Research progress on follicular dendritic cells and germinal-centre reaction

Germinal-centre is a special structure formed in peripheral lymphoid tissues during T-cell-dependent humoral responses.In Germinal-centre,antigen-activated B cells recruited into germinal centers undergo a complex cellular program that allows for extensive expansion,isotype switching,somatic hypermutation,and differentiation into antibody-forming cells and memory cells.Another event proposed to occur in the germinal centre reaction is that high affinity variants are preferentially selected while low affinity or self-reactive clones are eliminated by B cell receptor (BCR)-mediated apoptosis for insuring the antibody-forming cells and memory cells' high specially to antigens.Follicular dendritic cells (FDCs) are the stromal cells located in the germinal centre.Although the capacity of FDCs to present antigen to B cells through antigen-antibody complexes has been recognized for many years,additional critical functions of FDCs have only recently been recognized.But,many recent studies question the importance of FDCs and their bound immune complexes in B-cell responses.They argue that the retention of immune complexes is not required for germinal centre development,affinity maturation and memory B-cell maintenance.Instead,it is probable that FDCs support B-cell proliferation and differentiation in a nonspecific manner.Other potential roles of immune complexes retained by FDCs are discussed.