滤泡树突状细胞与生发中心反应研究的新进展

生发中心是在T细胞依赖性抗体应答过程中于外周淋巴组织内形成的一个特殊的结构。在GC内,受抗原刺激而活化的B细胞进行克隆扩增、IgV区基因的体细胞高度突变、亲和力成熟以及同类型转换,最终形成记忆性B细胞或是产生Ig的浆细胞。在GC内B细胞增殖的同时,也启动了凋亡机制,以确保最终形成的记忆B细胞或浆细胞对抗原的高度特异性。FDCs是参与再次免疫应答的重要细胞,它主要是通过表面的FcR和CR将免疫复合物结合在细胞膜上,并选择性的将抗原递呈给表达高亲和力BCR的B细胞,使之激活并产生抗体或形成记忆B细胞。因此,FDCs在生发中心反应、免疫记忆的维持、B细胞的分化、成熟以及记忆B细胞的形成具有极其重要的作用。但最近的研究对FDCs及其结合的免疫复合物的重要性提出了质疑,认为FDCs在生发中心反应、B细胞的分化、成熟以及记忆B细胞的形成中的作用很可能是非特异性的,并对驻留在FDCs表面的免疫复合物的其它潜在功能进行了讨论。

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.