肾移植后诱导活化高表达CD25的CD4~+ CD25~(high)调节性T细胞的表型特点与免疫调节功能

目的 探讨肾移植受者活化并表达不同强度CD25的CD4细胞的表型特征和功能特点.方法依据CD25的表达水平,应用流式细胞仪将9例行初次亲属活体肾移植受者的外周血CD4~+ T细胞分为CD25~-、CD25高表达(CD25~(high))和CD25低表达(CD25~(low))3群,并比较3群细胞叉头翼状螺旋转录因子(FoxP3)、细胞毒性T淋巴细胞相关抗原-4(CTLA-4)表达强度.经免疫磁珠法和CD4~+ CD25~+调节性T细胞分选试剂盒分选得到受者外周血CD4~+ CD25~-、CD4~+ CD25~(high) T细胞,分别作为反应细胞,以Co~(60)γ射线照射灭活的供者外周血单个核细胞(PBMC)作为刺激细胞,建立体外单向混合淋巴细胞培养系统.采用半定量RT-PCR检测系统中IL-2 mRNA的表达.结果 在肾移植术后受者3群细胞中,FoxP3的表达以CD4~+ CD25~(high)细胞最高(93.7%±3.58%),其次是CD4~+CD25~(high)细胞(16.4%±6.8%),CD4~+ CD25~-细胞最低(1.8%±1.1%),三者间差异均有统计学意义(P<0.01);CTLA-4表达以CD4~- CD25~(high)细胞最高(80.8%±7.9%),其次是CD4~- CD25~(low)细胞(22.9%±6.5%),CD4~- CD25~-细胞最低(4.1%±2.4%),三者间差异均有统计学意义(P<0.01).在混合淋巴细胞培养中,CD4~- CD25~(high)细胞受移植抗原刺激后不表达IL-2 mRNA;按照1:2比例加入CD4~- CD25~(high)细胞后,CD4~-细胞表达的IL-2 mRNA平均被抑制了60%.结论 肾移植受者所有活化T细胞的表面均有CD25表达,高表达CD25的细胞群具有调节性T细胞的表型特点,为CD4~+ CD25~(high)曲调节性T细胞.

Phenotypic profile and immunoregulation function of CD4~+ T cells which activate and highly expresses CD25 after renal transplantation

Objective To study the phenotypic profile and immunoregulation function of CD4~+ T cells which activate and expresses different levels of CD25 in the recipients of renal transplantation. Methods The representative phenotypic profile of CTLA-4 and FoxP3 from gated CD4~+ CD25~(high), CD4~+ CD25~(low) and CD4~+ CD25~- T cell subsets was analyzed.PBMC-Treg (depletion of Treg) and PBMC-Treg +Treg(at a ratio of 2:1) were used as effector cells with irradiated PBMCs from donors to create mixed lymphocyte cultures.Semiquantitative PCR analysis of mRNA was performed to determine the relative levels of IL-2 message.Results FoxP3,which can be associated with a unique marker of the Treg, was expressed at significantly higher levels by the CD4~+ CD25~(high) population (93.7%±3.58%)than by CD4~+ CD25~(low)(16.4%±6.8%)or CD4~+ CD25~-(1.8%±1.1%)subset.The intracellular CTLA-4 was expressed by only 4.1%±2.4%of CD4~+ CD25~-cells,by 22.9%±6.5%of the CD4~+ CD25~(low) cell subset,and by 80.8%±7.9%of the CD4~+ CD25~(high)cells.The expression of IL-2 mRNA were significantly inhibited in the co-cultures by CD4~+ CD25~(high) cells,60% suppression occurred at the 1:2 cell ratios (CD4~+ CD25~(high) regulatory cells to CD4~+ CD25~- responder cells) respectively.Conclusions CD25 may express on the surface of all the activated T cells after transplantation. CD25~(high) population exhibits the phenotypic profile of regulatory T cells,and is CD4~+ CD25~(high) regulatory T cell.