CD4^+CD25^+T_(reg)细胞调节T细胞的作用机制分析

Immunological mechanism of regulatory T cells acting on effector T cells

目的 通过检测Treg细胞表达介导抑制性共刺激分子CTLA4和分泌抑制性细胞因子,并设置Treg细胞与效应性T细胞共培养和分隔培养实验模型,分析Treg细胞对效应性T细胞形成抑制作用的可能机制及各机制的主次要关系。方法对比分析Treg细胞与效应性T细胞膜分子CTLAA4、CD28表达和细胞因子IL-10、TGF-β1分泌水平;以TransWell Milli-cell-PCF分隔培养槽分隔培养Treg细胞与不同淋巴细胞组成的反应体系,采用向共培养及分隔培养体系加入与不加入IL-10、TGF-β1抗体的阻断方法,检测Treg细胞对不同组混合淋巴细胞反应的抑制效率。结果 Treg细胞分泌IL-10和TGF-β1的浓度水平明显高于效应性T细胞,Treg细胞培养上清中IL-10和TGF-β1水平分别达到(380±36.3)pg/ml和(790±56.8)pg/ml,Treg细胞分泌IL-10和TGF-β1的浓度水平与效应性T细胞比较,均有显著性差异(P<0.01)。共刺激分子CTLA4、CD28在Treg细胞和效应性T细胞膜表面的表达水平存在明显差异,Treg细胞以表达CTLA4为主。Treg细胞对共培养体系混合淋巴细胞反应的抑制效率明显高于分隔培养,通过分泌IL-10对效应性T细胞的抑制作用亦明显强于通过TGF-β1。结论细胞接触机制是Treg细胞抑制效应性T细胞的主要作用机制,而细胞因子机制中。

Objective To detect the inhibitory co-stimulating cytologic T-lymphocyte-associated antigen 4 (CT-LA4) and cytokines secreted by regulatory T (Treg) cells, and to explore the immunological mechanism of Treg cells acting on effector T cells in co-cultured system(CCS) and separate-cultured system(SCS) . Methods The percentages of CTLA4 and CD28 expressed on the Treg cells and effector T cells were determined. Treg cells were added to mixed lymphocyte reaction (MLR) system in CCS and Trans Well Millicell-PCF SCS. The inhibitory effects of Treg cells on the MLR were detected after adding or not adding anti-IL-10 or TGF-B1 to the reacting systems. Results Compared with effector T cells, Treg cells expressed higher level of CTLA4 and secreted higher levels of IL-10 and TGF-B1 ( P < 0.01) . The inhibitory effect of Treg cells co-cultured with effector T cells was much stronger than that in separate cultured group (P < 0.01). Moreover, the inhibition rate of Treg cells on effector T cells through the secretion of IL-10 was higher than that through the secretion of TGF-B1 ( P < 0.01) . Conclusion Both cell-to-cell contact and cytokine secretion mechanisms are involved in the regulation of T cells by CD4+ CD25+ Treg cells. Cytokines have stronger inhibitory effect on effector T cells by means of secretion of IL-10.