dimer, two monomers held together by J chain
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94
Q

What are the two subclasses of IgA?

A

IgA1 and IgA2

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95
Q

How do IgA1 and IgA2 differ?

A

By 22 amino acids, 13 of which are located in hinge region (deleted in IgA2)

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96
Q

IgA2s lack of a hinge region causes what?

A

Make IgA2 more resistant to some bacterial proteinases that are able to cleave IgA1

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97
Q

Where are IgA2 found?

A

_ Secretions at mucosal surfaces
-along respiratory,urogenital, and intestinal mucosa
-appears in breast milks saliva, tears, sweat, and colostrum

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98
Q

Where are IgA1 found?

A

In serum

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99
Q

What is the major role of serum IgA?

A

-Anti-inflammatory agent
- downregulate IgG mediated phagocytosis, chemotaxis, bactericidal activity, and cytokine release

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100
Q

What is the J chain essential for in IgA?

A

Essential for polymerization and secretion of IgA

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101
Q

Where are Secretory IgA synthesized?

A

Plasma cells found mainly in mucosal-associated lymphoid tissue and is released in dimeric form

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102
Q

Describe secretary component

A
  • serves as specific receptors for IgA
  • precursor is present on surface of epithelial cells
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103
Q

What does secretary component derive from?

A

From epithelial cells found in plasma cells

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104
Q

Where do plasma cells secrete IgA?

A

Subepithelial tissue

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105
Q

What happens once IgA bind to SC precursors?

A

-Transcytosis
-Both of them are taken inside the cell and released at the opposite surface

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106
Q

What is the main function of secretory IgA?

A
  • To patrol mucosal surfaces and act as a first line of defense by preventing antigens from penetrating farther into the body
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107
Q

What is the important role of IgA?

A

Neutralizing toxins produced by microorganisms and helps prevent bacterial and viral adherence to mucosal surfaces

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108
Q

What immunoglobulin complex is trapped by mucus and coughed/sneezed out to protect the respiratory system?

A

IgA complex

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109
Q

Where is IgA found in humans?

A
  • breast milk
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110
Q

How does breastfeeding help to maintain the health of newborns?

A

Passively transferring antibodies

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111
Q

What cells possess specific receptors for IgA?

A

Macrophages
Monocytes
Neutrophil

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112
Q

What does binding to IgA specific receptor trigger?

A

A respiratory burst and degranulation, indicating that IgA is capable of acting as an opsonin

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113
Q

What percentage of total immunoglobulin are IgD?

A

0.001%

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114
Q

What is the half life of IgD?

A

1-3 days

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115
Q

What is the molecular weight of IgD?

A

180,000

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116
Q

What antibody migrates as fast as a gamma protein?

A

IgD

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117
Q

What is the molecular weight of the IgD delta chain?

A

62,000

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118
Q

Describe the hinge region of IgD

A

-unusually long
-58 amino acids

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119
Q

Why is IgD more susceptible to proteolysis than any other antibody?

A

Because of its long hinge region.this may be the reason for its short half life

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120
Q

Where are most IgD found?

A

Surface of unstimulated B cell

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121
Q

What is the second antibody that appears during an immune response?

A

IgD

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122
Q

What are the roles of IgD?

A
  • B cell maturation and differentiation
  • not exactly understood
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123
Q

Why is IgD an ideal early responder?

A

High level of surface expression and its intrinsic flexibility

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124
Q

What is IgE best known for?

A

Very low concentration in serum and the fact that it has the ability to activate mast cells and basophils

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125
Q

What percentage of total immunoglobulins are IgE?

A

0.0005%

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126
Q

What is the normal concentration of IgE in adults ?

A

0.005 mg/dl

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127
Q

What is the molecular weight of IgE?

A

190,000

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128
Q

What is the sedimentation coefficient for IgE?

A

8S

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129
Q

What percentage of IgE consists of carbohydrates?

A

12%

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130
Q

Describe the structure of IgE?

A

-epsilon heavy chain is composed of one variable and four constant domains
- A single disulfide bond joins each epsilon chain to a light chain, and two disulfide bonds link the heavy chains to one another

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131
Q

What is the most heat-liable antibodies? Why?

A

IgE heating to 56°C for between 30 minutes and 3 hours results in conformational change and loss of ability to bind to target cells

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132
Q

Does IgE participate in complement fixation, agglutination, or opsonization?

A

None of these

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133
Q

What cells does IgE bind to after synthesis? Describe?

A
  • Basophils
  • eosinophils
  • Langerhern cells
  • tissue mast cells
    → through nigh affinity receptors for the Fc portion of epsilon chain,which are exclusively on the surface of these cells
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134
Q

Where can plasma cells that produce IgE be located?

A

Primarily in lungs and in the skin

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135
Q

Where can mast cells be located?

A

Mainly in the skin,
-lining of the respiratory and alimentary tracts

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136
Q

What happens when two adjacent IgE molecules on a mast cell bind specific antigen?

A

A cascade of cellular events is initiated that results in degranulation of the mast cells with the release of vasoactive amines such as histamine and heparin

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137
Q

What does the release of IgE mediators induce?

A
  • Type I immediate hypersensitivity
  • “allergic reaction”
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138
Q

What are typical reactions with allergic reactions?

A
  • Anaphylactic shock
  • Asthma
  • diarrhea
    -hay fever
    -hives
    -vomiting
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139
Q

Describe IgE role

A

Serve a protective role by tinggering an acute inflammatory reaction that recruits neutrophils and eosinophils to the area to help destroy invading antigens that have penetrated IgA defenses

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140
Q

What occurs when the first time an individual is exposed to an antigen?

A

Primary antibody response

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141
Q

What are characteristics of primary antibody response?

A

-IgM shows up first
- Lag phase between the encounter with the antigen and the production of detectable antibody
- low affinity
- amount of antibody produced are relatively low and decline during the span of a few weeks

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142
Q

Describe the lag phase of primary antibody response

A
  • lasts 4 and 7 days
  • T and B cells are being activated to respond to the antigen by the T- dependent mechanism of antibody production
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143
Q

What does the lag phase of the primary antibody response result in?

A

Results in the generation of antibody- secreting plasma cells

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144
Q

What do the activated B cells from the primary response develop into?

A
  • Plasma cells
  • expand into clonesof memory cells (long lived)
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145
Q

What happen to memory cells when they are transformed from an activated B cells?

A

Memory cells have undergone genetic changes that allow them to:
① resist apoptosis
② express high affinity antigen receptors
③ switch their production from IgM to another isotope, predominantly IgG

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146
Q

Describe secondary antibody response?

A

It memory cells are exposed to the same antigen weeks, months, or even years later, they can rapidly differentiate into plasma cells and larger amounts of antibody are produced

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147
Q

What are characteristics of the secondary antibody production?

A
  • Shorter lag time → 1-2
  • high affinity
  • results in production of low levels of IgM that rapidly decline
  • results in higher levels of other immunoglobulin isotypes, mainly IgG -
    levels decline slowly and persistfor longer periods
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148
Q

Describe clonal selection hypothesis

A

-Body has numerous clones of lymphocytes, each possessing surface receptors with a unique specificity
-when body is exposed to antigen, the antigen selectively binds to receptors on cells to proliferate and mount antibody responses

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149
Q

What are individual lymphocytes genetically programmed to produced?

A
  • Immunoglobulin receptor with a single antigen specificity
  • occurs before contact of antigen, during B cell maturation
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150
Q

What are mature lymphocytes in lymphoid tissue prepared for?

A

To respond to a diverse array of potentially harmful antigens long before the body actually encounters them

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151
Q

Describe an human immunoglobulins physical features

A

-found in 3 unlinked clusters
-heavy chains are located on chromosome 14
-kappa light chain is found on chromosome 2
-lambda light chain is found on chromosome 22
-within each of clusters, a selection process occurs

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152
Q

When can a gene be transcribed and translated into functional antibody molecule?

A

Not until it undergoes rearrangement l, assisted by special recombinase enzymes

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153
Q

What does gene rearrangement involve?

A

Cutting and splicing process that removes much of the intervening DNA, resulting in a functional gene that codesfor a specific antibody

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154
Q

Where does rearrangement of the gene begin?

A

The heavy chains

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155
Q

What are the genes that code for vanable region of the heavy chain divided into?

A

Divided into 3 groups:
① V genes (variable) → 45 genes
② D genes (diversity) → 23 genes
③ J genes (joining) → 6

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156
Q

Where are all V, D and J genes present?

A

The germline DNA of a bone marrow stem cell

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157
Q

What are the set of genes that codes for the constant region?

A
  • in order: C”mu”, C”delta”, C”gamma”3, C”gamana”1, C”alpha”1, C”gamma”2, C”gamma”4, C”epsilon” and C”alpha”2
    -includes one gene for each heavy chain isotype
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158
Q

What occurs as the B cells mature and the heavy chain is constructed?

A

-a random choice is made from each of the sections so as to include one V gene, one D gene, one J gene, and one constant region

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159
Q

Joining of V gene, D gene, J gene and the constant region of a heavy chain is a two step process. What are the steps?

A

① in pro-B cells, one D gene and one J gene are randomly chosenand are joined by means of a recombines enzyme after the intervening DNA is deleted
②in pre-B cell stage, a V gene is joined to the DJ complex, resulting in a rearranged VDJ gene

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160
Q

Describe what the VDJ gene combination codes for.

