Objective: To study the expression of CD70 and the methylation level of CD70 promoter in immuno-related pancytopenia（IRP）patients, and explore the role of CD70 in the pathogenesis of IRP.
Methods: Thirty- five IRP patients and fifteen healthy donors were enrolled in this study. Peripheral blood mononuclear cells were isolated from venous blood by density gradient centrifugation, and CD4(+) T cells were isolated by immunomagnetic beads. The mRNA level and the percentage of CD70 of CD4(+) T cells were measured by real- time quantitative polymerase chain reaction（RT- PCR）and flow cytometry respectively. Methylation- Specific PCR（MSP）was performed to determine the methylation level of CD70 promoter.
Results: The percentage of CD70 expression on CD4(+) T cells of untreated IRP patients［（7.46±1.51）%］was significantly higher than that of recovered ones［（5.95±1.34）%］and normal controls［（1.83 ± 0.60）%］, and that of recovered IRP patients was significantly higher than of normal controls（P<0.05）. The relative expressions of CD70 mRNA in CD4(+) T cells were 2.314（0.200-6.084）, 1.021（0.135-3.434）, 0.353（0.008-2.258）in three groups respectively. The differences among untreated IRP patients, recovered IRP patients and normal controls were significant（P<0.05）. The CD70 promoter methylation level in CD4(+) T cells of all IRP patients was significantly lower than that of normal controls （P<0.05）. The expression of CD70 positively correlated to the ratio of CD5(+) B cells（r=0.533, P<0.01）.
Conclusion: The overexpression of CD70 may lead to immunologic disarrangement of patients, which may play important role in the pathogenesis of IRP.
目的: 研究免疫相关性血细胞减少症(IRP)患者外周血CD4+ T淋巴细胞CD70 mRNA和蛋白的表达水平及CD70启动子甲基化水平，探讨CD70在IRP发病中的作用。
方法: 选取35例IRP患者(初治组16例，恢复组19例)及15名正常对照，应用密度梯度离心法分离其外周血单个核细胞，免疫磁珠分选CD4+ T淋巴细胞，应用实时定量PCR (RT-PCR)检测CD70 mRNA相对表达水平，采用流式细胞术检测CD4+CD70+/CD4+细胞比例，采用甲基化特异性PCR (MSP)法检测CD4+ T淋巴细胞CD70基因启动子区域甲基化水平。
结果: IRP患者外周血CD4+CD70+/CD4+细胞比例初治组[(7.46±1.51)%]高于恢复组[(5.95±1.34)%]和正常对照组[(1.83±0.60)%]，恢复组高于正常对照组(P值均<0.05)；IRP初治组、恢复组及正常对照组CD70 mRNA的表达水分别为2.314(0.200~6.084)、1.021(0.135~3.434)及0.353(0.008~2.258)，两两比较差异均有统计学意义(P<0.05)。IRP患者CD70启动子甲基化水平低于正常对照组(P<0.05)。IRP患者CD70表达率与CD5+ B淋巴细胞比例呈正相关(r=0.533，P<0.01)。
结论: CD4+ T淋巴细胞CD70启动子区域低甲基化水平导致CD70的过表达可引起其免疫紊乱，可能在IRP的发病中发挥重要作用。