中文摘要：

白细胞介素21（IL-21）是新近发现的一种细胞因子,主要由激活的CD4＋T细胞产生。IL-21通过其受体IL-21R发挥多种生物作用。IL-21R属于I型细胞因子受体家族,与IL-2、IL-4、IL-7、IL-9和IL-15受体共同享有γ链（γc）。许多研究表明IL-21独自或与其他细胞因子协同影响多种免疫细胞的增殖、生存、分化和功能,参与对免疫反应稳态平衡的调节。为了更全面了解IL-21研究进展,论文对IL-21与IR-21R的发现、结构特征、表达分布、信号通路以及IL-21对免疫细胞的调节作用进行综述。

英文摘要：

Interleukin-21（IL-21） is a novel cytokine discovered in 2000,which is mainly produced in activated CD4＋ T cells.IL-21 plays pleiotropic roles through its receptor（IL-21R） which is a novel type I cytokine receptor in conjunction with the common cytokine receptor γ chain（γc） of the IL-2,IL-4,IL-7,IL-9,and IL-15 receptors.The many research reports demonstrate that IL-21 is a novel immunomodulatory cytokine which influences the growth,survival,differentiation,and functions of various immune cells alone or in concert with other cytokines.In order to understand progress on IL-21,the discovery,structure,distribution,signal passage and.immunomodulation of IL-21 were introduced in this paper.