Immunology Exam 1 Flashcards

1
Q

Contrast innate and acquired immunity (4).

A
  • nonspecific VS specific
  • common to all living things VS vertebrates
  • present at birth VS developed over time
  • no memory VS memory
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2
Q

Examples of innate system elements (5).

A
  • Physiological barriers
  • PMLs
  • Macrophages
  • NK cells
  • Inflammation
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3
Q

endocytosis

A

ingestion of foreign macromolecules by pinocytosis or receptor-mediated endocytosis.

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4
Q

phagocytosis

A

ingestion and destruction of foreign particles.

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5
Q

opsonin

A

facilitator of phagocytosis. May be an antibody (ex IgG) or complement.

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6
Q

reticuloendothelial system

A

includes macrophages, dendritic cells (spleen and lymph nodes), interdigitating cells of thymus, Langerhans cells in skin, and other APCs throughout the body.

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7
Q

Describe the relationship between phagocytes and the acquired system.

A

Phagocytic cells take in antigens, process them, and present them to the lympocytes of the acquired immune system so that a specific acquired immune response (cellular and humoral) can be initiated against that antigen.

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8
Q

(1) Describe the inflammatory response including (2) the hallmarks of inflammation and (3) which cells are involved.

A

Goal is to bring tissue back to normal. Triggered by exogenous or endogenous tissue damage.

Hallmarks: redness (rubor), pain (dolor), heat (calor), swelling (tumor) and loss of function

Cells: PMNs, macrophages and lymphocytes. PMNs show up in 30-60 mins. Mononuclears show up in 5-6 hours.

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9
Q

List the 3 main cell types involved in acquired immunity and briefly describe the function of each.

A

-T-cells: cell-mediated response. Direct attack on infected cells, tumor cells.
- B-cells: antibody production.
- Phagocytes: antigen processing and presentation.

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10
Q

Name the primary lymphatic organs and the type of cell that matures in each.

A

Thymus: maturation of T-cells
Bone marrow: origin of lymphocytes and maturation of B-cells.

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11
Q

Name the 2 major secondary lymphoid organs and 2 major functions that occur in these organs.

A
  • Spleen
  • Lymph nodes

(1) trap and concentrate foreign antigens, and (2) main site of production of antibodies and antigen-specific T-cells

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12
Q

Describe the circulation pathway of lymphocytes.

A

Circulate through blood, and enter lymphatic system. Re-enter circulation through thoracic duct, which empties into right atrium. Use HEV to “home in”, enter appropriate tissues through endothelial cell barrier.

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13
Q

Antigen

A

any agent capable of binding specifically to components of immune response.

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14
Q

Immunogen

A

any agent capable of producing an immune response.

All immunogens are antigens, but some antigens can bind without causing an immune response.

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15
Q

Hapten

A

Non-immunogenic low MW molecules

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16
Q

Adjuvant

A

present in vaccines and enhance immunogenicity.

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17
Q

Epitope/Antigenic determinant

A

5-7 AAs long and serve as antibody binding sites. Do not “fit” into the conformation or chemical makeup of body’s constituents.

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18
Q

Valence

A

number of epitopes on a molecule

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19
Q

Cross reaction

2 definitions

A

An immunologic reaction in which cells or antibodies react with 2 molecules that have common epitopes but are otherwise dissimilar.

Cells or antibodies with specificity for 1 epitope react weakly with another epitope that structurally resembles it (but is not specific for it).

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20
Q

List the four requirements for immunogenicity.

A
  • Foreign to self
  • High MW
  • Chemical complexity
  • Degradability (in order survive and then to be presented)
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21
Q

List the 4 major classes of antigens and give an example of a diagnostically important antigen for each class.

A
  • Carboyhydrates—ABC antigens on erythrocytes
  • Lipids—cardiolipin
  • Nucleic acids—autoimmune response to DNA with SLE
  • Proteins—serum albumin
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22
Q

Contrast epitope recognition by B cells and T cells.

A

B cells use sIg (surface immunoglobulin) receptors to bind free, soluble antigen

T cells use TcR, which require processing and presentation in association with MHC

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23
Q

Contrast how foreign antigens entering the body through blood, skin and respiratory or gastrointestinal routes find their way to the lymphoid cells.

