Plasma cell differentiation during the germinal center reaction.

Germinal centers (GCs) are formed in secondary lymphoid tissues upon immunization with T-dependent antigens. In GCs, somatic hypermutation generates B cells with increased antibody affinity and these high-affinity B cells preferentially differentiate into plasma cells, which home to bone marrow and confer long-lived humoral immunity. Recent studies have shed new light on the cellular and molecular basis for initiating the transition from a GC B cell to a plasma cell. Here, we review recent progress in our understanding of how plasma cell generation during the GC reaction is regulated for inducing effective long-term protective immunity and for preventing harmful autoimmunity.