Marinova Ekaterina, Han Shuhua, Zheng Biao
Department of Immunology, Baylor College of Medicine, Houston, TX 77030, USA.
J Immunol. 2007 Apr 15;178(8):5010-7. doi: 10.4049/jimmunol.178.8.5010.
Germinal center (GC) reaction is a T cell-dependent process in which activated B cells mature to produce high-affinity Abs and differentiate into memory B cells. The GC microenvironment is almost exclusively reserved for the optimal Ag-specific B cell clonal expansion, selection, and maturation, but lack significant conventional CD4(+) T cell responses. The mechanisms that ensure such a focused B cell response in the GC are not known. In this study, we report that human CD4(+)CD57(+) T cells, which are the major helper T cells in GCs, actively suppress the activation of conventional CD4(+) T cells, particularly Th1 cells, via a direct contact-dependent mechanism and soluble mediators. Our findings demonstrate that GC T cells are unique regulatory cells that provide critical help signals for B cell response but suppress conventional effector T cells in the same local environment.
生发中心（GC）反应是一个T细胞依赖的过程，在此过程中，活化的B细胞成熟以产生高亲和力抗体并分化为记忆B细胞。GC微环境几乎专门用于最佳的抗原特异性B细胞克隆扩增、选择和成熟，但缺乏显著的传统CD4(+) T细胞反应。确保GC中这种聚焦的B细胞反应的机制尚不清楚。在本研究中，我们报告称，人类CD4(+)CD57(+) T细胞是GC中的主要辅助性T细胞，它们通过直接接触依赖机制和可溶性介质，积极抑制传统CD4(+) T细胞，特别是Th1细胞的活化。我们的研究结果表明，GC T细胞是独特的调节性细胞，它们为B细胞反应提供关键的辅助信号，但在同一局部环境中抑制传统效应T细胞。
