centrocyters

Centrocyters is a term occasionally used to refer to B cells within germinal centers that have completed the rapid division and somatic hypermutation phase and are undergoing selection based on antigen affinity. In modern immunology, the more common term is centrocyte (plural centrocytes); the form centrocyter appears mainly in older literature or non-English sources and may be encountered as a synonym or misspelling.

In germinal centers, two zones are distinguished: a dark zone where centroblasts proliferate and mutate immunoglobulin genes, and a light zone where centrocytes reside and are subjected to selection. Centrocyters are typically smaller, less proliferative B cells located in the light zone. They express surface immunoglobulin bearing mutated variable regions and display MHC class II, enabling presentation of antigen-derived peptides to helper T cells. They also alter expression of surface and signaling molecules to facilitate interactions with follicular helper T cells.

Functionally, centrocyters test antigen affinity by presenting processed antigen to follicular helper T cells and receiving survival signals through CD40-CD40L interactions and cytokines. High-affinity clones are selected for continued survival and can differentiate into memory B cells or plasma cells; clones with low affinity generally die by apoptosis. Some centrocytes can re-enter the dark zone for additional rounds of mutation, contributing to ongoing affinity maturation.

Terminology and usage: The term centrocyter is not widely used in current literature; readers are encouraged to use centrocyte. The concept remains central to the germinal center reaction, a key process in adaptive immunity for producing high-affinity antibodies.