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目的初步探讨IL-15诱导CD4+CD25-T细胞向CD4+CD25+调节性T细胞(Tregs)转化的机制。方法采用免疫磁性细胞分离法分离人外周血中的CD4+CD25-T细胞,依据加入细胞因子不同分为4组:对照组、IL-15组、拮抗1组、拮抗2组,其中后3组均于培养的第1天加入IL-15,而拮抗1组和拮抗2组分别于培养第1、3天加入STAT5a封闭性肽。流式细胞仪检测细胞表型变化,3H-TdR掺入法检测IL-15诱导产生的Tregs抑制CD4+CD25-效应T细胞(Teff)增殖的免疫功能,Western blot法检测细胞内p-STAT5的变化。结果与对照组比较,IL-15能诱导CD4+CD25-T细胞中CD25和Foxp3表达上调,IL-15诱导生成的Tregs具有较天然Tregs稍弱的免疫抑制功能。Western blot检测结果显示,IL-15组p-STAT5表达较对照组明显上调。加入STAT5a封闭性肽后,拮抗1组和拮抗2组中CD4+CD25-T细胞中CD25和Foxp3表达下调,但拮抗2组[细胞表型分别为(47.9±6.0)%、(20.7±3.4)%]改变较拮抗1组[细胞表型分别为(30.7±8.5)%、(9.2±2.2)%]改变轻微。结论IL-15能诱导CD4+CD25-T细胞向Tregs转化,其机制可能是上调p-STAT5的表达。
Objective To investigate the mechanism of IL-15-induced CD4 + CD25-T cell transformation into CD4 + CD25 + regulatory T cells (Tregs). Methods CD4 + CD25-T cells in human peripheral blood were isolated by immunomagnetic separation and divided into 4 groups according to the different cytokines: control group, IL-15 group, antagonistic group 1 and antagonistic group 2, among which the latter 3 groups IL-15 was added on the first day of culture while the antagonist 1 and antagonist 2 groups were respectively added with STAT5a-blocking peptide on day 1 and 3 of culture. Flow cytometry was used to detect the phenotypic changes. Tregs induced by IL-15 were detected by 3H-TdR incorporation. The immune function of CD4 + CD25- T cells was detected by Western blot. The expression of p-STAT5 Variety. Results Compared with the control group, IL-15 induced up-regulation of CD25 and Foxp3 expression in CD4 + CD25-T cells. Tregs induced by IL-15 had weaker immunosuppressive effects than Tregs. Western blot results showed that the expression of p-STAT5 in IL-15 group was significantly higher than that in control group. After adding STAT5a blocking peptide, the expression of CD25 and Foxp3 in CD4 + CD25-T cells in both antagonistic and antagonistic 2 groups was down-regulated, but antagonistic in 2 groups [cell phenotype was (47.9 ± 6.0)% and (20.7 ± 3.4) %] Compared with the antagonistic group 1 [cell phenotype (30.7 ± 8.5)%, (9.2 ± 2.2)%] slight change. Conclusion IL-15 can induce the transformation of CD4 + CD25-T cells to Tregs, and its mechanism may be up-regulated the expression of p-STAT5.