What is the result of the process of somatic hypermutation?

Somatic hypermutation is a process that occurs in B cells after they encounter an antigen. This process introduces mutations at a high rate in the variable regions of immunoglobulin genes. The result is that B cells produce antibodies with varying affinities for the antigen. As these B cells proliferate, those that produce antibodies with higher affinity are preferentially selected for survival and expansion during the immune response.

The outcome of somatic hypermutation is a greater affinity of immunoglobulin molecules, particularly IgG, which are crucial for effective immune responses. By enhancing the affinity of antibodies to their specific antigens, somatic hypermutation leads to a more robust and effective defense by enabling the immune system to target pathogens more efficiently. This is vital in the development of a strong and lasting adaptive immune response.

In contrast, greater polymorphism of HLA class I or II is more related to the genetic diversity of the major histocompatibility complex (MHC) due to other mechanisms such as gene conversion or the diverse inheritance of MHC alleles, rather than somatic hypermutation. Similarly, inactivation of the T cell receptor does not relate to the process of somatic hypermutation, which specifically pertains to B cell function and antibody affinity maturation.