A

-Codes for the entire variable region of a heavy chain.

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161
Q

What is allelic exclusion?

A

The genes on the second chromosome are not rearranged because the rearrangement of DNA on one chromosome 14 was successful the first time

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162
Q

What happens if the first rearrangement of heavy chains is unsuccessful?

A

-Rearrangement of the second set of genes on the other chromosome 14 occurs.
-this mechanism maintains clonal specificity by ensuring each B cell only expresses a single antigen receptor

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163
Q

What happens after rearrangement of the genes of the heavy chains?

A

-the variable and constant regions are joined
- occurs at the RNA level, thus conserving the DNA of the constant regions

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164
Q

During transcription and synthesis of messenger RNA of heavy chains, what occurs?

A

A constant region is spliced to the VDJ complex

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165
Q

Why is C“mu” the first to synthesized in heavy chains?

A

Closest to the J region

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166
Q

What are the markers of pre-B cells?

A

Mu heavy chains

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167
Q

What is transcribed after C”mu” region of the heavy chain?

A

-C”delta” region, which is closest to C”mu” region
- often transcribed along with C”mu”

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168
Q

What does the presence of both C”mu” and C”delta” regions of heavy chains allow?

A

Allows for mRNA for IgD and IgM to be transcribed at the same time.

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169
Q

When do light chain rearrangement occur?

A

After mu chains appear

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170
Q

What is a pivotal stepin light chain rearrangement?

A

Mu- chain synthesis (in heavy chain)

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171
Q

What is the main difference between heavy chain and light chain rearrangement?

A

Light chains lack a D region

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172
Q

What chromosome do the recombination of V and J segments in light chains occur?

A

Chromosome 2

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173
Q

What chromosome does coding for kappa chains (light) occur?

A

Chromosome 2

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174
Q

What does chromosome 22 code for

A

Lambda chain

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175
Q

What does the kappa locus contain?

A

Approximately:
-35 V(k) segments
-5 J(k) segments
-one functional C(k) region

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176
Q

Describe VJ joining of light chains?

A

-Accomplished by cutting out one intervening DNA
-results in the V(k) and J(k) segments becoming permanently joined to one another on the rearranged chromosome

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177
Q

Describe transcriptions route of a light chain

A
  • begins at one end of the V(k) segment and proceeds through the J(k) and C(k) segments
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178
Q

What happens when the J segments have not rearranged in a light chain?

A

Removed by RNA splicing, which occurs during translation

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179
Q

What happens when a successful rearrangement of the kappa genes occurs?

A

Keeps the other chromosomesfrom rearranging and shuts down any recombination of the lambda chain locus on chromosome 22

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180
Q

When does lambda chain synthesis occur in a light chain?

A

Only it a nonfunctioning gene product arises from kappa rearrangement

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181
Q

What does the lambda locus contain?

A

Approximately:
-30 V(lambda) segments
-4 J(lambda) segments
-4 C(lambda) segments

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182
Q

It functional heavy and light chains are not produced in a B cell, what happens?

A

Cell dies by apoptosis

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183
Q

Light chain are joined with mu chains to form what?

A

-A complete IgM antibody
-first appears in immature B cells

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184
Q

What happens once IgM and IgD present on the surface membrane?

A

The B cell is fully mature and capable of responding to antigen

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185
Q

What an essential for initiating the VDJ recombination during B cell maturation?

A

Recombinaseenzymes, RAG-1 and RAG-2

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186
Q

What is the role for RAG-1 and RAG-2?

A

-recognize specific recombination signal sequences in the DNA that flank all immunoglobulin gene segments

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187
Q

What is junctional diversity?

A
  • V, D, and J segments doesn’t always occurat a fixed position, so each sequence can vary by small number of nucleotides
    -major contributor to diversity in the variable-region genes
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188
Q

Where do immunoglobulins get their variation diversity from?

A

① Functional diversity
② different heavy chains can combine to different light chains
③ somatic hypermutation

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189
Q

What is somatic hypermutation?

A

-can occur after the B cell has had contact with antigen
-during Tcell-dependent antibody response,
Cytokines are produced that stimulate the B cellsto divide so that the response to the antigen is enhanced

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190
Q

What is affinity maturation?

A

-mutationin some of these B cells result in immunoglobulin receptors that can bind the antigen more strongly, and these B cells become the dominant clones as the immune response evolves

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191
Q

What is class switching?

A

As the immune response progresses, B cells may become capable of producing antibody of another class

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192
Q

What is switch recombination?

A

-a portion of the constant region DNA is deleted and the remaining C(h) genes are placed adjacent to the variable region genes
- allows the same VDJ region to be coupled with a different C region to produce antibody of a different class but having identical specificity for antigen

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193
Q

What determines where switching takes place and which C(H) gene will be transcribed?

A

Contact with T cells and cytokines

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194
Q

What does a normal response to an antigen result in?

A

Production of polyclonal antibodies because ever purified antigen has multiple epitopes that stimulate a variety of B cells

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195
Q

What are monoclonal antibodies?

A
  • Derived from single antibody-producing cell that has reproduced many times to form a clone
    -all the cells in the clone are identical and the antibody produced is exactly the same
    -directed against a specific epitope on an antigen
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196
Q

What is a hybridoma?

A

-Fusion of activated B cell and myeloma cell
-myeloma cell chosen lacks essential enzymes and cannot produce own antibodies

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197
Q

How does production of hybridomas begin?

A

By immunizing a mouse with the desired antigen

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198
Q

What is the traditional process of mouse monoclonal antibody production?

A

① immunize a mouse with a specific antigen
②harvest spleen cells from mouse spleen
③ combine spleen cells with myeloma cells in the presence of PEG
④select fused cells and screen for presence ot desired antibody
⑤ grow positive cells in larger quantities

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199
Q

Were initial monoclonal antibodies in vivo or in vitro?

A

In vitro

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200
Q

Describe what was used before the development of monoclonal antibodies?

A

Antibody reagent could only be produced my immunizing animals such as horses or goats with the desired antigen and isolating polyclonal antibodies from the animal serum

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201
Q

What are the primary advantages of the monoclonal antibody reagents?

A
  • They provide decreased lot-to-lot variation
  • increased specificity toward a single epitope, rather than multiple epitopes of an antigen
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202
Q

What has been used as therapeutic agents to treat a variety of diseases?

A

Monoclonal antibodies

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203
Q

What is a major limitation of using mouse monoclonal antibody as therapeutic agents

A
  • They are highly immunogenic for humans, inducing the development of human-anti-mouse antibodies (HAMAs) that can cause severe hypersensitivity reactions
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204
Q

Describe carbohydrates in any immunoglobulin?

A
  • Localized between the CH2 domains at the two H chains
  • increases the solubility of immunoglobulin
  • provides protection against degradation
    -enhances functional activity of the Fc domains
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205
Q

Where are isotypes located?

A

Constant region of heavy chains

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206
Q

Where are allotypes located?

A

In the constant regions of the IgG subclasses, one IgA subclass, and the light chain

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207
Q

Where are idiotypes located?

A

Amino terminal regions of heavy and light chains

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208
Q

Where do antigens bind on immunoglobulins?

A

Hypervariable regions that contain CDRs

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209
Q

What does complement fixation accomplish?

A

① enhances inflammatory response
②uses a positive feedback cycle to promote phagocytosis
③ enlists more defensive elements

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210
Q

Explain process of complement fixation

A

①antibodies bound to cells change shape and expose complement binding sites
②this triggers complement fixation and cell lysis

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211
Q

Describe neutralization of antibody action

A

Antibodies bind to and block specific sites on viruses or exotoxins, thus preventing these antigens from binding to receptors on tissue cells

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212
Q

Describe agglutination of antibody action

A
  • makes antigen- antibody complexes that are cross-linked, causing clumping
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213
Q

What is precipitation of antibody action?

A
  • Soluble molecules are cross-linked into large insoluble complexes
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214
Q

What enhances phagocytosis at the antigen- antibody complex?

A

-neutralization
-agglutination
- precipitation
- complement

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215
Q

What enhances inflammation of antigen-antibody complex?

A

Complement

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216
Q

What is the sedimentation coefficient of IgD?

A

7S

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217
Q

What are cytokines?

A

-Chemical messengers that regulate immunity
-small proteins that bind to and activate receptors located on target cells.

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218
Q

Describe regulations of cytokines?

A

-important in determining whether cytokine action will be effective or inappropriate
- massive overproduction and dysregulation of cytokines can lead to hypercytokinemia
- results in hypotension, fever,edema, multi- organ failure, or death

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219
Q

What is pleiotropy?

A

Single cytokine with many different actions

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220
Q

What is redundancy?

A

-Occurs when different cytokines activate some of the same pathway and genes
- can be explained by the fact many cytokines share receptor subunits

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221
Q

How is cytokine activity classified?

A

According to the distance traveled between the producing cell and its target cells

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222
Q

What is autocrine?

A

Cytokines that bind to receptors on the same cell from which they were secreted

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223
Q

What is paracrine?

A

Cytokines that act on cells within tissue region surrounding their cellular source

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224
Q

What is endocrine?

A

Some cytokines diffuse into the bloodstream, allowing them to influence cells far from the cells that produce them.

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225
Q

What is synergistic?

A

Interactions that complement and enhance each other

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226
Q

What is antagonism?

