Servicio de Inmunología, Unidad de Investigación, Hospital Universitario Puerta del Mar, 11009 Cádiz, Spain.
J Immunol. 2012 Feb 15;188(4):1578-81. doi: 10.4049/jimmunol.1102786. Epub 2012 Jan 16.
IL-21 induces the differentiation of activated B lymphocytes into plasma cells (PC), but its direct effect on PC remains uncertain. This study analyzes the role of IL-21 on human in vivo-generated PC. IL-21R was clearly expressed on PC from the human tonsil, the lymph node, and the spleen (secondary lymphoid organs [SLO]) but barely on terminally mature bone marrow PC. IL-21 enhanced Ig secretion by isolated SLO PC but not bone marrow PC. Tonsillar T follicular helper (Tfh) lymphocytes are known to secrete IL-21. Purified Tfh cells induced a marked increase of Ig production by tonsillar PC, and this effect was impaired when endogenous IL-21 production was blocked. IL-21 provoked a rapid and transient phosphorylation of STAT3 in tonsillar PC. Tfh cells or exogenous IL-21 reduce tonsillar PC apoptosis and increases PC recovery but does not modify their nonproliferating status. These results suggest that IL-21 derived from Tfh cells acts as a survival factor for SLO PC in vivo.
IL-21 诱导活化 B 淋巴细胞分化为浆细胞（PC），但其对 PC 的直接作用尚不确定。本研究分析了 IL-21 对体内生成的人 PC 的作用。IL-21R 在人扁桃体、淋巴结和脾脏（次级淋巴器官[SLO]）中的 PC 上明显表达，但在终末成熟的骨髓 PC 上几乎不表达。IL-21 增强了分离的 SLO PC 但不增强骨髓 PC 的 Ig 分泌。已知扁桃体滤泡辅助性 T（Tfh）淋巴细胞会分泌 IL-21。纯化的 Tfh 细胞诱导扁桃体 PC 产生明显增加的 Ig 产生，而当阻断内源性 IL-21 产生时，这种作用受损。IL-21 引起扁桃体 PC 中 STAT3 的快速和短暂磷酸化。Tfh 细胞或外源性 IL-21 减少扁桃体 PC 的凋亡并增加 PC 的恢复，但不改变其非增殖状态。这些结果表明，源自 Tfh 细胞的 IL-21 在体内作为 SLO PC 的存活因子发挥作用。
