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Immunology and Microbiology > Chapter 4 - B cell (Exam 3) > Flashcards

Chapter 4 - B cell (Exam 3) Flashcards

1
Q

Functions of antibodies

A
  1. Recognize and bind antigens
  2. Target bound antigen to other cells
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2
Q

Number of Ab molecules one can produce is limited by

A

Number of B cells

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3
Q

Before antigen binding

A

Ig is bound to B cell surface receptor

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4
Q

After antigen binding

A

B cell proliferates and differentiates into plasma cell
Secretes antibody

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5
Q

Different antibody structures

A

Light + Heavy
Variable + Constant

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6
Q

Fab fragment

A

Fragment antigen binding

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7
Q

Fc fragment

A

Fragment crystallizable

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8
Q

Proteolytic cleavage

A

Two Fab and one Fc

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9
Q

5 isotypes of heavy chains

A

IgG, IgM, IgD, IgA, IgE

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10
Q

Secreted as monomers?

A

IgG, IgD, and IgE

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11
Q

Secreted as monomer and dimer?

A

IgA

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12
Q

Secreted as pentamer?

A

IgM

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13
Q

What are the two isotypes of light chains?

A

kappa and lambda
each antibody has EITHER one

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14
Q

H and L chains arranged in

A

immunoglobulin domains

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15
Q

Differences in ____ lead to variability and different binding properties in light chains.

A

Loops

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16
Q

Globular

A

Soluble in aqueous environment
-hydrophilic aa out
-hydrophobic aa in

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17
Q

Immunoglobulin-like domain

A

present in other proteins as well
immunoglobulin superfamily

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18
Q

Hypervariable regions (HV)

A

major differences in aa sequences reside
Complementary determining regions (CDRs)

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19
Q

Framework regions (FR)

A

low variability in amino acid sequence

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20
Q

Types of antigen binding sites

A

Pocket
Shallow groove
Extended surface
Protrusion

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21
Q

Antigen binding sites

A

Non-covalent forces bind chemical groups in antigen to amino acids of Ab

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22
Q

Non-covalent forces

A
  1. electrostatic interactions
  2. hydrogen bonds
  3. van der waals forces
  4. hydrophobic interactions
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23
Q

what do antibodies recognize?

A

proteins, carbohydrates, glycoproteins, proteoglycans, glycolipids, etc

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24
Q

antibodies recognize _______________ on he outer surface

A

native structure

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25
Q

B cell differentiates into a ___________ which secretes ____________

A

plasma cell

antibody

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26
Q

epitope

A

antigenic determinant

part of antigen to which antibody binds
cluster of amino acids

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27
Q

antibodies are most effective at binding

A

surface epitopes

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28
Q

multivalent antigen

A

more than 1 epitope

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29
Q

antibody epitopes can be

A

linear or discontinuous

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30
Q

polyclonal antibody

A

different antibodies recognize different epitopes

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31
Q

monoclonal antibody

A

same antigens, same epitope

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32
Q

way to produce antibodies in research

A

immunize an animal, collect antisera from blood (pure) and produce polyclonal antibodies

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33
Q

monoclonal antibodies in research

A

B cells from mouse and tumor cells fused together
select antigen specific hybdridoma and grow in large numbers

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34
Q

uses of antibodies in research

A

identify many unknown surface proteins
monitor specific surface protein expression

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35
Q

flow cytometry

A

use of fluorescent antibodies to measure cell population in blood
detect diseases

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36
Q

antibodies in the clinic are used to _______

how?

A

treat diseases

inject mouse antibodies into deficient patients, prevent transplant rejection

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37
Q

modifications to mouse monoclonal antibodies to prevent human immune system attack

A

chimeric

humanized

human

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38
Q

chimeric modifications

drug example

A

mouse V regions, human C region

rituximab - lymphoma

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39
Q

humanized modifications

drug example

A

mouse CDRs, all other sequences human

omalizumab - allergic asthma

40
Q

human modifications

drug example

A

completely human antibody sequence
antibody from mice to have human Ig genes

adalimumab (HUMIRA)

41
Q

another name for human modifications is

A

human hybridomas

42
Q

ELISA

A

enzyme linked immunosorbent assay

measures concentration of an antibody/antigen that can bind to an antibody

43
Q

quantification of ELISA

A

absolute concentration or antibody titer

44
Q

RIA

A

radioimmunoassay

measures the concentration of an antibody/antigen that can bind an antibody

45
Q

coombs test

A

tests for presence of antibodies and complement that can bind to RBCs

results in red blood lysis/anemia

46
Q

western blot

A

detects presence of a single protein in a complex mixture of proteins

47
Q

immune system needs to generate a _______ population of antibodies that can recognize any pathogen at infection site and target it for destruction

48
Q

what happens before antigen binding?