A

If one cytokine counteracts the action of another

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227
Q

What is a cytokine cascade?

A

Many cytokines induce the production of additional cytokines by target cells

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228
Q

What is the antagonist of IL-4?

A

TNF-alpha

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229
Q

What synergies with IFN- gamma?

A

TNF-alpha

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230
Q

What is hypercytokinemia?

A
  • Also referred to as cytokine storm
  • massive overproduction and dysregulation of cytokines can result in hyperstimulation of the immune response
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231
Q

What are major proinflammatory cytokines?

A

-TNF-alpha
-IL-1
-IL-6
-IFN-gamma

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232
Q

What are major anti-inflammatory cytokines?

A

-TGF-beta
-IL-10
-IL-13
-IL-35

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233
Q

What are the primary cytokines provoked by infection with extracellular microbes?

A

IL-1
IL-6
TNF-alpha

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234
Q

What happens once IL-1, IL-6, and TNF- alpha are produced?

A

mediate a handful of paracrine effects:
① increased capillary permeability
② increased platelet aggregation
② alterations of adhesion molecule expression on capillary endothelial cells

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235
Q

Describe increased capillary permeability that IL-1, IL-6, and TNF-alpha induces

A

-Allows soluble anti-microbial proteins to enter the tissues from blood plasma
-anti-microbial proteins → complement,and C-reactive protein

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236
Q

Describe increased platelet aggregation caused by IL-1, IL-6, and TNF-alpha

A

Helps to seal off local blood vessels presenting dissemination of the infection into the blood

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237
Q

Describe alteration of adhesion molecule expression on capillary endothelial cells caused by IL-1, IL-6, and TNF-alpha

A

Enhances entry of leukocytes from the blood into inflamed tissue

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238
Q

What effects occur when a severe infection stimulates production of larger quantities of inflammatory cytokines?

A

Causes systemic endocrine effects:
① an increase in body temperatures, which may make the body less hospitable to invading microbes
②an increase in the production of immune cells by the bone marrow and acute phase reactants by the liver
③ subject to feeling ill

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239
Q

What is the most important role of IL-1, IL-6, and TNF- alpha?

A

Recruiting effector cells, such as neutrophils and monocytes, into inflamed tissues.

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240
Q

How many cytokines are in the IL-1 family?

A

11

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241
Q

What are the best characterized cytokines of the IL-1 family?

A

IL-1alpha
IL-1beta
IL-1RA

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242
Q

Where are IL-1beta and IL-1RA expressed?

A

Dendritic cells
Macrophages
Monocytes

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243
Q

Where is IL-1alpha expressed?

A

-In innate phagocytic cells
-epithelial cells of skin, lungs, and GI tract

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244
Q

What can induce production of IL-1?

A

-Microbial components
- such as lipoteichoic acid, bacterial or viral nucleic acids, and other cytokines

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245
Q

Describe IL-1alpha

A
  • retained within the cell cytoplasm
  • only released after cell death
  • presence of IL-1alpha helps to attract inflammatory cells to areas where cells and tissues are being damaged or killed
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246
Q

What is IL-1beta released from?

A

Macrophages
Monocytes

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247
Q

Describe IL-1beta

A
  • mediates most paracrine (local) and hormonal (systemic) activity
  • before secretion, IL-1beta must be cleaved intracellularly to an active form
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248
Q

What is the most important paracrine effect of IL-1beta?

A

Recruiting immune cells into inflamed tissues

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249
Q

What happens when IL-1beta and IL-1 receptors bind on blood vessels of endothelial cells?

A

-Alter adhesion molecule expression and stimulates the production of chemokines
-changes cause immune cells (granulocytes and monocytes)to stop moving through the blood and begin diapedsis

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250
Q

Why is IL-1beta referred to as endogenous pyrogens?

A

Its ability to induce fever

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251
Q

What purposes does a fever have?

A

① inhibit growth of many bacteria and fungi
② ‘increase the microbicidial activities of macrophages and neutrophils
③ contribute to feeling of discomfort and fatigue, compelling individuals to rest

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252
Q

What are the overall roles of IL-1beta?

A

① activation of phagocytes
② induce fever
③ production of acute-phase reactant

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253
Q

Where does IL-1RA get its name?

A

It antagonizes or works against IL-1 cytokines

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254
Q

How does IL-1RA accomplish its antagonism of the IL-1 family?

A

By binding to only one of the two transmembrane proteins that compose the IL-1 receptor

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255
Q

What occurs when IL-1RA is lighted by IL-1alpha and IL-1beta?

A

Two receptor subunits are brought together, initiating an intracellular signaling cascade that alerts the target cell to presence of IL-1

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256
Q

What are TNF products of?

A

Macrophages
Lymphocytes

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257
Q

How many different proteins does the TNF family have?

A

19

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258
Q

Describe CD40 ligand

A

Essential for signaling between T and B cells

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259
Q

What is the most important TNF in inflammation?

A

TNF-alpha

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260
Q

What is a major inducer of TNF-alpha production?

A

Microbial substances such as LPS

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261
Q

What is LPS?

A

A component of the cell walls of gram-negative bacteria

262
Q

TNF-a is a ligand for what two receptors?

A

-TNFR1 →expressed on many tissues , and cells throughout body
-TNFR2→ expression limited to cells of
Hematopoïetic origin and endothelial cells

263
Q

Describe TNFbeta

A

-soluble
- produced by lymphocytes→ special class called lymphoid tissue inducer cells
- causes cell death (cytotoxicity)
-plays role in development of lymphoid tissues in the GI tract

264
Q

What are IL-6 related to?

A

-type I IFNs
- several hematopoietic growth factors

265
Q

What do two identical IL-6 polypeptide chains come together and form?

A

Homodimer (active form of cytokines)

266
Q

What are the most common sources of IL-6? Other sources?

A

Macrophages
Monocytes

Others:
Endothelial cells
Fibroblasts
lymphocytes
Skeletal muscle cells

267
Q

The activity of IL-6 is highly _______.

A

Pleiotropic

268
Q

What are the innate roles of IL-6?

A

-stimulates the production of acute-phase proteins by liver hepatocytes
- This increases the production and release of granulocytes by the bone marrow

269
Q

What are the adaptive roles of IL-6?

A

-increases activation of B and T cells
-modulates immunoglobulin synthesis by causing B cells to proliferate and differentiate into plasma cells

270
Q

What are the IL-6 receptor subunits?

A

IL-6R
gp130

271
Q

With IL-6 bound, what happens when IL-6R subunit assembles with gp130?

A
  • prompts conformational change in the gp130
  • allows its cytoplasmic domains to initiate intracellular signaling cascades, driving the expression of IL-6 mediated genes that code for products such as C-reactive protein, complement proteins, and fibrinogen
272
Q

What are chemoxines?

A

Subgroup of cytokines that influence the motility and migration of their target cells

273
Q

How are chemokines classified?

A

Into four families based on the sequence of amino acids found in their N- terminal,specifically the positioning of cysteine residues

274
Q

What are the four families of chemokines?

A

① CXC
② CC
③ C
④ CX3C

275
Q

Describe CXC chemokines

A

-contain single amino acid (X)between the first and second cysteines

276
Q

Describe CC chemokines

A

-the cysteines are found together, with no intervening amino acid

277
Q

Describe C chemokines

A

Has only a single cysteine

278
Q

Describe CX3C chemokines

A

Have 3 amino acids between the cysteines

279
Q

What is the most important effect of chemokines?

A

Recruitment of leukocytes from the blood into infected or damaged tissues

280
Q

How do chemokines accomplish recruitment of leukocytes?

A

By modulating the adhesion between leukocytes to roll along capillary walls and to subsequently exit the blood vessel and enter into the tissues

281
Q

What are interferons?

A

Soluble substances produced by virally infected cells that interfere with the ability or viruses to replicate by making host cells less hospitable to viral takeover

282
Q

What are the 3 groups of IFNs?

A

Type I
Type II
Type III

283
Q

What are the most important cytokines in response to viral infections?

A

IFN-alpha
IFN-beta
(Both type I)

284
Q

What is IFN- alpha produced by?

A

Dendritic cells
Macrophages

285
Q

What is IFN-beta produced by?

A

Wide variety of infected cells

286
Q

What are the functions of type I IFN?

A

① interfere with viral replication
② activate NK cells
③ enhances expression of class I MHC proteins on target cells

287
Q

What happens when type I IFN receptors are ligated by IFN-alpha and IFN-beta?

A

Cause NK cells to become activated, traffic to virally infected area and rapidly expandin number

288
Q

What is the most important innate defense mechanism against viral infection?

A

Combination of IFN-alpha and IFN-beta and NK cell killing

289
Q

What are the cytokines associated with adaptive immunity secreted by mostly?

A

T cells, especially T helper cells (CD4+)

290
Q

What are the 4 subpopulations of T helper cells

A

Th1
Th2
Th17
Treg cells

291
Q

What is differentiation ( related to Th cells)?

A

Th cells undertake a process during which they are transformed into one of the four subclasses

292
Q

What is Th cell differention influenced by?

A

Cytokines found in the lymph node during T-cell activation and early differentiation

293
Q

What causes differentiation to the Th1 lineage?

A

Dendritic cell production of cytokine IL-12

294
Q

What drives antibody mediated immunity

A

IL-4

295
Q

What arises in the presence of IL-23?

