Germinal Centres

AbstractGerminal centres are transient lymphoid structures appearing inside lymph follicles after an antigenic stimulation. They are closely associated with T‐dependent zones and oriented in the peripheral lymph organs in accordance with the entry of antigens. During this germinal centre reaction, B cells undergo not only clonal amplification but also affinity maturation and class switching of their immunoglobulins. These events, occurring under the control of T cells and in the peculiar environments created by the follicular dendritic cells, lead B cells to mature into B memory cells or into precursors of plasma cells. Most cells generated inside the germinal centres die by apoptosis and are eliminated by the tingible body macrophages. Peculiar genetic, infectious or proliferative pathological conditions can touch the germinal centres.Key Concepts:Germinal centres are polarised structures annexed to T‐dependent zones.Different cell populations exhibiting peculiar phenotypes compose the germinal centres.Chemotactism, proliferation, survival and maturation of B cells are guided by follicular dendritic cells and follicular T cells.Ig affinity maturation requires somatic hypermutations and stringent cell selection.The germinal centre reaction, induced by antigenic stimulation, involves sequential steps and is time‐limited.Particular genetic, proliferative or infectious diseases can alter the germinal cell functions.