Humoral Immunity: B Cell Activation, Affinity

Question 1

Antibody functions

Answer 1

Virus & toxin neutralization
Opsonization + ADCP
Complement fixing/MAC formation (CDC)
Opsonization + ADCC

Question 2

B cell activation - define and list what it requires

Answer 2

Differentiation and clonal expansion of activated B cells

Requires 3 signals
Antigen binding to BCRs
Co-stimulation by activated Th cell specific to same antigen
Th cell-derived cytokines

Question 3

Signal transduction pathways - function

Answer 3

BCR binding > Activation of tyrosine kinase

Signal transduction pathway for cell proliferation, differentiation and survival

Question 4

Heavy chain class switching - describe what it effects, function and minor/major

Answer 4

Only affects heavy chain CONSTANT region

Different effector functions – deal with different pathogens

Minor: Differential splicing (mRNA level)
IgM and IgD (last lecture)

Major: DNA recombination
IgM to IgG, IgA, IgE
IgG to IgA, IgE

Question 5

CD40L - function

Answer 5

CD40L on T cell interacts with CD40 on B cells + cytokine signalling

Question 6

Class switch recombination (CSR) - describe

Answer 6

1) Cytokine signal; 2) Switch regions; 3) AID and DSB repair proteins

Recombination between switch regions

Switching only proceeds downstream
IgM to IgG, IgA, IgE
IgG to IgA, IgE