A

Th17 cells

296
Q

What are produced in response to TGF-beta?

A

Treg cells

297
Q

What is the hallmark of Th1 cells?

A

-high level expression of the proliferative cytokine IL-2 and IFN- gamma, a type II IFN

298
Q

What are the roles of Th1 cells?

A

① Expand to combat infection with viruses and intracellular bacteria
②promote cell-mediated immunity with cytotoxic T cells, and activate macrophages
③ ‘cause antigen-activated B cells to produce IgG1 and IgG3 antibodies capable of opsonization and fixing complement

299
Q

What is another name for IL-2?

A

T-cell growth factor

300
Q

What are the roles of IL-2?

A

①drives proliferation and differentiation of both T and B cells
② enhances the lytic activity of NK cells
③ causes naive Th to differentiate into Th1 cells

301
Q

In cooperation with IFN-gamma, what does IL-2 do to naive T helper cells?

A

Differentiate into Th1 cells

302
Q

What are IL-2 receptors (IL-2R) composed of?

A

3 protein subunits:
① alpha
② beta
③ gamma

303
Q

What is the primary cytokine of the Th1 response?

A

IFN-gamma

304
Q

What are the roles of IFN-gamma?

A

① influences expression of more than 200 target-cell genes
② stimulates antigen presentation by class I and class II MHC
③ potent activator of macrophages
④ involved in regulation and activation of CD4+ Th1 cells, CD8+ cytotoxic T cells and NK cells

305
Q

What are the most influential Th2 cytokines?

A

IL-4
IL-10

306
Q

What are IL-4 receptors expressed on?

A
  • Lymphocytes
  • nonhematopoietic cells
307
Q

What is the IL-4 activity on naive T cells?

A

-turns on genes that generate Th2 cells and turns off genes that promote Th1 cells

308
Q

What are Th2 cells responsible for regulating?

A
  • Allergies
    -autoimmune disease
    -parasites
309
Q

What does IL-4 induce production of

A

-MHC I
-IL-4
-IL-5
-IL-13
-CD80
-CD86
-IgG2a
-IgE

310
Q

What does IL-5 do along with IgE?

A

Drives differentiation and activation of eosinophils in both allergic immune response and responses to parasitic infection

311
Q

What does IL-13 and IL-4 have in common?

A

-induce worm expulsion
-favor IgE class switching

312
Q

How do IL-4 and IL-13 differ?

A

IL-13 plays anti-inflammatory role by inhibiting activation and cytokine secretion by monocytes

313
Q

What is IL-10 produced by?

A
  • Macrophages
  • monocytes
  • CD8+ cells T cells
  • CD4+ Th2 cells
314
Q

In one word, how would you describe the effects of IL-10?

A

Inhibitory

315
Q

What are the roles of IL-10?

A

① has anti-inflammatory and suppressive ‘ effects on Th1 calls
② inhibits antigen presentation by macrophages and dendritic cells
③ down regulates immune response by counteracting IFN-gamma

316
Q

What is the antagonist of IFN- gamma?

A

IL-10

317
Q

How can Treg cells be identified?

A

Expression of CD4, CD25, and FoxP3

318
Q

When do Treg cells form?

A

Either during thymic development or differentiate from naive T cells in the periphery

319
Q

What are Treg cells called when the form outside of the thymus?

A

Induced Tregs

320
Q

Why are Treg cells essential?

A

For establishing peripheral tolerance to a wide variety of self-antigens ant harmless antigens

321
Q

What are the roles of Treg cells?

A

① establish peripheral tolerance to self-antigens and harmless antigens
② produce suppressive cytolanes: TGF-beta and IL-10
③down regulate immune response to prevent chronic inflammation (main)
④may preventtumor cells from attack by inhibiting cancer-fight cells

322
Q

What are the hypotheses for how Treg cells suppress immunity?

A

① The production of suppressive cytokines, such as IL-10 and TGF-beta
② disruption of T-cell metabolism
③ direct cytotoxic killing of T cells and APCs
④ modulation of signaling between APC and T cells

323
Q

What does Th17 subset secrete?

A

IL-17 family of cytokines

324
Q

What are the cytokines that differentiate T cells to maintain them as Th17?

A

TGF-beta
IL-6

325
Q

What cytokine play a role in finalizing the commitment to Th17?

A

IL-23

326
Q

What is IL-23 produced by?

A

Dendritic cells
Macrophages

327
Q

What is the most studied IL-17 cytokine?

A

IL-17A

328
Q

What are the roles of Th17?

A

① host defense against bacterial and fungal infections at mucosal surfaces.
② secretion of IL-17
③promote recruitment of neutrophils
④ promote release of antimicrobial peptides
⑤ when dysregulated, may promote pathogenesis of several inflammatory diseases

329
Q

What does IL-17 induce the expression of? And where?

A

TNF-alpha
IL-1beta
IL-6
In epithelial cells, endothelial cells, keratinocytes, fibroblasts, and macrophages

330
Q

What cytokines induce epithelial cells, endothelial cells, and fibroblasts to produce CXC ligand 8 (CXCL-8)?

A

-IL-17A and IL-17F

331
Q

Why is CXCL-8 crucial?

A

For the recruitment of neutrophils to the site of inflammation

332
Q

What are the APC cytokines?

A

IL-12 and IL-23

333
Q

What are the primary mediators of hematopoiesis called? Why?

A

CSFs→ ‘
-IL-3
- erythropoietin (EPO)
-granulocyte colony stimulating factor (G-CSF)
-macrophage colony stimulator factor (M-CSF)
And granulocyte-macrophage colony-stimulating factor (GM-CSF)

334
Q

Why does IL-3 act on bone marrow stem cells?

A

To begin differentiation cycle

335
Q

What happens if M-CSF is activated?

A

The cells become macrophages

336
Q

What is the role of M-CSF?

A

Increases phagocytosis, chemotaxis, and additional cytokine production in monocytes and macrophages

337
Q

What happens if G-CSF is activated?

A

Cells become neutrophils

338
Q

What are the roles of G-CSF?

A

① Enhances function of mature neutrophils
② Affects the survival, proliferation, and differentiation of all cell types in neutrophil lineage
③ decreases IFN-gamma production
④ increases production IL-4 in T cells
⑤ mobilizes multipotent stem cells from the bone marrow

339
Q

What does GM-CSF do?

A

Acts to drive differentiation toward other WBC types

340
Q

What does EPO do?

A
  • Regulate RBC production in the bone marrow
341
Q

What is EPO primarily produced by?

A

The kidneys

342
Q

What is recombinant EPO?

A
  • Administered to improve RBC counts for individual with anemia and those with cancer
343
Q

What happens when EPO induce RBC proliferation?

A

Improves oxygenation of the tissues and eventually switches off EPO production

344
Q

What is the normal serum EPO values?

A

5-28 U/L

345
Q

What is anti-cytokine therapy?

A

Aims to break vicious cycle of chronic inflammation by targeting the interactions between specific cytokines and their cognate receptors

346
Q

Describe the first anti-cytokine therapeutics

A

Mostly murine monoclonal antibodies

347
Q

Describe newer anti-cytokine agents

A
  • Greatly improved using recombinant DNA techniques to generate humanized monoclonal DNA antibodies that are much less immunogenic
348
Q

Describe infliximab

A
  • Chimeric antibody containing human constant regions and murine variable regions that bind specifically to human TNF-alpha
    -treatment for Crohn’s disease, RA, ulcerative colitis
    -blocks TNF-alpha activity rapidly, dramatically reducing inflammation
349
Q

Describe the blockade of IL-17 function

A

-IL-17 blocking antibody to prevent IL-17 mediated pathogenesis
-another treatment

350
Q

Describe the hybrid protein based anti-cytokine therapy

A
  • Development of a class of hybrid proteins containing cytokine receptorbinding sites attached to immunoglobulin constant regions
    -Etanercept approved for use in humans
351
Q

Describe Etanercept

A
  • Consists of extracellular domains of type 2 TNF receptor fused to heavy chain of constant region of IgG1
    -fusion protein can bind TNF-alpha and block its activity
    -cost effective
    -reduces signs/symptom, disease activity, and disabilities
    -treatment for RA, any losing spondylitis, psoriasis, pediatric arthritis, and pediatric psoriasis
352
Q

What is the half life of Etanercept?

A

4.8- days

353
Q

Describe ixekizumab

A

-block to prevent IL-17 mediated pathogenesis
-treatment for plaque psoriasis, psoriasis and any losing spondylitis

354
Q

What are 3 cytokine assayformats?

A

① Multiplexed enzyme-linked immunosorbent assays(ELISAs)
② microbead assays
③ ELISpot assays

355
Q

Described Multiplexed ELISAs

A
  • Can detect many pro- and anti- inflammatory cytokines in one reaction
  • allow for simultaneous detection of several cytokines from serum or plasma in a single test run.
  • has “ spots “
356
Q

Describe microbead assays

A
  • Allow for the simultaneous detection of multiple cytokines in a single tube
    -each bead type has own fluorescent wavelength. When combined with fluorescent secondary antibody bound to a specific cytokine, allows for detection stop to 100 different analyses in one tube
357
Q

What biomarkers are simultaneously measured by multiplexed bead array?

