2.7 Flashcards by Mallory Housman

what antibodies are in saliva

SIgA & IgG

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what is the function of the antibodies in the oral cavity

limit bacteria adherence

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what do B cells express

B cell receptors (BCR)

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how are BCRs formed

by membrane-bound antibodies in association with invariant membrane proteins Ig alpha and Ig beta

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how do BCRs recognize antigens

via membrane Ig

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how do BCRs transmit signals

via Ig alpha and Ig beta

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what is an isotype based on

the heavy chain

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T cells and B cells recognize different forms and types of antigens and B cells may or may not need T cells to be activated. What is the specificity of B cells that develop in a T cell-dependent manner?

a - nucleic acid
b - lipid
c - protein
d - polysaccharide
e - hapten alone

c - protein

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what Ig’s are monomeric with 2 binding sites

IgD, IgE, & IgG

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what Ig is pentameric with 10 binding sites

IgM

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what Ig is mainly dimers with 4 binding sites

IgA

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what is the structure of immunoglobulin

y shape molecule formed by 2 heavy chains and 2 light chains

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what are the two forms that immunoglobulin can exist in

membrane-bound or secreted

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what do variable regions contain

antigen-binding sites

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what does the constant region of Fc region mediate

effector function

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what is the function of the constant region of the Fc region

determine isotype
bind complement
bind Fc receptors

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what is defined as the variable domains of light and heavy chains

binding site

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an antibody binds a wide variety of antigens including what types

proteins
lipids
polysaccharides
nucleic acid

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what is recognized by the antibody

the native not processed antigen

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what is defined as the antigen part recognized by an antibody

epitope

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how is the diversity of BCR generated?

recombination of Ig gene segments and junctional diversity

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what does the heavy chain locus contain

V, D, J, & C genes

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what does the light chain locus contain

V, J, & C genes

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what does C gene organization lead to production of

IgM

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what is the first C region cluster

Cµ

recombination of immunoglobulin genes involves

random selection of segments

what is the first antibody to be produced by the C gene

IgM

what is immunoglobulin gene recombination mediated by

recombinase (RAG) specific for VDJ

what does RAG deficiency lead to

SCID - bubble boy

the combinatorial diversity of Ig is ___

limited

the junctional diversity of Ig is ___

unlimited

what impacts junctional diversity

- exonucleases - terminal deoxyribonucleotidyl transferase (TdT)

Ig has tremendous ____ but produces ____

- diversity - nonfunctional genes

maturation of lymphocytes involve steps of ___ and ___

- proliferation - receptor expression

immature cells that do not ___ functional receptors die by ____

- rearrange - apoptosis

____ undergo negative or positive selection

mature cells

what is checkpoint 1 for B cell maturation

pre-BCR

what is checkpoint 2 for B cell maturation

IgM

selection of immature B cells occurs in the ___ in an antigen-independent manner

bone marrow

expression of ___ promote survival of B cells & proliferation and triggers recombination of the light chain locus & IgM expression

pre-BCR

signals from ___ promote survival of B cells

IgM

what does receptor editing involve

light chain recombination

what is the result of receptor editing

change of the Ig specificity

what is the advantage of receptor editing

B cells are not eliminated

____ eliminates immature B cells that can bind with high affinity ubiquitous self antigens

negative selection

____ results in clonal expansion and differentiation

antigen recognition

where do plasma cells producing high affinity Ig migrate to

bone marrow or mucosal tissues

how long do plasma cells producing high affinity Ig survive

years

_____ do not secrete Ig

memory B cells

what lasts a lifetime in mucosal tissues and blood with no restimulation

memory B cells

what distinguish B cells from T cells? a - BCR diversity is not achieved by random rearrangement b - selection of B cells depends on antigen recognition c - expression of pre-BCR in contrast to pre-TCR induces cell survival d - receptor editing only occurs for B cells e - T cells recognize native proteins

e - T cells recognize native proteins

what antibody response is quicker, larger, has higher affinity, and more abundant IgG

secondary

what provides signal 2

innate immune signals

what does signal 1 involve

engagement of antigen receptor

what does signal 2 involve

engagement of CR2 or TLR enhancing B cell activation

what delivers the CR2 activating signal

CD19 & CD81

what type of antibody response is to protein antigens

T dependent

what type of antibody response is to nonprotein antigens

T independent

what type of antibody response involves isotype switching

T dependent

what type of antibody response involves IgM

T independent

what type of antibody response involves high affinity Ig

T dependent

what type of antibody response involves low affinity Ig

T independent

what are small molecules that cannot elicit an immune response by themselves but do so after binding to larger proteins or cells

haptens

___ process antigens

B cells

T/F B cells and T cells recognize different epitopes of the same protein

true

native conformational epitopes are recognized by ___

B cells

peptide fragments are recognized by ___

T cells

what does recognition of peptides presented by B cells induce

CD40L upregulation in T cells & production of cytokines

engagement of CD40 and cytokine receptors on B cells lead to their ____ and ___ in plasma cells

- proliferation - differentiation

what occurs in the germinal center?

- isotype switching - affinity maturation - selection of high-affinity B cells

what induces isotype switching

change in the constant region of the heavy chain with no change in specificity

what does isotype switching require from Tfh cells

CD40L

how is the type of heavy chain isotype determined

by the cytokines produced by Tfh cells (IgG & IgE) or tissues (IgA)

T/F in switch recombination the specificity of the Ig changes

false - does NOT change (same V region)

in switch recombination what is different and what does it reflect

- C region - function of the Ig

what results in the deletion of Cµ gnee

activation-induced cytidine deaminase (AID)

activation-induced cytidine deaminase results in recombination bringing ___ next to a different ___

- VDJ exon - C gene

how are FDC different from classical dendritic cells

- different progenitor - no processing of antigen - no binding of antigen to MHC molecules

what do high-affinity B cells interact with

- follicular DC that display antigens - Tfh that promote survival via CD40-CD40L