A

generate billions of B cells
containing a surface immunoglobulin with a unique variable region

49
Q

what happens after antigen binding?

A

secrete antibody
modify variable region to bind more tightly
switch heavy chain

50
Q

why do we switch heavy chain after antigen binding?

A

to eliminate the pathogen most effectively

51
Q

things that happen before antigen binding

A

somatic recombination
junctional diversity
combination of different heavy chains and light chains

52
Q

antibodies cannot be _________ until they are __________

A

expressed

rearranged

53
Q

light chain variable region contains

A

variable (V) and joining (J) segments

54
Q

heavy chain variable region contains

A

variable (V), joining (J) and diversity (D) segments

55
Q

rearranged V, D and J segments encode for

A

CDR loops of antibody

56
Q

do constant regions have to be rearranged?

57
Q

which constant region determines the isotope of the antibody?

A

the closest one

58
Q

somatic recombination

A

random rearranging of antibodies

59
Q

how many rearrangements in light chains?

A

1 (V-J joining)

60
Q

how many rearrangements in heavy chains?

A

2 (DJ, V-DJ joining)

61
Q

enzyme responsible for the recombination of genes

A

VDJ recombinase

62
Q

examples of recombination activating genes

A

RAG-1 and RAG-2

63
Q

what is involved in the recombination of genes?

A

VDJ recombinase
recombination activation genes
DNA repair enzymes

64
Q

junctional diversity

A

2 sets of new nucleotides are randomly added (P and N)

65
Q

Severe Combined Immunodeficiency (SCID)

A

genetic deficiencies RAG enzymes

B and T cells are not produced

66
Q

3 contributions to antibody diversity

A

antibody DNA gene segments are randomly combined

additional nucleotides are inserted at junctions during somatic recombination

separate B cells have the same rearranged heavy chains with different rearranged light chains

67
Q

allelic exclusion

A

only 1 allele for each is rearranged and expressed in a single B cell

68
Q

allelic exclusion ensures that each B cell produces

A

antibody of a single antigen specificity

69
Q

allelic exclusion allows for

A

clonal selection against only 1 pathogen

70
Q

things that happen after antigen binding

A

surface Ig vs Secreted Ab

somatic hypermutation

isotope switching

71
Q

first form of Ig is

A

membrane bound

72
Q

membrane bound Ig

A

transmits signal of antigen binding to Ig into cell interior with the help of Iga and Igb coreceptors

73
Q

after antigen binding, Ig is

A

secreted as antibody (plasma B cell)

74
Q

somatic hypermutation

A

random introduction of single nucleotide mutations through entire rearranged V region DNA

75
Q

somatic hypermutation is performed by the enzyme

A

AID (activation induced cytidine deaminase)

76
Q

AID causes a __________ and is made only by _____________

A

point mutation

proliferating B cells

77
Q

result of somatic hypermutation

A

B cells with mutant surface Ig

78
Q

somatic hypermutation leads to

A

selection of antibodies with higher affinity for infection pathogen

79
Q

isotope switching

A

splice out C region of previous isotope

80
Q

what antibody is made in the primary immune response?

81
Q

why does the isotope need to switch from IgM?

A

so the antibodies can eliminate the pathogen properly

82
Q

isotope switching depends on the

A

AID enzyme

83
Q

switch region

A

highly repetitive DNA

facilitates recombination

84
Q

switching can occur

A

from m to any other isotype or sequentially

85
Q

Hyper IgM immunodeficiency

A

no somatic hypermutation/class switching

only low affinity IgM in large amounts

86
Q

antibody effector functions

A

neutralization cells
opsonization
complement activation
recruiting NK cells to kill
sensitization of mast cells

87
Q

what determines antibody effector functions?

88
Q

IgM

A

pentameric
low affinity, high avidity

89
Q

avidity

A

overall strength of multiple binding sites

90
Q

IgG

A

smaller, more flexible
transferred across placenta during pregnancy

91
Q

IgA

A

secreted as monomer in blood, dimer in mucosal surfaces
in lymphoid tissue under mucosa
in lumen of gut and in milk, saliva, sweat, tears

92
Q

what is the most abundantly produced Ig?

93
Q

IgE

A

binds to mast cells, eosinophils, basophils
eradicates parasites/response to allergen

94
Q

IgG antibody has the most _______ functions

why?

A

diverse

hinge, elbow and tail regions give IgG flexibility

95
Q

IgG has ______ different subclasses and they differ in _________________

A

four (G1-G4)

structure of the hinge

96
Q

IgG4 can exchange

A

1 heavy and light chain in circulation (functionally monovalent)

97
Q

because IgG4 is functionally monovalent, it

A

can reduce immune response

is elevated in allergic individuals

Immunology and Microbiology (22 decks)

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