A

-CRP
-Th1
-Th2
- proinflammatory cytokines
-IFN-gamma
-IL-2
-IL-4
-IL-5
-IL-10
-CSFs

358
Q

Describe ELISpot

A

-similar to ELISA performed on in vitro - activated peripheral WBC
- Allow the detection and enumeration of individual cytokine-secreting cells
- performed using cell culture microplates coated with cytokine-specific capture antibodies

359
Q

What is a clinical application that ELISpot is well-likedfor?

A

The detection of circulation Th1 cells that secrete IFN-gamma in responseto an antigen

360
Q

What is the ELISpot process?

A

① PBMCs are added to the wells of antibody- coated microplate and treat with synthetic protein antigen
② incubation period → Th1 cells secrete cytokines as they rest as the rest at the bottom of the microplate well.
③ PBMCs and any soluble substances (cytokines) are washed from wells
④ detection antibody specific to the target cytokine, is added to wells

361
Q

What is the role of ELISpot detection antibody?

A

To produce a signal indicating where target cytokine is bound to capture antibody

362
Q

What do the “spots” represent in ELISpot?

A

Tiny, elliptical silhouettes of captured IFN- gamma speckling plate bottom

363
Q

What is a drawback of having protein based technologies?

A

Short half life of certi an cytokines

364
Q

What is PCR product?

A

Made using fluorescent- labeled primer and can be hybridized to either solid or liquid phase arrays

365
Q

Describe the solid-phase array of PCR

A

-have up to 40,000 spots containing specific single-stranded DNA (ssDNA) oligonucleotides representing individual genes
- fluorescence of a spot indicates that gene was expressed in the celland that cell was producing the cytokine

366
Q

Describe liquid arrays of PCR

A
  • use same beads as microbead arrays but have oligonucleotides on surfaces instead of antibodies. Snow up to 100 different complementary DNAs to be identified
  • combination of bead fluorescence and fluorescence of labeled cDNA produces an emission spectrum that identifies the cytokine gene that was expressed in cell
367
Q

What are the 4 approaches to anti-cytokine therapy?

A

①disrupting interaction between cytokines and their cognate receptors
②using monoclonal antibodies that function as cytokines agonists
③ hybrid proteins containing cytokine receptor binding sites attacked to Ig constant regions to block cytokine activity
④blocking IL-17 function

368
Q

What are Th2 cells involved in?

A

Antibody-mediated responses

369
Q

What are Th1 induced by?

A

Dendritic cell production of IL-12

370
Q

What are Th2 induced by?

A

IL-4

371
Q

What are Th17 induced by?

A

IL-23

372
Q

What are Treg cells induced by?

A

TGF-beta

373
Q

What are the 3 isoforms of TGF-beta?

A

TGF-beta1
TGF-beta2
TGF-beta3

374
Q

What are the roles of TGF- beta?

A

①induces antiproliferative activity in many cell types
② regulates cell growth, differentiation, apoptosis, migration, and the inflammatory response
③helps down-regulate the inflammatory response when no longer needed
④ inhibits activation of macrophages and the growth of different somatic cell types
⑤functions as an anti-inflammatory factor for mature T calls
⑥ block production of IL-12 and inhibits induction of IFN-gamma
⑦inhibits proliferation of activated B cells

375
Q

What are the roles of chemokines?

A

① enhance motility and promote migration of many types of WBC toward source of the chemokines (chemotaxis)
②modulate adhesion of WBCs to endothelial cells lining The blood vessels, facilitating extravasation into the tissues

376
Q

Describe TNF-alpha

A

-LPS is a major trigger of TNF- alpha production
- secreted by activated monocytes and macrophages
- cause vasodilation and increased vasopermeability
-activates T cells by inducing expression of MHC class II molecules, vascular adhesion molecules and chemokines

377
Q

Describe IL-1RA

A
  • Produced by dendritic cells, macrophages, and monocytes
  • Has an anti-inflammatory effect
378
Q

What are the roles of cytokines in innate immune response?

A

① induce inflammation
② recruit effector cellsinto inflamed tissues
③produce synthesis effects including fever, malaise, increased hematopoietic, increased production of acute phase reactants

379
Q

What are the Cytokines in innate immune response?

A
  • IL-1
  • chemokines
    -TNF- alpha
    -TGF-beta
    -IL-6
    -IFN-alpha
    -IFN-beta
380
Q

Describe cytokine actions

A

-Have multiple
-widespread distribution of receptors on many cells types
- ability to alter expression of numerous genes
- may share properties and receptors
- may have overlapping effects
- can determine whether host will be able to mount an effective defense

381
Q

What are the roles of complement?l

A

① cause lysis of forgein cells
② acts as opsonins
③ increase vascular permeability
④recruit monocytes and neutrophils to the area of antigen concentration
⑤trigger secretion of immunoregulatory molecules that amplify the immune response

382
Q

What is complement?

A

A series of more than 50 soluble and cell-bound proteins that interact to enhance host defense mechanisms against foreign cells

383
Q

Where is the plasma complement synthesized?

A

Liver (NOT C1 complement or factor D)

384
Q

What produces C1 complement?

A

Intestinal epithelial cells

385
Q

Where is Factor D made?

A

Adipose tissue

386
Q

Besides the liver, what is a good additional source of early complement components (C1,C2,C3, and C4)?

A

WBC

387
Q

What are the three pathways of complement system activation?

A

① classical
② alternative
③ lectin

388
Q

What is the end product of complement system activation?

A

Lysis of invading cells

389
Q

Describe classical pathway

A

-Involves 9 proteins that are trigger primarily by antigen-antibody complexes
- major role in natural defense system

390
Q

What classes of immunoglobulins activate the classic pathway?

A

IgM, IgG1, IgG2, and IgG3

391
Q

What is required for the classical pathway to activate complement?

A

Two IgG molecules must attach to antigen within 30 to 40 nm of each other
OR
certain cells substances can bind directly such as: CRP, several viruses, mycoplasmas, some protozoa and certain gram-negative bacteria’s

392
Q

Describe recognition unit of the classical pathway?

A
  • Formation of C1
393
Q

Describe activation unit of classical pathway

A

-once C1is bound, C4, C2, and C3 are activated

394
Q

Describe membrane attacks complex (MAC)?

A
  • Comprises of C5 through C9
  • completes lysis of foreign particles
395
Q

What is the first complement component of the classical pathways

A

C1

396
Q

Describe C1 of the classical pathway

A
  • Molecular complex of 740 kDa
  • consist of 3 subunits: C1q, C1r, and C1s
  • subunits require calcium to maintain structure
397
Q

What does C1r and C1s generate during the classical pathways

A

Enzyme activity to begin cascade

398
Q

What is the molecular weight of C1q 7

A

410 kDa

399
Q

How many globular heads of C1q must be bound to Fc receptors for initiation of the classical pathway?

A

2-6

400
Q

What are C1r and C1s?

A

Serine protease proenzymes, or zygomens

401
Q

What happens once the classical pathway is activated?

A

C1r cleaves a thioester bond on C1s, which in turn, activates it.

402
Q

Describe activated C1r

A

-extremely specific because its only known substrate is C1s

403
Q

Describe activated C1s

A
  • Has limited specificity,with its only substrates being C4 and C2
404
Q

What does it mean when C1s is activated?

A

Recognition stage ends

405
Q

What marks the beginning of the activation unit of the classical pathway?

A

-begins when C1s cleaves C4

406
Q

What marks the end of the activation unit in the classical pathway?

A
  • The production of the enzyme C3 convertase
407
Q

What is the second most abundant complement protein?

A

C4

408
Q

What is the serum concentration of C4?

A

600 ug/ml

409
Q

What occurs when C1s cleaves C4?

A

-Releases a 77_amino acid fragment called C4a
-it opens a thioester- containing active site on remaining part, C4b

410
Q

What happens if C4b takes longer than a few seconds to bind to protein or carbohydrate:

A

-will react with water molecules to form iC4b, which is rapidly degraded

411
Q

What does C4b bind to in the classical pathway?

A

-Antigen in clusters that are within a 40-nm radius of C1
- represents first amplification step apin the cascade

412
Q

For every C1 molecule attached, approximately how many C4 molecules are split and attached

A

30

413
Q

What occurs when C2 is combined with C4b is presence in magnesium ions?

A

-C2 is cleaved by C1s to form the fragments, C2a and C2b

414
Q

What is the molecular weight of C2a?

A

70 kDa

415
Q

What is the molecular weight of C2b?

A

34 kDa

416
Q

What is the combination of C4b and C2a called?

A

C3 convertase

417
Q

How is C4bC2a complex stability.?

A

Not very stable

418
Q

What is the half life for the C4bC2a complex?

A

15 seconds-3 minutes

419
Q

What occurs if C3 does not bind quickly?

A

Cleaved into two fragments, C3a and C3b

420
Q

What is the central constituent of the complement system?

A

C3

421
Q

What is serum concentration of C3?

A

1-1.5 mg/ml

422
Q

What is the most significant step of complement system?

A

Cleavage of C3 to C3b

423
Q

What is the molecular weight of C3?

A

190 kDa

424
Q

Describe structure of C3

A

-Consists of two polypeptide chains, alpha and beta
-alpha chain highly reactive thioster group

425
Q

What has to occur for C3b to have the ability to bind to hydroxyl groups on car bohydrates and proteins?

A

C3a is removed by cleavage of single bond in alpha chain, exposing the thioster

426
Q

What is the half life of C3b?

A

60 micro seconds is not bound to antigen

427
Q

What occurs after cleavage of C3 in the classical pathway?

