5. Adaptive Immunity 2

Question 1

What is VDJ recombination?

Answer 1

Genetic recombination of a variable region with a
diversity region and a joining region

-Occurs in both B-cells and T-cells

Question 2

What are the key enzymes involved in VDJ recombination?

Answer 2

Recombination-activating genes

RAG-1 and RAG-2

Question 3

What is somatic hypermutation?

Answer 3

refinement of B-cell receptor recognition of antigen

changes affinity of antibody

Question 4

Expression of IgM and igD

Answer 4

The expression is not by CSR as the naïve B-cell has not yet experienced antigen

IgM and IgD are produced by alternative mRNA splicing due to the close proximity of the mu and delta constant regions

Question 5

Class switch recombination

Answer 5

-Last step in a B-cell’s
response to antigen.

• The class switching does not affect the affinity of the B-cell receptor for antigen

-Replaces the constant region of the antibody so
that it can interact with different effector molecules.

• only affects heavy chain
• Mediated by a process of DNA breakage and recombination

Question 6

What is the name of the key enzyme in SHH?

Answer 6

Activation-induced cytidine deaminase (AID)

Question 7

What region of the antibody does SHM occur in

Answer 7

variable region so affects both HC and LC

Question 8

What region of the antibody does CSR occur in

Answer 8

constant region so only HC