FOLLICULAR DENDRITIC CELLS AND APOPTOSIS - LIFE AND DEATH IN THE GERMINAL CENTER

The germinal centre forms a specialized microenvironment thought to pl ay a key role in the induction of antibody synthesis, affinity maturat ion of B cells and memory B cell formation. Clonal-expanded follicular B lymphocytes with mutated antigen receptors (centrocytes) have to be selected on the basis of their capacity to compete for binding to ant igen held in limited amounts on the follicular dendritic cells. In thi s way, only high-affinity B cells are selected. Binding to a follicula r dendritic cell is an unconditional prerequisite for centrocytes to s urvive, Cells that do not succeed in binding to a follicular dendritic cell die rapidly by apoptosis. Apoptosis is a common form of cell dea th characterized by the activation of an endonuclease culminating in n uclear destruction. The pathway by which apoptosis is triggered varies from cell type to cell type. However, for germinal centre B cells thi s process is still poorly understood.