A

About 200 molecules are split for every molecule of C4bC2a

428
Q

C3b also serves as a powerful _________

A

Opsonin

429
Q

What has specific receptors for C3b? Explain

A

Macrophages, primed to phagocytize antigen that has bound to C3b

430
Q

Where does C3b bind in classical pathway? What does this create?

A

-Within 40 nm of the C4bC2a
- C4bC2aC36 is created. Also called C5 convertase

431
Q

Describe the structure of C5

A
  • Contains two polypeptide chains, alpha and beta. Which are linked by disulfide bonds to form a molecule
432
Q

What is the molecular weight of C5?

A

190 kDa

433
Q

What are the two fragments is C5 split into?

A

C5a and C5b

434
Q

Describe C5a

A
  • 74 amino acid fragment
  • released into circulation
435
Q

Describe C5b

A

-attaches to cell membrane
- forms beginning of MAC
-extremely liable
-rapidly inactivated unless binding to C6 occurs

436
Q

Describe C5b-9

A
  • The MAC
    -these proteins do not have enzymatic activity
    -all present in much smaller amounts than preceding components
437
Q

Describe C8

A
  • made up of three dissimilar chains, alpha, beta, and gamma, joined by disulfide bonds
438
Q

Describe C9

A
  • Single polypeptide chain
  • carboxyl terminal end is hydrophobic
    -amino terminal end is hydrophilic
  • presence greatly accelerate lysis
439
Q

What is the hydrophobic parts role of C9?

A
  • Serves to anchor the MAC within the target membrane
440
Q

What occurs when sC5b-9 is formed in the classical pathway?

A
  • MAC produces a pole of 70 to 100A that allows ions pass in and out of the membrane
441
Q

How does destruction of target cells occur?

A

Occurs through an influx of water and a corresponding loss of electrolytes

442
Q

What is the molecular weight of C1q?

A

410 kDa

443
Q

What is the serum concentration of C1q?

A

150 ug/ml

444
Q

What diseases are associated with abnormal C1q, C1r and C1s?

A

SLE, recurrent infections

445
Q

What is the function of C1q?

A

Binds to Fc region of IgM and IgG, synaptic pruning

446
Q

What is the molecular weight of C1r?

A

85 kDa

447
Q

What is the serum concentration of C1r?

A

50 ug/ml

448
Q

What is the function of C1r?

A

Activates C1s

449
Q

What is the molecular weight of C1s?

A

85 kDa

450
Q

What is the serum concentration of C1s?

A

50 ug/ml

451
Q

What is the function of C1s?

A

Cleaves C4 and C2

452
Q

What is the molecular weight of C4?

A

205 kDa

453
Q

What is the serum concentration of C4?

A

300-600 ug/ml

454
Q

What is the function of C4?

A

Part of C3 convertase (C4b)

455
Q

What is the molecular weight of C2?

A

102 kDa

456
Q

What is the serum concentration of C2?

A

25 ug/ml

457
Q

What is the function of C2?

A

-binds to C4b → forming C3 convertase

458
Q

What diseases are associated with abnormal serum concentration of C4?

A
  • RA
  • SLE
    -infection
  • usually asymptomatic
459
Q

What diseases are associated with abnormal serum concentration of C2?

A

-SLE
-recurrent infection
- arthersclerosis
-may be asymptomatic

460
Q

What is the molecular weight of MBL?

A

200-600 kDa

461
Q

What is the serum concentration of MBL?

A

0.0002-10 ug/ml

462
Q

What is the function of MBL?

A

Binds to mannose

463
Q

What diseases are associated with abnormal serum concentration MBL?

A

-pneumococcal diseases
- sepsis
-Neisseria infections
-bacterial infection
-some autoimmunity
- mostly asymptomatic

464
Q

What is the molecular weight of MASP-1?

A

93 kDa

465
Q

What is the scrum concentration of MASP-1?

A

1.5-12 ug/ml

466
Q

What is the function of MASP-1?

A

Unknown

467
Q

What diseases are associated with abnormal serum concentration of MAPS-1?

A

3MC syndrome

468
Q

What is the molecular weight of MASP-2?

A

76 kDa

469
Q

What is the serum concentration of MASP-2?

A

Unknown

470
Q

What is the function of MASP-2?

A

Cleaves C4 and C2

471
Q

What diseases are associated with abnormal serum concentration of MASP-2?

A

-respiratory infections (pneumococcal diseases)
-mostly asymptomatic

472
Q

What is the molecular weight of factor B?

A

93 kDa

473
Q

What is the serum concentration of factor B?

A

200 ug/ml

474
Q

What is the function of factor B?

A

Binds to C3bto form C3 contentase

475
Q

What diseases are associated with abnormal serum concentration of factor B?

A
  • Neisseria
    -pneumococcal infections
476
Q

What is the molecular weight of Factor D?

A

24 kDa

477
Q

What is the serum concentration of factor D?

A

2 ug/ml

478
Q

What is the function of factor D?

A

Cleaves factor B

479
Q

What are diseases associated with abnormal serum concentration of factor D?

A

Bacterial infections

480
Q

What is the molecular weight of properdin?

A

55 kDa

481
Q

What is the serum concentration of properdin?

A

15 -25 ug/ml

482
Q

What is the function of properdin?

A

Stabilizes C3Bb-C3 convertase

483
Q

What disease are associated with abnormal serum concentrations of properdin?

A
  • Neisseria infections
  • Severe recurrent infection
484
Q

What is the serum concentration of C3?

A

1200 ug/ml

485
Q

What is the function of C3?

A

Key intermediate in all pathways

486
Q

What arc diseases associated with abnormal serum concentration of C3?

A
  • Glomerulonephritis
  • severe recurrent infection; aHUS, C3G, AMD with gain of function
487
Q

What is the semi concentration of C5?

A

80 ug/ml

488
Q

What is the function of C5?

A

Initiates MAC

489
Q

What diseases are associated with abnormal serum concentration of C5, C6, C7, and C8?

A

-Neisseria infection

490
Q

What is the molecular weight of C6?

A

110 kDa

491
Q

What is the serum concentration of C6?

A

45 kDa

492
Q

What is the function of C6?

A

Binds to C5b in MAC

493
Q

What is the molecular weight of C7?

A

100 kDa

494
Q

What is the serum concentration of C7?

A

90 ug/ml

495
Q

What is the function of C7?

A

Binds to C5bC6 in MAC

496
Q

What is the molecular weight of C8?

A

150 kDa

497
Q

What is the serum concentration of C8?

A

55 ug/ml

498
Q

What is the function of C8?

A

Starts pore formation on membrane

499
Q

What is the molecular weight of C9?

A

70 kDa

500
Q

What is the serum concentration of C9?

A

60 ug/ml

501
Q

What is the function of C9?

A

Polymerizes to cause cell lysis

502
Q

What are the diseases associated with abnormal serum concentrate of C9?

A

No known diseases

503
Q

What are the steps of the classical pathway?

A

Recognition unit
①The zygomens C1r and C1s are converted into active enzymes as binding of C1q occurs
② autoactivation of C1r results from a change that takes place as C1q is bound
③when activated, C1r cleaves a thioster bond on C1s, which activates it.
Activation unit
④ C1s cleaves C4 to create C4b and C2 to make C2a
⑤ C3 convertase (C4b2a) is formed
⑥ C3b binds to C4b2a to form C5 convertase (C4b2a3b)
MAC
⑦ C5 convertase splits C5 into C5a and C5b
⑧ C5b attaches to the cell membrane to initiate formation of the MAC (C5b6789)

504
Q

How is the lectin pathway activated?

A

By direct recognition of surface moieties that are found on pathogens

505
Q

How does the lectin pathway provides an additional link to the innate and adaptive immune response?

A

Because it involves nonspecific recognition of carbohydrates that are common continents of microbial cell walls

506
Q

How does the lectin pathway play an important role in infancy?

A

Defense mechanism during the interval between the loss of maternal antibody and the acquisition of a full-fledged antibody response to pathogens

507
Q

What are the 3 recognition molecules of the lectin pathway?

A
  • Lectin
  • ficolins
  • collectins ( CL-L1)
508
Q

Describe structures of lectin, ficolins, and collectins

A
  • All similar to C1q structure
509
Q

What is the key protein of the lectin pathway? Describe this protein

A

-Mannan binding lectin (MBL)
-binds to mannose or other related sugars in a calcium-dependent manner to initiate this pathway
-considered acute phase protein because produced in liver and normally present in serum

510
Q

What are the steps of the lectin pathway?

A

① binds to mannose or relaletal sugar to initiate pathway
② complex associates with MASP-1, MASP-2, and MASP-3. Complex act like C1qrs
③ MASP-2 cleaves C4 and C2
④ C3 convertase (C4b2a) is formed
⑤ C3b binds to C4b2a to form C5 convertase (C4b2a3b)
MAC
⑥ C5 convertase splits C5 into C5a and C5b
⑦ C5b attaches to the cell membrane to initiate formation of the MAC (C5b6789)

511
Q

What are the steps of the alternative pathway?

