Evolutionary and somatic selection of the antibody repertoire in the mouse.

The repertoire of antibody variable (V) regions has been subject to evolutionary selection, affecting both the diversity of V region genes in the germline and their expression in the B lymphocyte population and its subsets. In ontogeny, contact with an antigen leads to the expansion of B cells expressing antibodies complementary to it. In a defined phase of B cell differentiation, new sets of V regions are generated from the existing repertoire through somatic hypermutation. Cells carrying advantageous antibody mutants are selected into the memory compartment and produce a stable secondary response upon reexposure to the antigen.