A

BLOOD: response initiated at spleen
SKIN: local inflammation; transport to lymph nodes by macrophages
GI: response initiated at MALT

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24
Q

examples of physiological barriers

A

skin and mucous membranes
fatty acids and low pH of sweat
sebaceous secretions
soluble proteins (interferons, complement)
respiratory tract (nasal hairs, cilia, cough reflex, mucus lining)
GI tract (salivary enzymes, low pH of stomach, enzymes in bile and small intestine)

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25
Q

4 PMNs

A

neutrophils, eosinophils, basophils and mast cells

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26
Q

macrophages activated by…

A

cytokines released primarily from T-cells

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27
Q

differentiate NKs from lymphocytes

A

slightly more cytoplasm, granules

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28
Q

NK express…
function

A

Express killer inhibitory receptors (KIR). KIR binds MHCI on normal cells and protects them from NK destruction. Tumor/virally infected cells have abnormal MHCI and cannot bind KIR. NK destroys them.

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29
Q

2 NK killing processes

A

(1) Creates pores in the membrane, causing lysis
(2) Triggers apoptosis.

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30
Q

trigger NK activity

A

IL-2
IL-12
interferons

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31
Q

endogenous inflammation causes (2)

A

uncontrolled immune response
abnormal clotting reactions.

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32
Q

inflammation releases vasoactive peptides, which cause… (4)

A

(1) smooth muscle contraction, (2) nerve stimulation, (3) endothelial cell contraction, and (4) expression of ECAMs (endothelial cell adhesion molecules) resulting in increased vascular permeability and recruitment of PMNs to the site.

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33
Q

liver proteins involved in inflammation. example.

A

acute-phase proteins
C-reactive protein binds to membranes of certain microbes and activates complement.

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34
Q

Immunization

A

generation of subsets of lymphocytes that can recognize an antigen upon a secondary exposure

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35
Q

regions and cells of thymus

A

Cortex contains immature cells. Medulla contains more mature cells (which have their specific receptor)

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36
Q

atrophy of thymus

A

fatty metamorphosis

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37
Q

required for lymphocytes to enter appropriate tissues

A

homing in

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38
Q

HEV

A

high endothelial venules

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39
Q

typical MW of immunogens

A

> 6000 Da

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40
Q

not good immunogens due to lack of variety

A

homopolymers

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41
Q

example of a hapten

A

cardiolipin

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42
Q

homologous cross reactions

A

occur when antigen and immunogen are the same substance

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43
Q

heterologous cross reactions

A

occur when substance that induces immune response is something other than the antigen you are trying to elicit the response against

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44
Q

cross reactions cause…

A

false positives

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45
Q

Antibody

A

Product of the immune system that imparts protection.

Belong to a protein class called globulins, collectively known as immunoglobulins. Exhibit a high degree of specificity, therefore one part of the molecule must be adaptable to a large variety of epitopes.

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46
Q

F(ab)

A

Product of papain degradation. Cuts above hinge. 2 F(ab) from each antibody.

47
Q

Fc

A

The “stem” of the “Y” below the hinge. Constant.

48
Q

Fd

A

Part of the heavy chains included on the Fab region.

49
Q

F(ab’)2

A

Product of pepsin degradation. Includes both Fab regions (cuts below hinge).

50
Q

Allotype

A

different forms of the same protein. Changes in only 1 or 2 AAs. Genetic differences between different people.

51
Q

Idiotype

A

different antigenic determinants expressed on variable regions.

52
Q

Isotype

A

Type of heavy chains. Defines 5 classes of Ig.

53
Q

Describe the structure of the immunoglobulin fragments resulting from cleavage with pepsin.

A

F(ab’)2. This contains both L chains and the Fd part of both H chains.

It lacks the Fc of H chains, and therefore cannot do things like fix complement. The remainder of the molecule is broken down into smaller segments.

54
Q

Describe the structure of the immunoglobulin fragments resulting from cleavage with papain.

A

2 F(ab), containing one L chain and Fd part of one H chain, and 1 F(c), containing remainder of the H chains.

F(ab) has only one antibody combining site, and F(c) cannot react with antigen but retains biological properties of the Ig molecule.

55
Q

Contrast the variable and constant regions of the heavy chains in terms of structure and function.

A

Differ in their antigenic activity, carb content, size and biological function. Variable regions define differences, constant regions offer the biological activity.

56
Q

IgG
- MW
- half life
- domains
- cross placenta?
- fix complement?
- location
- valence
- subclasses
- functions (5)

A
  • 150,000 Da
  • 23 days
  • 4 domains
  • crosses placenta
  • fixes complement
  • predominant in blood, lymph, CSF, other fluids
  • valence 2
  • 4 subclasses

Functions:
Can cause precipitation of multivalent soluble antigens. Opsonin. Activates complement. Neutralizes toxins and viruses. Immobilizes bacterial flagella and cilia by causing them to clump.