A

① C3 is hydrolyzedby water to produce C3b which binds Factor B, and together they attach to target tell surface
② B is cleaved by Factor D into the fragments Ba and Bb. Bb combines with C35 to form C3bBb, an enzyme with C3 convertase activity
③more C3is cleared, forming more C3bBb. This enzyme is stabilized by properdin and, it continues to cleave additional C3
④it a molecule of C3 remains attached to the C3bBbP enzyme, the convertase now has the capability to cleave C5. The C5 convertase this consists of C3bBbP3b.
⑤ C5b attaches to the cell membrane to initiate formation of the MAC (C5b6789

512
Q

What is the role of the alternative pathway?

A

Functions largely as an amplification loop for activation started for activation started from the classical or lectin pathways

513
Q

What are some triggering substances for the alternative pathway?

A
  • bacterial cell walls
  • some parasites
  • fungal cell wall
    -viruses/viral infected cells
    -tumor cell line
  • yeasts
    *these all serve as binding sites complex C3bBb
514
Q

What proteins are involved in the alternative pathway?

A
  • C3
  • C5-C9
  • factor B
  • factor D
  • P(properdin)
515
Q

Describe alternative pathway

A
  • Acts as a natural defense system
516
Q

What protein is not stable in plasma in the alternative pathway?

A

C3

517
Q

What is it called when C3 activates spontaneously?

A

-Tick-over
- results in iC3

518
Q

What has the ability to bind to factor B?

A

iC3 (C3b)

519
Q

What happens when C3b binds to factor B in the alternative pathway?

A
  • Factor D with magnesium can cleave B into Ba and Bb
520
Q

Describe factor D

A

-plasma protein that circulates in active enzyme form
- serine protease
-only substrate is bound to factor B

521
Q

What happens once B is cleaved into Ba and Bb in the alternative pathway?

A

① Ba goes off into plasma
② Bb binds to the surface of the triggering cellular antigen
③ if it does not bind quickly-it disintegrates

522
Q

Describe C3bBb stability

A

-Extremely unstable unless properdin binds to the complex
- properdin increases C3bBb complex half life from seconds to 30 minutes

523
Q

What is the role of of the majority of control proteins?

A

Aim to halting accumulation of C3b

524
Q

What does C1 inhibitor (C1-INH) inhibit?

A

-Activation of the first stages of the classical and lectin pathway

525
Q

What are the role of C1-INH?

A

① Inactivate C1 by binding to the active sites of C1r and C1s
② inactivates MASP-2 binding to MBL-MASP-2

526
Q

Where is C1-INH synthesized?

A

-Liver
- monocytes contribute

527
Q

Why is C1-INH considered a suicide inhibitor?

A
  • Can only inhibit one serine protease
528
Q

What are the four main regulators that inhibit C3 convertase further forming?

A
  • C4- binding protein (C4BP)
  • complement receptor type 1 (CR1)
  • membrane cofactor protein (MCP)
    -decay-accelerating factor (DAF)
    -ALL WORK IN CONCERT WITH FACTOR I
529
Q

What is MCP also known as?

A

CD46

530
Q

What is DAF is also known as?

A

CD55

531
Q

What is Factor I?

A
  • Serine protease that inactivates C3b and C4b when bound to one of these regulators
532
Q

Describe C4BP

A
  • Abundant in plasma
  • capable combining with fluid-phase or cell-bound C4b
  • blocks C4b from binding to C2
    -direct degradation by Factor I
533
Q

What is CR1 also known as

A

CD35

534
Q

Describe CR1

A

-Large polymorphic glycoprotein found on the cell surface of peripheral blood cells
- binds C3b and C4b, greatest affinity for C3b
- key receptor on platelets and RBC

535
Q

What type of peripheral blood cells have CR1s on their surface?

A
  • B cells
  • eosinophils
  • erythrocytes
  • follicular dendritic cells
  • macrophages
  • monocytes
  • neutrophils
  • T cells
536
Q

What is immune adherence?

A

The ability of cells to bind complement-coated particles

537
Q

What is the molecular weight of MCP?

A

50-70 kDa

538
Q

Where are MCPs found?

A
  • Found on the cell membrane of virtually all epithelial and endothelial cells except erythrocytes
539
Q

What is the most efficient cofactor for factor I?

A

MCP

540
Q

What serves as a cofactor for cleavage of C4b?

A

MCP, but not as efficient as C4BP

541
Q

Describe DAF

A
  • A membrane glycoprotein that has wide tissue distribution.
  • found on peripheral blood calls, endothelial calls, fibroblasts, and numerous types of epithelial cells
542
Q

What are the roles of DAF?

A

① capable of dissociating the C3 convertase of classical and lectin pathways
② it can bind to both C3b and C4b in a manner similar to CR1
③ can rapidly dissociate both from their binding sites, thus preventing the assembly of active C3 convertase

543
Q

Describe DAFs mobility

A
  • Covalently attached to a glycophospholipid anchor that is inserted into the outer layer of the membrane lipid bilayer
  • allows mobility within the membrane so that it can reach C3 convertase sites that are not immediately adjacent to it
544
Q

What does the presence of DAF on host cells protect them from what?

A

Bystander lysis

545
Q

What is bystander lysis?

A

-main mechanism used in discrimination of self from nonself because foreign cells do not possess this substance

546
Q

What are the steps of the alternative pathway REGULATION?

A

① factor H competes with factor B for binding to spontaneously (hydrolytically) activated C3b
② factor H dissociates any C3bBb complexes that form on self-cell surfaces
③ factor H is a cofactor with factor I (FI), enabling cleavage of C3b.The resulting iC3b loses enzymatic activity but is still an opsonin
④ CR1 is a cofactor with FI, enabling cleavage of iC3b. The resulting C3dg is an opsonin and a cofactor in B cell stimulation

547
Q

What is the principle soluble regulator of alternative pathway?

A

Factor H

548
Q

What does Factor H do in the alternative pathway?

A
  • Acts by binding to C3b to prevent binding of Factor B
549
Q

What is S protein?

A
  • Soluble control protein that acts a at deeper level of complement activation
  • also known as vitronectin
    -interacts with C5b-7 complex as it forms in fluid phasebut preventsit from binding to cell membranes
  • terminal pathway
550
Q

Describe membrane inhibitor of reactive lysis (MIRL)

A

-also known as CD59
- acts to block for motion of MAC
-widely distributed on the cell membranes of all circulating blood cells including RBC, on endothelial, epithelial, and on other types of cells

551
Q

What is the serum concentration of C1-INH?

A

240 mg/ml

552
Q

What is the main function of C1-INH?

A

Dissociates C1s and C1r from C1q

553
Q

What diseases are associated with abnormal serum concentration of C1-INH?

A

Hereditary angioedema

554
Q

What is the serum concentration of Factor I?

A

35 mg/ml

555
Q

What is the main function of Factor I?

A

Cleaves C3b and C4b

556
Q

What is the molecular weight of C1-INH?

A

105 kDa

557
Q

What pathways does C1-INH participate in?

A

Classical
Lectin

558
Q

What pathways does factor I participate in?

A

Classical
Lectin

559
Q

What diseases are associated with abnormal serum concentration of factor I and factor H?

A
  • recurrent pyogenic infections
  • aHUS or C3G
  • AMD with gain of function
560
Q

What is the molecular weight of Factor I?

A

88 kDa

561
Q

What is the molecular weight of factor H?

A

150 kDa

562
Q

What is the serum concentration of factor H?

A

300-450 kDa

563
Q

What are the main functions of factor H?

A

① cofactor with factor I to inactivate C3b
② prevents binding of B to C3b

564
Q

What pathways does factor H participate in?

A

Alternative

565
Q

What is the molecular weight of C4BP?

A

520 kDa

566
Q

What is the serum concentration of C4BP?

A

250 mg/ml

567
Q

What is the main function of C4BP?

A

Acts as a factor with factor I to inactivate C4b

568
Q

What pathways does C4BP participate in?

A

Classical
Lectin

569
Q

What diseases are associated with abnormal serum concentration C4BP?

A
  • Atypical morbus
    -Behcet’s disease
    -Angioedema
  • protein S deficit
570
Q

What is the molecular weight of S protein?

A

84 kDa

571
Q

What is the serum concentration of S protein?

A

500 mg/ml

572
Q

What is the main function of S protein?

A

-prevents attachment of C5b67 complex to cell membranes

573
Q

What pathways does S proteins participate in?

A

Classical
Lectin
Alternative

574
Q

What ligands are associated with DAF

A

C3b
C4b

575
Q

Where are DAF found?

A
  • B cells
  • endothelial cells
  • epithelial cells
  • fibroblasts
  • monocytes
  • neutrophils
  • platelet
  • RBCs
576
Q

What is the main functi{on of DAF?

A

-dissociates C2b or Bb from binding sites, thus preventing formation of C3 convertase

577
Q

What diseases are associated with DAF?

A

PNH (paroxysmal nocturnal hemoglobinaria)
protein-losing enteropathy

578
Q

What ligands are associated with MIRL?

A

C8

579
Q

What cells have MIRLs?

A
  • endothelial cells
  • epithelial cells
  • monocytes
  • neutrophils
  • platelets
  • RBC
580
Q

What is the main function of MIRL?

A

Prevent insertion of C9 into cell membrane

581
Q

What ligands are associated with MCP?

A

C3b
C4b

582
Q

What cells are MCPs found?

A
  • B cells
  • endothelial cells
  • macrophages
  • monocytes
  • neutrophils
  • platelets
  • T cells
583
Q

What is the main function of MCP?

