15: Humoral Immunity Flashcards
Follicular vs marginal B cells
Follicular: recirculating (majority)
Marginal: in spleen for blood-borne Ags
What causes B cells to undergo anergy
B cell recognizing Ag without BCR cross linking, co-stimulatory ligands, or cytokine support
What is critical for class switching and affinity maturation to occur?
CD40-CD40L interaction
Where do affinity maturation and class switching occur?
GCs
Class switching process: 2 steps
- Th and Tfh cell cytokines open switch regions in heavy chain DNA
- VDJ gene segment recombined with downstream C region gene
Affinity maturation
AID introduces point mutations in switch regions of variable and light Ig genes -> high affinity Abs
High affinity selection checkpoint after affinity maturation
FDCs provide Ags to new BCR receptor to sample -> if higher affinity, B cell clone is selected for further differentiation
Where are long lived plasma cells found?
Bone marrow (IgG), mucosa (IgA)
Plasma cells: what cell marker increases
CD27
Anti-apoptotic marker on memory B cells
Bcl-2
What cytokine signal is required to keep memory B cells alive?
IL-7
Antibody feedback
Excess Abs bound to a pathogen will block further Ab production
Microbe neutralization: classes and purpose
Done by all Ig classes, neutralizes the infectivity of a pathogen + block pathogens from binding cell surfaces to gain entry
Which Ig is a super efficient complement fixer?
IgM
Waste management function of Abs
Opsonization -> clearance of ICs from circulation in a non-inflammatory manner