Generation of Antibody and TCR Diversity

Question 1

What is V(D)J recombination?

Answer 1

Random rearrangement of Variable (V), Diversity (D), and Joining (J) gene segments

Generates unique antigen receptors in B and T cells

Question 2

What is junctional diversity?

Answer 2

Random addition/removal of nucleotides during V(D)J joining

Mediated by enzyme TdT → increases variation

Question 3

What is somatic hypermutation?

Answer 3

Occurs in activated B cells in germinal centres

Introduces point mutations into V region to increase antibody affinity (affinity maturation)

Question 4

What is class switch recombination?

Answer 4

Switches antibody class (e.g. IgM → IgG/IgA/IgE)

Keeps the same antigen specificity but changes Fc region for different effector roles

Question 5

Do T cell receptors (TCRs) undergo somatic hypermutation or class switching?

Answer 5

No — TCRs only use V(D)J recombination

Once formed, TCR specificity is fixed

Question 6

How much diversity can these mechanisms generate?

Answer 6

Combined, these processes can generate millions of unique antigen receptors, enabling recognition of virtually any pathogen

Question 7

What should go in the introduction of an essay on receptor diversity?

Answer 7

Describe the need for vast receptor diversity from limited genetic material
Define adaptive immune flexibility

Question 8

What should the main body of the essay cover?

Answer 8

Genetic mechanisms: V(D)J recombination, junctional diversity
B-cell-specific features: somatic hypermutation, class switching
TCR generation: similarities and differences to BCRs

Question 9

What should the conclusion of the essay include?

Answer 9

Highlight how these processes underpin the adaptive immune system’s power
Mention clinical relevance (e.g. vaccines, immune memory)