Antibody Production/Class Switching

General

100

In T-cell dependent responses, some activated B cells produce other antibodies besides IgM in this process

Isotype (class) switching

200

Activated B cells produce antibodies that bind to antigens with increasing affinity in this process

Affinity maturation

300

An example of a stimulus that can activate B cells without T cell assistance 

Polysaccharides

400

T-independent responses are rapid but simple, consisting mostly of these

Low-affinity IgM antibodies

500

B cell activation is facilitated by this coreceptor on B cells, which recognizes complement fragments that are covalently attached to the antigen or are part of ICs containing the antigen

CR2

In need of a friend

100

Expressed on the surface of activated T cells and homologous to TNF; required for T-dependent B cell activation

CD40L

200

Mutations in CD40L result in this disease

X-linked hyper-IgM syndrome

300

True or False: T-cell mediated dendritic cell and macrophage activation involves the interaction of CD40L on activated T cells and CD40 on DCs and macrophages

True

400

Activated B cells outside of the follicle induce activated T cells to differentiate into Tfh cells, which express high levels of CXCR5.  These are drawn into lymphoid follicles by this ligand

CXCL13

500

The defining cytokine produced by Tfh cells; required for germinal center development and contributes to the generation of plasma cells

IL-21

Say my name

100

Mutations in ATM

Ataxia-telangiectasia

200

Artemis, DNA ligase IV, Cernunnos, Nijmegen breakage syndrome

Radio-sensitive SCIDs

300

SLAM-associated protein (SAP) signaling stabilizes expression of transcription regulators required for Tfh cell development; mutations in SAP lead to this

X-linked lymphoproliferative syndrome

400

While usually not monogenic, mutations in TACI, BAFF, ICOS, CD19, LRBA can cause this

CVID

500

This resembles X-linked agammaglobulinemia more than HIGM in that patients are susceptible to bacterial infections only 

AID deficiency (also accept UNG deficiency in ddx)

Time to switch

100

These antibodies are made without class switching

IgM and IgD

200

Th2-type cytokines that drive isotype switching from IgM to IgE

IL-4 and IL-13

300

Key enzyme required for isotype switching and somatic hypermutation

AID

400

AID removes an amino group from cytosines in ssDNA templates, converting cytosine to this

deaminated uracil (C-->U)

500

UNG removes U residues to create "abasic" sites for this endonuclease to then create nicks to allow for double-stranded DNA breaks

APE1