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Immunology > Lectures 5 - Antibody Structure and Function > Flashcards

Lectures 5 - Antibody Structure and Function Flashcards

1
Q

Resting B cell contains _____ on its membrane

A

Ig (acts as receptor for bacterial antigen)

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2
Q

Epitopes, a.k.a. ________, are part of what molecules?

A

Antigenic Determinants

Part of antigen (that antibody binds to)

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3
Q

Most antigens have ___ epitopes, which makes them _______

A

multiple epitopes

Multivalent

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4
Q

Epitopes are usually what types of molecules?

A

CHO or peptides

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5
Q

Vaccine antigens molecule-type examples?

A
  • bacterial proteins & polysaccharides
  • virus like particles
  • whole bacteria
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6
Q

Epitopes recognized by antibodies are usually located…

A

on the antigens surface

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7
Q

Antibodies (& B cells) can bind to ______ epitopes.

T cells can bind to ______ epitopes

A
  • B cells = Linear or discontinuous
  • T cells = Linear Only
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8
Q

Haptens are small molecules that _______, but can bind to __________.

A

Not immunogenic themselves, but can bind to Ig’s or TCR’s

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9
Q

Haptens can induce immune response when…

A

Linked to a larger protein carrier

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10
Q

Example of clinical hapten

A

Penicillin

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11
Q

Penicillin two mechanisms

A
  • Binds to bacterial transpeptidase and inactivates it
  • Modifies proteins on human RBC to create foreign epitopes
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12
Q

B cells are activated by _____ and ______

A

antigen and activated TH2 cells

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13
Q

Plasma cells secrete ___________ which binds to _________

A

Penicillin-specific IgG which binds to modified RBCs

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14
Q

Chains of Ig molecule:

A

2 Light chains (lambda and kappa)

5 Heavy chains (mu, gamma, alpha, epsilon, delta)

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15
Q

Ig domains are linked by

A

disulfide bonds

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16
Q

The antigen binding part of the Ig molecule is the _____ terminus

A

N terminus

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17
Q

Ig variable region, a.k.a…

A

Antigen binding site

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18
Q

Effect of papain on Ig molecule

A

Proteolytically cleaves into 2 FAB and 1 FC domains

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19
Q

Fab domain aka…

A

antigen binding fragment

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20
Q

Fc domain aka

A

crystallizable fragment

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21
Q

proteolytic cleavage of Ig by pepsin does what?

A

Creates F(ab’)2 domain and multiple fragments of the constant domain

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22
Q

Disulfide bonds of Ig molecule are present at ….

A

hinge region

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23
Q

Fragments (names) that comprise the antigen binding sites of Ig molecule

A

Vh + Ch1

CL + VL

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24
Q

Domains (names) that make up the constant part of the Ig molecules

A

CH2 and CH3

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25
Q

Fab structure is comprised of many passes of ________ joined by ______

A

Beta strands

joined by loops

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26
Q

Hypervariable region = CDR = ___________

A

complementarity-determining region

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27
Q

L chain is made of ______ or ____

A

Kappa or Lambda

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28
Q

Ig isotypes are the same thing as _____. Examples?

A

Classes

M, D, G, E, A

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29
Q

Ig Isotypes, allotypes, and Idiotypes differ in their….

A

Isotypes = differ in heavy chain (Mu, Gamma, Delta, Epsilon, Alpha)

Allotypes may have variations in amino acids in constant regions of heavy or light chain.

Idiotypes differ in hypervariable region. Recognize different epitopes.

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30
Q

Allotypes’ differences may affect…

A
  • half life
  • subclass distribution
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31
Q

Allotype genetics display what three things?

A
  1. mendelian inheritance (autosomal dominant)
  2. Variations among ethnic groups
  3. associations with infectious diseases and AI diseases
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32
Q

___ and ___ domains of Ig interact with antigen

A

Vh and VL

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33
Q

Antigen and antibody interactions type

A

Non-covalent binding (Electrostatic, H bonds, VDWF, Hydrophobic)

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34
Q

Affinity definition

A

Strength of interaction between epitope and one antigen binding site

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35
Q

Noncovalent Ag-Ab binding forces are ____ forces

A

Short range forces

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36
Q

Avidity definition

A

Sum of interactions between antibody and antigen

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37
Q

Crossreactivity can occur between ________

Example?