A

Cofactor for factor I cleavage of C3b and C4b

584
Q

What is CR1 also known as?

A

CD35

585
Q

What ligands ave associated with CR1?

A

C3b
iC3b
C4b

586
Q

What is the main function of CR1?

A

Cofactor for factor I; mediates transport of immune complexes

587
Q

What is CR2 also known as?

A

CD21

588
Q

What ligands are associated with CR2?

A

C3dg
C3d
iC3b

589
Q

What is the main function of CR2?

A

-B cell co-receptor for antigen with CD19

590
Q

What cells are CR2 found?

A
  • B cells
  • epithelial cells
    -follicular dendritic cells
591
Q

What is CR3 also known as?

A

CD11b
OR
CD18

592
Q

What ligands are associated with CR3?

A

iC3b
C3d
C3b

593
Q

What cells are CR3 found?

A
  • macrophages
  • monocytes
  • neutrophils
  • NK cells
594
Q

What is the main function of C3?

A

Adhesion and increased activity of phagocytic cells

595
Q

What is CR4 also known as?

A

CD11c
CD18

596
Q

What ligands are associated with CR4?

A

iC3b
C3b

597
Q

What cells are CR4 found on?

A
  • Activated B and T cells
  • dendritic cells
  • macrophages
  • monocytes
  • neutrophil
  • NK cells
598
Q

What is the main function of CR4?

A

Adhesion and increased activity of phagocytic cells

599
Q

What diseases are associated with abnormal serum concentration of MIRL?

A

Paroxysmal nocturnal hemoglobinuria

600
Q

What are 4 biological manifestations of complement?

A
  • Amplifies inflammatory response
  • role in uptake and presentation of antigens in adaptive immune response
  • facilitates B cell activation
  • role in neural development
601
Q

What is present when the inflammatory response is amplified by complement?

A

① anaphylatoxins (C5a, C3a) →increases vascular permeability
② chemotâxins (C5a) → attract phagocytic cells to enhance phagocytosis
③ opsonins (C3b, C4b, iC3b, C3dg)→ coat damaged or foreign cells to enhance phagocytosis

602
Q

How can complement be harmful?

A

① it is activated systemically on a large scale, as in gram-negative septicemia
②it is activated by tissue necrosis and results in obstruction of the blood supply, as in myocardial infarction
③ lysis of RBCs occurs as in cold agglutinin disease or autoimmune hemolytic anemia

603
Q

Describe Atypical Hemolytic Uremia Syndrome

A

-rare kidney disorder that result in acute renal failure in children
-caused by mutations in genes coding for Factor H, MCP, Factor I, Factor B, C3 or thrombomodulin; or to autoantibodies against Factor H

604
Q

Describe C3 glomerulopathy

A

Inflammation of the renal glomeruli that maybe due to autoantibodies that cause C’ dysregulation (C3 nephrotic factors; C3NeFs)

605
Q

What do the techniques involve when trying to detect complement abnormalties?

A

-measurement of components as antigens in serum
-measurement of functional activity of complement pathways

606
Q

When detecting complement abnormalities, what are the immunologic assays of individual components?

A

-automated nephelometry or immunoturbidimetry
- radial immunodiffusion (RID)

607
Q

What are classical pathway assays?

A

① hemolytic titration (CH50) assay
② CH50 test for lysis of liposomes
③ ELISA to detect C9 epitopes exposed after binding
In MAC

608
Q

What are the alternative pathway assays?

A

①AH50
② ELISA to detect C3bBbP or C3bP

609
Q

What is the CH50 Test procedure?

A

① Serum to be tested is diluted serially and added to sensitized sheep RBC.
②tubes are incubated at 37°C
③ centrifuged to pellet the unlysed cells

610
Q

What is CH50 defined as?

A

As the reciprocal of the dilution that causes lysis of 50% of the cells used in the assay

611
Q

Describe the complement fixation test

A
  • Destroy any complement present in patient serum by heating serum to 56°C for 30 minutes
    -dilutions of serum are combined with known antigen and a measurement amount of Guinea pig complement
    -if patient antibody is present it will bind with the reagent antigen and complement be bound
612
Q

What are the steps of complement fixation test?

A

① add sheep RBCs that are coated with a hemolysin (will lyse if any complement is present)
② incubate and centrifuge tubes
③ read for hemolysis
④ it hemolysis is present→ No patient antibody→ test is negative. If hemolysis is absent→ patient antibody to complement→ test is positive

613
Q

What are some limitations(?) of complement fixation test?

A

① results are expressed as highest dilution showing no hemolysis
② controls must be used
③ more sensitive than agglutination and precipitation, less sensitive than labeled immunoassay
④ errors

614
Q

What errors could occur with the complement fixation test?

A

① amount of manual manipulations required makes it easy to make technical errors
② lack of standardization
③numerous controls discourage use in clinical laboratories

615
Q

What pathways are affected by abnormal C1q, C1r, and? C1s

A

Classical → low

616
Q

What pathways are affected by abnormal C4 and C2?

A

Classical → low
Lectin → low

617
Q

What pathways are affected by abnormal MBL and MASP2?

A

Lectin→ low

618
Q

What pathways are affected by abnormal B, D and P?

A

Alternative →low

619
Q

What pathways are affected by abnormal C3, and C5-C9?

A

All three→ low

620
Q

What pathways are affected by abnormal C1-INH?

A

Classical → low
Lectin → low

621
Q

What pathways are affected by abnormal Factors H and I?

A

All three → low

622
Q

What is recombinant C1-INH used to treat?

A

HAE

623
Q

What are some complement therapeutics?

A

①target key points in the complement pathways to treat disease
② recombinant C1-INH is used to treat HAE
③ monoclonal antibodY to C5 (eculizumab) is used to block formation of C5a and the MAC

624
Q

What is monoclonal antibody to C5 (eculizumab) used to treat?

A

-aHUS and PNH

625
Q

What decreases with monoclonal antibody to C5 ?

A
  • Soluble C5b-9 levels
  • CH50
  • AH50
626
Q

What are the symptoms of C3 glomerulopathy?

A
  • Cause inflammation of the glomeruli of the kidneys
  • hematuria
  • proteinuria
  • hypertension
  • gradual decline of kidney function
627
Q

What are symptoms of HUS?

A
  • Hemolytic anemia
  • low platelet count
  • acute renal failure
628
Q

What is the primary cause of HUS ?

A
  • Exposure to a Shiga toxin from acute diarherral illness
629
Q

What are levels of C3 and C4 routinely measured by?

A
  • Automated nephlometry or immunoturbidimetry.
630
Q

Describe nephlometry?

A

Measures the concentration of an individual complement protein according to the amount of light scattered by the antigen-antibody mixture

631
Q

Describe immunoturbidimetry

A

Based on reduction in light transmission resulting from immune complex formation

632
Q

What is the difference between the CH50 and AH50 assays?

A
  • Magnesium chloride is added to buffer
    -ethylene glycol tetraacetic acid added to buffer
  • calcium left out
633
Q

Describe the AH50 assay

A
  • Buffer chelates calcium, blocking classical pathway activation
    -rabbit RBC are used as the indicator
634
Q

Describe ELISA testing in alternative pathway

A
  • Can detect C3bBb or C3bP complexes in very small quantities
    -micrometer wells typically coated with bacterial lipopolyssachardes to trigger activation of the alternative pathways
635
Q

What are the assays that test for complement activation?

A
  • ELISA or multiplex versions of immunoassays
636
Q

What are the potential benefits of measuring complement fragments?

A

①more sensitive to any complement activation
② measuring anaphylatoxin levels directly can be informative about the degree of inflammation that is being driven by complement
③ by measuring individual fragments,it is possible to determine which pathways are activated and where any control is achieved in the cascade of complement activation

637
Q

This cells affect the innate immune response by inducing production of which cytolones?

A

IL-2
IL-4

638
Q

Describe macrophage- colony stimulating factor (M-CSF)

A

-if activated, the cells become macrophages
-increase phagocytosis, chomotaxis and additional production in monocytes and macrophages

639
Q

What is autocrine stimulation?

A

Affecting same cell that secreted it

640
Q

Describe colony stimulating factor

A

Stimulates formation of colonies of calls in the bone marrow

641
Q

What is an integrin?

A

Cell adhesion molecules on leukocytes

642
Q

Describe erythropoietin (EPO)

A

CSF that regulates RBC production in bone marrow

643
Q

Describe granulocyte colony stimulating factor (G-CSF)

A

-If activated, the cells become neutrophils,
-enhances function of mature neutrophils and affects survival, proliferation, and differentiation of all cell types in the neutrophil lineage

644
Q

Describe endocrine activity

A

Systemic affects

645
Q

Describe adaptive T regulatory 1 cells

A

-CD4+ T cells that are induced from antigen activated naïve T cells in presence of IL-10

646
Q

Describe granulocyte-macrophage colony stimulating factor(GM-CSF)

A

-cytokines produced by T cells and other cell lines that stimulates an increased supply of granuloytic cells and macrophages

647
Q

What is the main difference between IgE and IgG?

A

IgE has one more constant region

648
Q

What is the cytokine that promotes differentiation of T cell to The Th1 subclass?

A

IL-12

649
Q

What reasons are CSF given to cancer patients?

A

The increase production of certain types of leukocytes

650
Q

What is the best assay to measure a specific cytokine?

A

ELISA assay

MLT immunology (7 decks)

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