中文摘要：

目的利用负载pp65495-503抗原肽的HLA-A＊0201四聚体染色结合流式细胞术,分析HLA-A2^＋健康青年供者外周血中HCMV pp65495-503特异性记忆CD8^＋T细胞的频率和表型。方法以优化的四聚体染色方法对22例中国青年供者全血进行染色,用流式细胞仪对样品进行三色荧光分析。结果健康中国青年人外周血中存在高频率的pp65495-503特异性CD8^＋T细胞,占CD8^＋T细胞的百分率为0.14-6.84%（均数2.45%）;表型分析显示其CD28^＋细胞占四聚体阳性和四聚体阴性细胞的百分率分别为为32.5%（±21.7%）和58.58%（±10.4%）（P〈0.001）;CD57^＋细胞占四聚体阳性和四聚体阴性细胞的百分率分别为55.8%（±18.4%）和27.4%（±8.3%）（P〈0.001）。同时,对三例健康青年人CD8^＋T细胞上多种表面分子的详细分析显示,pp65495-503特异性记忆CD8^＋T细胞有不同比率的细胞表达CD62L、CD45RO、CD38和CD27,而且还有一定比例的细胞表达CD45RA,但不表达活化抗原CD69分子。结论青年中国人外周血中存在高频率的HCMV特异性CD8^＋T细胞,这些细胞的表型存在高度异质性,可能是处于不同分化阶段的记忆和效应细胞群体组成。

英文摘要：

Objective To analyze the frequencies and phenotypes of CD8^＋T cells specific for human eytomegalovirus （HCMV） structural protein pp65-derived peptide （pp65495-503, NLV） in HLA-A2^＋young Chinese donors by using HLA-A2/NLV tetramer staining and flow cytometry.Methods Peripheral whole blood samples from 22 HLA-A2^＋donors were stained with HLA-A2/NLV tetramer and analyzed by tricolor flow cytometry.Results The frequencies of pp65495-503-specific CD8^＋T cells within total CD8^＋T cell population were between 0.14% and 6. 84 % （mean 2.45 % ） in the healthy young donors. The percentages of CD28^＋cells within tetramer-positive and -negative CD8^＋T cell populafious were （32.5%±1.7% ） and （58.58%±18.4% ）respectively, while CD57^＋ cells within these two cell pools were （55.8%±10.4% ） and （27.4%±8.3% ） respectively, with significant difference between the two groups （ P 〈 0.001 ）. Furthermore, the expression levels of other surface markers of three donors showed that different proportions of tetramer-positive CD8^＋T cells expressed CD62L, CD27, CD45RO, and CD38. In addition, a significant part of tetramer-positive CD8^＋T cells expressed CD45RA, whereas no significant CD69 expression was detected. Conclusion High frequencies of HCMV-specific CD8^＋T cells exist in the healthy young Chinese individuals. These cells are heterogeneous in phenotypes, suggesting that they may be composed of the memory and effector T cells at various differentiated stages.