IL-2调节人外周血T淋巴细胞CTLA-4表达

IL-2 regulates CTLA-4 expression on human peripheral T cells

目的 探讨人外周血T淋巴细胞CTLA 4的表达情况及IL 2对其表达的调节作用。方法 采用流式细胞仪定量测定人外周血T淋巴细胞内及细胞膜上CTLA 4的水平 ,半定量RT PCR检测T淋巴细胞内CTLA 4mRNA的水平 ,并在体外用IL 2刺激T淋巴细胞后观察CTLA 4及CTLA 4mRNA水平的变化。结果 人外周血T淋巴细胞膜表面几乎不表达CTLA 4,7.6 %～ 18.0 %的T淋巴细胞有胞内表达 ,CD4+ T淋巴细胞表达CTLA 4的阳性比例略高于CD8+ T淋巴细胞 ;人T淋巴细胞可溶性形式的CTLA 4mRNA半衰期短于全长CTLA 4mRNA ;IL 2可以通过诱导人T淋巴细胞CTLA 4mRNA的转录上调CTLA 4的表达 ,IL 2诱导的细胞多为CD2 5 + T淋巴细胞。结论 CTLA 4多存在于人外周血T淋巴细胞内 ,参与T淋巴细胞活化过程的调节。IL 2的免疫抑制作用可能与其诱导T淋巴细胞内CTLA 4mRNA转录 ,从而上调CTLA 4的表达有关。

Objective To investigate the expression of CTLA-4 on human peripheral T cells and the regulatory effect of IL-2. Methods Before and after incubation of human PBMC with IL-2, both intracellular and surface expression of CTLA-4 in T cells were analyzed by Flow cytometry. Levels of CTLA-4 mRNA were determined by semiquantitative RT-PCR. Results There was no expression of CTLA-4 on the surface of human inactivated T cells. However, 7.6%-18.0% T cells expressed CTLA-4 intracellularly and the positive rate is some higher in CD4+ T cells than that in CD8+ T cells. The CTLA-4 del TM mRNA had a shorter half life than the full length CTLA-4 mRNA. The increased expression of CTLA-4 was dependent on the up-regulation of transcription of CTLA-4 mRNA in T cells induced by IL-2 and most of the T cells were CD25+. Conclusion CTLA-4 is mainly stored intracellularly to regulate the activation of human T cells. The immunosuppression effect of IL-2 may be correlated with the up-regulation of CTLA-4 expression on human T cell resulted from its stimulation on the transcription of CTLA-4 mRNA. [