A

antigens that share epitopes

Influenza (H2N2, H2N3)

38
Q

Two steps to make MABs

A
  • Immortalization of a single clone of antibody-secreting cells
  • Fusion of B cells with neoplastic plasma (myeloma) cells
39
Q

In making MAB’s, after growing in drug-containing medium, only __________ survive.

What do you then select for?

A

hybrid cells

Select for antigen-specific hybridoma and clone them

40
Q

Polyclonal vs monoclonal origin

A

Poly = purified from serum of immunized animals (goats/rabbits)

Mono = Made from immortalized plasma cells (mouse origin)

41
Q

Polyclonal vs Monoclonal specificity/affinity

A

Poly = multiple, Mono = single

42
Q

Polyclonal vs Monoclonal supply

A

Poly varies from batch to batch

Mono gives an unlimited supply of identical molecules

43
Q

-ximab suffix

A

Chimeric

44
Q

-zumab suffix

A

humanized

45
Q

-umab suffix

A

human

46
Q

Four types of therapeutic MAB’s

A

Mouse, chimeric, humanized, human

47
Q

Psoriasis MAB name and target

A

infliximab

anti-TNF

48
Q

7 types of immunoassays

A

Precipitation, Agglutination, ELISA, RIA, Western blot, Immunofluorescence

49
Q

Most - to - least sensitive immunoassay (3)

A

Precipitation (least)

Agglutination

RIA and ELISA

50
Q

Aggretates are formed between the interaction of ______ and ________.

What does the precipitation curve look like between these two things?

A

multivalent antibodies and macromolecular antigens

If antibody or antigen in excess, there is a lower precipitation rate (Precipitation peaks when they are equal)

51
Q

Antigens can have several _______ that bind to antibodies.

This is separate from the __________, which tells us how many antibodies will bind

A

epitopes

antigen valence

52
Q

____ can form between RBC and antibodies. This is called _______

A

Immune complexes

Hemagglutination

53
Q

A ___ type RBC will show no agglutination with any antibody molecule

A

Type O

54
Q

Hemagglutination occurs with what type of Antibody?

A

IgM

55
Q

What is Coomb’s reagent?

What is its purpose?

A

Anti-human immunoglobulin antibodies

Add it to RBC cells to test for agglutination (will occur if the RBC has antibodies on its coat)

56
Q

With a direct Coomb’s test, you must add a _________ to induce agglutination

A

secondary reagent

57
Q

Why can’t IgG’s complex in a coomb’s test?

A

The negative surface charge would prevent complexing with an RBC

58
Q

Describe the three steps of the indirect Coomb’s test

A
  1. Incubate test serum with RBC
  2. Wash RBC
  3. Add anti-human Ig antibodies
59
Q

Direct coomb’s test is done _____, and indirect coomb’s is done _______

A

Direct = In vivo

Indirect = in vitro

60
Q

Rhesus factor is a problem when mom/baby are…

A

When mom is Rh-, and baby is Rh+

Mom makes antibodies against baby’s Positive rhesus factor

61
Q

Direct vs indirect Coomb’s in Rh+/- situation

A

Direct = add antibodies to washed RBC

Indirect = Add RBC’s to maternal serum, then wash away unbound antibody

62
Q

4 steps in ELISA

A
  1. Coat wells with antigen
  2. Add serum sample
  3. Add enzyme-labeled anti-human IgG (labeled with color-producing enzyme)
  4. Add substrate (for the enzyme)
63
Q

5 steps of Western blot (HIV example)

A
  1. Dissociate the virus in SDS
  2. Run particles on SDS-PAGE gel
  3. Transfer to **Nitrocellulose **
  4. Overlay with antiserum
  5. Use enzyme-linked anti-IgG to detect the bound antibody
64
Q

Immunofluorescence works because the ______ is linked to ______.

