Where do B cells undergo somatic hypermutation and affinity maturation?

Where do B cells undergo somatic hypermutation and affinity maturation?

• A. Thymic cortex
• B. Peyer's patches
• C. Germinal centers within lymphoid follicles
• D. Red bone marrow

Answer: (C)

Somatic hypermutation and affinity maturation occur in germinal centers within lymphoid follicles of secondary lymphoid organs. When B cells are activated by antigen, they migrate to these germinal centers, where the enzyme AID induces mutations in the variable regions of immunoglobulin genes. This generates a spectrum of B-cell receptors, and those with higher affinity for the antigen are selected with help from follicular dendritic cells and T follicular helper cells. The best-affinity B cells are then allowed to proliferate and differentiate into plasma cells or memory B cells. Thymic cortex is where T cells mature, red bone marrow is where B cells develop and undergo initial rearrangement, and Peyer’s patches are mucosal lymphoid tissue that can harbor germinal centers, but the process of somatic hypermutation and affinity maturation happens specifically in germinal centers.

Somatic hypermutation and affinity maturation occur in germinal centers within lymphoid follicles of secondary lymphoid organs. When B cells are activated by antigen, they migrate to these germinal centers, where the enzyme AID induces mutations in the variable regions of immunoglobulin genes. This generates a spectrum of B-cell receptors, and those with higher affinity for the antigen are selected with help from follicular dendritic cells and T follicular helper cells. The best-affinity B cells are then allowed to proliferate and differentiate into plasma cells or memory B cells. Thymic cortex is where T cells mature, red bone marrow is where B cells develop and undergo initial rearrangement, and Peyer’s patches are mucosal lymphoid tissue that can harbor germinal centers, but the process of somatic hypermutation and affinity maturation happens specifically in germinal centers.