中文摘要：

目的：探讨正常人外周血BCG特异性记忆T细胞的特征。方法：分离PPD^-和PPD^＋正常人PBMCs，与BCG进行培养，采用ELISA法检测细胞培养上清液中IFN-γ的水平，ELISPOT法检测分泌IFN-γ的细胞数，利用流式细胞仪在单个细胞水平上检测细胞表面分子及细胞内因子IFN-γ和IL-2的表达及其关系。结果：当BCG刺激后，PPD^＋正常人PBMCs不产生或只产生少量的IFN-γ，而PPD^＋者IFN-γ产生的量和细胞数均明显增加（P〈0．05）。流式细胞检测分析的结果表明，当BCG刺激后，主要是CD4^-而非CD8^＋T细胞表达IFN-γ和IL-2，两者相比具有显著差异。在CD4^＋T细胞中单独产生IFN-γ的细胞占大多数，其次为IFN-γ和IL-2双阳性细胞，只产生IL-2的细胞占少数。此外，85％～95％以上的CD4^＋IFN-γ^＋T细胞为CD45RO^＋，其中60％以上的细胞为CCR7^＋，其余的为CCR7^-。同样地，80％～95％左右的细胞为CD62L。。结论：BCG可以诱导抗原特异性记忆CD4^＋T细胞的产生，其中大多数为中央型记忆CD4^＋T细胞，少数为效应记忆CD4^＋T细胞，提示其在预防和控制结核分枝杆菌感染中发挥重要作用。

英文摘要：

Objective： To elucidate the characterization of antigen-specific memory T cells from PPD^＋ individuals after stimulation with BCG in vitro, Methods：PBMCs were isolated from PPD^-/＋ normal human peripheral blood and stimulated with BCG, The level of IFN-γin the culture supematants was assayed by ELISA and the frequency of IFN-γ-preducinging cells was detected by ELISPOT. The subsets and frequency of cytokine-producing cells were determined at a single cell level by flow cytometry, Results： After stimulation with BCG, PBMCs from PPD^＋ but not PPD - individuals produced significantly high levels of IFN-γ in culture supematants detected by ELISA（P 〈 0. 05 ）, similar results were confirmed with the ELISPOT detection. Flow cytometric analysis indicated that BCG could induce IFN-γand IL-2 production predominantly by CD4^＋T cells but not by CD8^＋T cells. Further analysis suggested that 85% -95% CD4^＋IFN-γ^＋ cells were memory cells in which more than 60% of cells were effector memory（CCR7^＋）T cells and the rest of them were central memory T cells（ CCR7^- ）, In addition, 80% -95% of the cells were CD62L^-. Conclusion： BCG could induce the generation of antigen-specific effector/memory CD4^＋ T cells and maintained in vivo.