57
Q

IgM
- MW
- half life
- domains
- cross placenta?
- fix complement?
- location
- valence
- subclasses
- functions (4)

A
  • 900,000 Da
  • 5 days
  • 5 domains
  • does not cross placenta
  • fixes complement
  • predominantly in intravascular space
  • valence 5
  • no subclasses

Functions:
First Ig produced in an immune response, either to infection or immunization (acute phase antibody). Efficient agglutinating antibody (forms bridges between antigens that are too distant to be bridged by smaller IgG molecules). Natural isohemagglutinins (naturally occurring antibody against RBC antigens). Most efficient complement fixing antibody.

58
Q

IgA
- MW
- half life
- domains
- location
- valence
- subclasses
- functions (3)

A
  • 160,000 Da monomer, 400,000 Da dimer
  • 4-7 days
  • 4 domains
  • does not cross placenta
  • secretory antibody
  • 4 valence
  • 2 subclasses

Functions:
Provides protection to neonate through breastmilk. can prevent attachment of organisms to cells and thus provide defense to local infections in the respiratory and GI tracts. Prevents viruses from entering host cells. Good agglutinating antibody.

59
Q

IgE
- MW
- half life
- domains
- location
- valence
- subclasses
- functions

A
  • 200,000 Da
  • 2 days
  • 5 domains
  • low in serum, stays bound to B-cells
  • 2 valence
  • no subclasses

Functions:
“Reaginic”, protects against parasitic infections and binds to mast cells which causes hypersensitivity (allergies).

60
Q

IgD
- MW
- half life
- domains
- location
- valence
- subclasses
- functions

A
  • 180,000 Da
  • 2.8 days
  • 4 domains
  • surface of maturing B-cells
  • valence 2
  • subclasses unknown

Functions:
Unknown in serum. Does not appear to have a protective function. Does it have a function in B-cell maturation?

61
Q

Compare and contrast IgG and IgM in terms of protection against infection and in which stage of infection they appear.

A

IgM made first. Isotype switching occurs later, and B-cells begin to make IgG. During second exposure, a small amount of IgM is made and a huge amount of IgG is made.

62
Q

Explain why IgM is the best agglutinating antibody.

A

Highest valence.

63
Q

Assess the usefulness of analyzing fetal or newborn serum for IgG and IgM antibodies.

A

Any fetal IgM indicautes intrauterine infection; does not cross placenta.

3-4 months gestation shows a rapid increase in mother’s IgG concentration.

5 months gestation IgM and IgA fetal synthesis begins.

3-6 months after birth, maternal IgG is gone, and the baby must produce its own.

64
Q

percentages of light chain types

A

60% kappa
40% lambda

65
Q

domains

A

segments of antibody created by the interchain bonds

66
Q

hinge region found between…

A

CH1 and CH2

67
Q

AAs present in hinge region

A

Cys and Pro

68
Q

structure that allows crosslinking

A

hinge region

69
Q

Serology

A

utilization of the in vitro reaction between antigen and serum antibodies.

Usually looking for antibody in patient serum, not antigen.

70
Q

Monoclonal antibodies

A

highly specific reagents consisting of homogeneous populations of antibodies, all with precisely the same specificity toward an epitope.

71
Q

Association constant

A

characterizes binding of an antibody with an epitope, expressed by:

K=[AbH]/[Ab][H]

Where H = hapten or antigen.

72
Q

Affinity

A

initial force of attraction between Fab and a single epitope.

73
Q

Avidity

A

overall binding energy between antibody and multivalent antigen.

74
Q

Zeta potential

A

electrical charges on surfaces of particles

75
Q

prozone

A

antibody excess that can prevent agglutination or precipitation

76
Q

equivalence zone

A

proportion of antibody:antigen is optimal for precipitation

77
Q

postzone

A

more antigen than antibody

78
Q

Give 3 examples of primary antigen-antibody interactions.

A

Van der waals forces
electrostatic forces
hydrophobic forces

79
Q

Summarize how cross-linking formation occurs, including the antigen and antibody requirements necessary for it to occur.

A

interactions between multivalent antigens and antibodies that have at least 2 combining sites per molecule

(also: secondary interactions)

80
Q

Give examples of some of the physical conditions that can influence antigen-antibody association and state how they would affect the interaction (ie: hinder or enhance).

A
  • pH
  • incubation time
  • ionic strength
  • steric hindrance
  • shielding effects (Na and Cl)
  • temperature (IgM cold-reacting, IgG warm-reacting)
81
Q

Give 3 examples of secondary antigen-antibody interactions.

A

agglutination
precipitation
complement activation

82
Q

Compare and contrast direct vs. passive agglutination.

A

Direct agglutination: cross-linking of insoluble particulate antigen with antibody, resulting in visible clumping.

