T cell help for antibody production is a fundamental aspect of immune responses. Only recently has a better understanding of the cellular and molecular mechanisms for T cell help emerged. A subset of T cells, termed T follicular helper cells (T(FH) cells), provides a helper function to B cells and represents one of the most numerous and important subsets of effector T cells in lymphoid tissues. T(FH) cells are distinguishable from Th1 and Th2 cells by several criteria, including chemokine receptor expression (CXCR5), location/migration (B cell follicles), and function (B cell help). Central to the function of CD4(+) T cells is IL-21, a "helper" cytokine produced by T(FH) cells that potently stimulates the differentiation of B cells into Ab-forming cells through IL-21R. Consequently, dysregulation of T(FH) cell function, and over- or under-expression of T(FH) cell-associated molecules such as ICOS or IL-21, most likely contributes to the pathogenesis of certain autoimmune diseases or immunodeficiencies.

中文翻译：

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正常和异常免疫应答中的T卵泡辅助细胞（TFH）。

T细胞帮助产生抗体是免疫反应的基本方面。直到最近才对T细胞帮助的细胞和分子机制有了更好的了解。T细胞的一个子集，称为T卵泡辅助细胞（T（FH）细胞），为B细胞提供辅助功能，代表淋巴组织中效应T细胞中数量最多，最重要的子集之一。T（FH）细胞可通过几种标准与Th1和Th2细胞区分开，包括趋化因子受体表达（CXCR5），位置/迁移（B细胞卵泡）和功能（B细胞帮助）。CD-21 +是CD4（+）T细胞功能的核心，IL-21是由T（FH）细胞产生的“辅助”细胞因子，可有效刺激B细胞通过IL-21R分化为形成Ab的细胞。因此，T（FH）细胞功能失调，