中文摘要：

目的探讨转录因子FoxP3在外周血CD4^＋CD25^＋调节性T细胞（Treg）内的表达特性。方法取正常人外周血单个核细胞（PBMC），经固定／透膜处理进行细胞内染色，用流式细胞术（FCM）检测T细胞内FoxP3。以抗人CD3／CD28诱导T细胞活化，再用定量PCR及FCM术分别检测FoxP3 mRNA及蛋白质表达水平。结果FoxP3主要表达于CD4^＋T细胞，尤其是CD25高表达的CD4^＋T细胞，达97％左右；中等程度表达CD25的细胞中也含有少量FoxP3阳性细胞。T细胞活化后，表达FoxP3的CD4^＋CD25^＋T细胞比例显著增高，FCM检测结果与定量PCR结果一致。结论FoxP3不仅参与维持Treg细胞的功能，也与T细胞的活化有关。FCM检测细胞核内表达的FoxP3分子为研究Treg细胞提供了一种快速、简便的方法。

英文摘要：

Objective To investigate the expression of transcript factor FoxP3 in CD4^＋ CD25^＋ regulatory T cells from normal human peripheral blood. Methods The Intracelluar expression of FoxP3 in T cells was examined by flow cytometry through fixation/permeabilization and intracellular staining, and the expression of FoxP3 mRNA in activated T cells induced by anti-CD3/CD18 monoclonal antibodies was detected by real-time PCR. Results FoxP3 was mainly expressed in CD4^＋ T cells, especially in the CD4^＋ T cells with high level of CD25 expression, and the expression rate was about 97%. However, low level FoxP3 protein was also expressed in the CD4^＋ T cell with mediate CD25 expression . The significantly increased FoxP3 expression could be induced by the activation of T cells. The results of cytometry was consistent with the those from real-time PCR. Conclusion FoxP3 plays an important role not only in maintaining the function of regulatory T cell, also in the activation of conventional T cells. The analysis for FoxP3 by using flow cytometry provides an efficient tool in the further investigation on regulatory T cells.