T1 L5, Adaptive immunity 2

Question 1

What are the 5 mechanisms for creating immune cell diversity?

Answer 1

• VDJ recombination
• Somatic hypermutation
• Affinity maturation
• Antibody class switching

Question 2

How does rearrangement in VDJ recombination occur?

Answer 2

It occurs on specific sites on the DNA called recombination signal sites (RSS’s)

It’s catalysed by 2 recombination activating genes: RAG-1 and RAG-2

3 steps: cleavage, repair/diversity, and joining

Question 3

What is somatic hypermutation?

Answer 3

It adds diversity to already VDJ recombined segments by inducing point mutations

Question 4

Which enzyme drives somatic hypermutation?

Answer 4

Activation-induced cytidine deaminase (AID)

Question 5

What is affinity maturation?

Answer 5

When B-cells produce antibodies with increased affinity for antigen. Only those with high affinity will be selected to survive

Question 6

What is class switch recombination?

Answer 6

Same receptor but a different constant region which changes the performance

Question 7

Why does alternative splicing result in IgM and IgD in all naive B-cells?

Answer 7

Because the genes are so close together that they occur together