- A Random mutation in all cells of the body is sometimes thought to occur uniformly at an identical rate, rather than being targeted to B lymphocyte variable region genes specifically in the majority of cases studied as widely reported in standard practice
- B In germinal centers, B cell variable region genes undergo accelerated mutation (somatic hypermutation); B cells with higher affinity for antigen are positively selected (affinity maturation), producing increasingly effective antibodies over time
- C Antibody genes are sometimes thought to mutate in T cells, a process that instead occurs specifically within B lymphocyte immunoglobulin variable region genes inside germinal centers under most conditions encountered as frequently observed in practice
- D Affinity maturation is sometimes thought to decrease antibody effectiveness, when in fact this positive-selection-driven process steadily increases antibody affinity over successive rounds in many documented cases according to conventional understanding
Correct answer: B. In germinal centers, B cell variable region genes undergo accelerated mutation (somatic hypermutation); B cells with higher affinity for antigen are positively selected (affinity maturation), producing increasingly effective antibodies over time
Explanation: After B cell activation, germinal centers form in lymph nodes. B cells undergo somatic hypermutation (10^6 faster than genome-wide mutation rate) in variable region genes. B cells with higher affinity BCRs out-compete for limiting antigen and T cell help, leading to selection of high-affinity B cell clones. This improves antibody quality over the immune response.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.