Human follicular dendritic cells: function, origin and development

Follicular dendritic cells (FDCs) have important functions in the selection of memory B lymphocytes during germinal center reactions (GCR). They present native antigens to potential memory cells, of which only B cells with high affinity B cell receptors (BCR) can bind. These B lymphocytes survive, whereas nonbinding B cells undergo apoptotic cell death. FDCs are present in follicles of any secondary lymphoid organ and belong to the stromal cells of these organs. Ectopic FDC formation can be found in a number of autoimmune diseases and/or chronic inflammatory situations. This indicates that the development of FDCs is not restricted to secondary lymphoid organs, but that it is rather a matter of local conditions that drives a precursor cell type into FDC-maturation. A precursor of FDCs has presently not been identified, but phenotypic marker studies, in vitro experiments with fibroblast-like cell lines, and recent data on mesenchymal precursor cells from the peripheral blood suggest a close relation to fibroblast-like cells.