Passive agglutination: cross-linking of antibody with soluble antigen attached to an insoluble particle (latex, RBCs, etc).

83
Q

Compare and contrast agglutination, precipitation and flocculation.

A
  • Agglutination: antigen is a particle or attached to a particle (insoluble).
  • Precipitation: antigen is soluble.
  • Flocculation: interaction of soluble antigen with antibody, which results in the formation of a fine precipitate
84
Q

Examples of flocculation assays

A

RPR and VDRL assays for syphilis

85
Q

precipitin reaction

A

When the lattice reaches a certain size, the Ab-Ag complex loses its solubility and precipitates out of solution

86
Q

2 assays with precipitate in solution and difference between them

A

Turbidimetry: Detector is in direct line with incidence light. Measures reduction in light intensity due to reflection, absorption or scatter due to the precipitate.

Nephelometry: Measures light scattered at a certain angle between detector and incident light.

87
Q

Explain double diffusion.

A

Antigen and antibody are placed in separate wells and each diffuses outward from the wells (toward each other) until they reach an equivalence point, at which they precipitate out of solution and form a precipitin band.

88
Q

3 patterns of double diffusion results

A

Identity
Non-identity
Partial identity

89
Q

Explain radial immunodiffusion.

A

Well contains antigen at different concentrations and antibodies are distributed uniformly in agar gel. Precipitin ring forms instead of precipitin band. The diameter is directly proportional to the amount of antigen in the sample. Uses known standards to create a curve.

90
Q

3 sources of error in immunodiffusion assays

A

(1) overfilling wells, (2) nonlevel incubation or inadequate incubation time, and (3) drying out or contamination of gels.

91
Q

4 sources of error in electrophoresis

A

(1) application of current in the wrong direction or wrong voltage, (2) incorrect pH, (3) incorrect time, and (4) incorrect concentration of antigen and antibody.

92
Q

explain radioimmunoassay (RIA)

A

type of direct-binding immunoassay which uses isotopically labeled molecules (typically anti-human-antibody).

93
Q

explain solid-phase immunoassays.

A

protein antigens are adsorbed onto a surface (ie. polystyrene bead). Patient antibody reacts with the antigen. Anti-human-antibody (conjugate) labeled with an enzyme are added which then bind to the antibody bound to the solid phase.

94
Q

Utilizes fluorescent-labeled antibodies to detect antigen or antibody.

A

immunofluorescent assay (IFA)

95
Q

most common fluorochormes used in IFA

A

FITC (fluorescein isothiocyanate), which fluoresces apple green color
TRITC (tetramethyl rhodamine isothiocyanate), red orange color

96
Q

Direct vs Indirect IFA

A

Direct IFA involves reacting patient tissue on a slide (ie. skin or kidney biopsy) with fluorochrome-labeled specific antibodies.

Indirect IFA involves reacting the patient serum (antibody) with a tissue or cell culture substrate on a slide, and then adding a fluorochrome-labeled anti-human-antibody conjugate.

97
Q

explain immunochromatographic assay

A

the analyte is applied at one end of the strip and migrates by capillary action to the other end. As it migrates, the patient antigen binds with its specific antibody that has a colored label attached. Further down the strip a monoclonal antibody captures this complex to immobilize it to show a colored line.

98
Q

immunochromatographic assay is a type of….

A

rapid immunoassay

99
Q

Explain immunofixation electrophoresis.

A

serum is placed in a well of a gel and an electric current applied to separate the proteins, then the proteins are precipitated into the gel with specific anti-serum, and stained for visualization.

99
Q

radial immunodiffusion detects…

A

antigen

99
Q

explain western blots.

A

antigens or a mixture of antigens are separated by electrophoresis in a gel. Separated material is then “blotted” onto nitrocellulose sheets, and antigen binds tightly. Patient serum containing antibody is applied to the sheet and binds specifically to the antigen. The strip is washed with anti-human-antibody (binds to any antibody) and stained for visualization of bands, and band pattern is compared to a control.

99
Q

Immunofixation electrophoresis is used to detect…

A

monoclonal antibodies

100
Q

Visualize antibody structure

A
101
Q

Visualize pepsin vs papain degradation.

A
102
Q

Primary vs secondary exposure, IgM vs IgG

A
103
Q

Visualize types of Ig differences

A
104
Q

Precipitin curve

A
105
Q
A

Immunofixation electrophoresis

106
Q
A

Western blot

107
Q

Indirect vs Sandwich ELISA

A
108
Q
A

Direct IFA

109
Q
A

Indirect IFA

110
Q

Visualize immunochromatographic assay

A