A

Antibody is linked to a fluorochrome that emits light

65
Q

Briefly sum up Flow cytometry process.

What does this allow us to see?

A
  • A stream of fluid drops containing antibody-labeled cells are detected by a “laser”
  • It allows us to quantify populations of cells based on which antibody (and fluroescence molecule) is bound to its surface
66
Q

Example of use of flow cytommetry (for cell populations)

A

CD4 and CD8 T cells (expression of one, both, or neither will differentiate)

CD3 & CD19 B cells (++, +/-, –)

67
Q

AIDS asymptomatic phase begins with what event?

A

Seroconversion

68
Q

What are the segments in heavy and light chain loci?

A

V = Variable

J = Joining

C = Constant

D = Diversity

69
Q

The first two gene segments of the light chain to join are the _____ and __ segments. This is called _______.

This process takes place at the level of _______.

A

V, J

Somatic recombination

DNA

70
Q

How is the light chain C region joined to the V(J) region exon?

A

RNA splicing gets rid of the introns between L/V and J/C, creating a

71
Q

The light chain contains what gene segments?

A

VL and CL

72
Q

Heavy chain contains what segments?

A

VH, CH1, CH2, CH3

73
Q

Heavy chain C segments are joined by _____

A

RNA splicing

74
Q

Heavy chain contains _____, (not present in the light chain)

A

Diversity (D) segment

75
Q

Which segments are the first to join in the heavy chain?

What is this process?

A

D/J join first

Somatic recombination (of DNA)

(V–>DJ happens in second step)

76
Q

When does somatic recombination occur?

A

When the cell differentiates into a B cell?

77
Q

Which gene segment has the greatest amount of variability in the human genome?

A

Variable (V) segments

78
Q

L, K, and Heavy chain genes contain _____ and ______ sequences, which allow for specificity by…

A
  • Recombination Signal Sequences (RSS)
  • Spacer Sequences

….allow for the spacers to only recombine 12 & 23

79
Q

For spacer sequences in the heavy chain, ___ can only be combined to ___, not ___.

This happens d/t ________ sequences located between the V and J segments

A

12+23

23 can’t bind 23

80
Q

Recombination is mediated by _______.

_____ is part of this enzyme complex

A

V(D)J Recombinase

RAG

81
Q

RAG binds to _____, and facilitates excision of a DNA segment, creating a _____and a ______

A

RSS sequences

Creates a Signal Joint and a Coding joint

82
Q

RAG cleaves a ______ from the D and J segments to make ______

RAG forms a _________ by nicking one of the sequences of DNA

A

heptamer (RSSs), DNA hairpins

pallindromic P nucleotides

83
Q

Function of TdT in junctional diversity?

A

it adds N-nucleotides in a random manner

84
Q

What happens after the D and J strands are paired during junctional diversity?

What is the function of this?

A

Exonuclease cleaves out unpaired nucleotides

This generates further diversity

85
Q

Equation for calculation of diversity of a chain? (K, L, or Heavy chains)

A

V x #J ** = #Vκ**

For light chain (e.g. Kappa)

For Heavy chain:

This shows us that D segments yield a huge amount of diversity

86
Q

Two other factors (other than the VDJ variants) that contribute to increased diversity?

A
  • Imprecise joining
  • Addition of N nucleotides by TdT
87
Q

(E.g. heavy chains) VDJ is the ___ domain, while rearrangement of many C gene segments makes up the ____ domain

A

VDJ = Variable

C = Heavy chain

88
Q

Heavy chain gene rearrangement (C segments) determine…

A

the isotype of the Ig molecule

89
Q

Naive B cells co-express ____ and ____.

This is due to ___________

A

IgM and IgD

RNA splicing (NOT DNA REARRANGEMENTS)

90
Q

Number of Constant (C) and VDJ domains in IgM and IgD heavy chains

A

IgM = 4 C regions

IgD = 3 C regions

Both have one VDJ region

91
Q

The B cell receptor is composed of what (three) things?

A

Ig molecule

Igß and Ig@

Immunology (10 decks)

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