Humoral Immunity; Antibodies and the life cycle of B cells

Question 1

what does CDR mean

Answer 1

Complementarity Determining Regions

Question 2

4 main effector function of antigen binding to antibody

Answer 2

prevents pathogen-host binding
phagocytosis
lysis
NK-induced apoptosis

Question 3

different classes of antibody

Answer 3

IgG
IgD
IgA
IgM
IgE

Question 4

Heavy chain class switching

Answer 4

• Only affects heavy chain CONSTANT region
• Different effector functions — deal with different pathogens
• Minor: Differential splicing (mRNA level)
— lgM and lgD (last lecture)
• Major: DNA recombination
- lgM to lgG, lgA, lgE
- lgG to lgA, lgE

Question 5

Class switch recombination (CSR)

Answer 5

1) Cytokine signal;
2) Switch regions;
3) AID and DSB repair proteins
• Recombination between switch regions
• Switching only proceeds downstream
— lgM to lgG, lgA, lgE
— lgG to lgA, lgE

Question 6

during class switching which region changes

Answer 6

heavy chain constant region changes

Question 7

during class switching what cuts and forma the new one

Answer 7

AID + DSB repair proteins

Question 8

whats included in somatic recombination

Answer 8

V(D)J recombination
Tdt nucleotide addition
Somatic hypermutation
Class switching

Question 9

whats included in Differential splicinq

Answer 9

lgM and lgD
Membrane bound
and secreted lg

Question 10

is class switching reversible

Answer 10

NO

Question 11

One-turn/two-turn rule (12/23 rule)

Answer 11

Recombination only occurs between a segment with a 12bp spacer and a 23bp spacer

Question 12

Generation of antibody diversity

Answer 12

Multiple germline V, D and J gene segments
Combination V-J and V-D-J joining
Junctional flexibility
P-nucleotide addition
N-nucleotide addition
Combinatorial association of heavy and light chains
Somatic hypermutation during affinity maturation (next lecture)

Question 13

Allelic exclusion b cells

Answer 13

Two copies Of each lg gene — one from mother and one from father
In Other cells, both genes are expressed
Antibody genes different — Only one heavy chain allele and one light chain allele is expressed
Order of rearrangement: Heavy>kappa>lambda; 1st allele then 2nd
Ensure each B cell makes one type of antibody

Question 14

where does affinity maturation occur

Answer 14

in the germline centre

Question 15

B cell activation requires 3 signals

Answer 15

antigen binding to BCRs
co -stimulation by activated Th cell specific to same antigen
Th cell-derived cytokines

Question 16

name of the only t cell that can enter germinal centre

Answer 16

t follicular helper cells