中文摘要：

目的了解脐带血T细胞及其CD4＋和CD8＋T细胞亚群的信号传导分子CD3ζ基因的表达特点。方法采用SYBRGreenI荧光定量PCR和相对定量分析法检测60例脐带血单个核细胞和12例纯化脐带血CD4＋及CD8＋T细胞的CD3；基因的表达情况，以胆微球蛋白基因（β2M）作为内参，采用相对定量公式：2-△Ct×100％，计算CD3ζ基因相对mRNA表达量，60例健康成人作为对照。并根据荧光定量PCR熔解曲线特点和序列分析了解CD3ζ基因突变情况。结果全部脐带血和健康成人外周血单个核细胞均表达CD3ζ基因，不同个体CD3ζ基因表达量有所差异，脐带血T细胞CD3ζ基因相对mRNA表达量为6．7％±5．56％，CD4＋和CD8＋T细胞的CD3ζ基因相对mRNA表达量分别为6．74％±2．0％和6．88％±1．76％，三者CD3ζ基因表达量均明显高于健康成人（P=0．000，P=0．034，P=0．000）。序列分析结果显示尚未发现国外文献所报道的ζ链剪接异构体。结论本研究率先报道了脐带血T细胞及其CD4＋和CD8＋T细胞亚群的CD3ζ基因mRNA的表达水平，为进一步了解脐带血T细胞免疫学特点提供新的基础资料。

英文摘要：

Objective To investigate the expression level of signaling transduction factor CD3ζ gene in mononuclear cells, and CD4＋ and CD8＋ T cells from umbilical cord blood. Methods Real-time PCR with SYBR Green I technique was used for detecting CD3ζ gene expressionlevel in 60 cases of mononuclear cells and 12 cases of sorted CD4＋ and CD8＋ T cells from umbilical cord blood, with β2- microglobulin gene （β2M） as an endogenous reference. Relative mRNA expression level of CD3ζ gene was analyzed by the formula of 2-△Cr × 100%. The mutation or polymorpheirm of CD3ζ gene was determined on the basis of different melting temperature and nucleotide sequencing. The peripheral blood of 60 healthy adults served as controls. Results CD3ζ gene was expressed in all cases from both umbilical cord blood and healthy adults. There was the diversity of CD3ζ gene expression levels in different individuals. The mean value （6.7% ± 5.56% ） of relative mRNA expression level of CD3ζ gene was found in 60 cases of umbilical cord blood; the mean value （6.74 % ± 2.0 % and 6.88 % ± 1.76 % ） were detected in CD4＋ and CD8＋ T cells from umbilical cord blood, respectively. The relative mRNA expression levels of CD3ζ gene in mononuclear cells, CD4＋ and CD8＋ T cells from umbilical cord blood were significantly higher than those of healthy adults （ P = 0.000, P = 0. 034, P = 0.000）. Sequence analysis indicated no mutation or polymorpherim of CD3ζ gene from all detected samples. Conclusion This is the first report of CD3ζ gene expression in mononuclear cells, CD4＋ and CD8＋ T cells from umbilical cord blood, which might provide new data for farther understanding the feature of T cell immune state in umbilical cord blood.