原发性肝细胞癌患者CD4^＋CD25^＋调节性T淋巴细胞的频率、表型及功能

The frequency, phenotypes and functions of CD4^＋ CD25^＋ regulatory T cells in hepatocellular carcinoma patients

目的探讨CD4^＋CD25^＋调节性T淋巴细胞（CD4^＋CD25^＋Treg）在HCC患者外周血及肿瘤组织中的频率、抑制功能及临床意义。方法收集18例原发性HCC患者的PBMC、肝癌组织及相应的癌旁组织标本,以及10例CHB患者和15名健康对照的外周血标本,以三色与四色流式分析法分析PBMC以及肿瘤浸润的淋巴细胞中CD4^＋CD25^＋Treg的频率及表型,并同时分析其与HBV持续感染、肿瘤TNM分期和其他临床指标的关系,用BrdU掺入法评价CD4^＋CD25^＋Treg的免疫抑制功能。结果与健康对照组相比HCC患者、慢性HBV感染者外周血中CD4^＋CD25^＋Treg频率明显上升（P＜0．01）,且HCC患者肿瘤浸润的淋巴细胞中CD4^＋CD25^＋Treg的频率也明显上调（P＜0．01）;随着肿瘤的进展HCC患者外周血中CD4^＋CD25^＋Treg呈上升趋势（P＜0．05）; HCC患者CD4^＋CD25^＋Treg可非特异性地抑制自身活化的CD4^＋CD25^- T淋巴细胞,并呈剂量依赖性,且抑制能力与健康对照组相比差异无统计学意义。结论HCC患者外周血中及肿瘤组织中CD4^＋CD25^＋Treg的频率升高,增多的CD4^＋CD25^＋Treg可能参与抑制抗HCC的免疫应答,从而使肝癌细胞逃脱机体的“免疫监视”作用。

Objectives （1） To evaluate the prevalence, phenotypes and suppressive function of CD4^＋CD25^＋ regulatory T cells （Tregs） among the in peripheral blood mononuclear cells （PBMCs） and tumor- infiltration lymphocytes （TILs） from hepatocellular carcinoma （HCC） patients and patients with chronic hepatitis B. （2） To investigate the correlation between the frequency of CD4^＋CD25^＋ Tregs and clinical characteristics of HCC patients. Methods PBMCs and TILs in 18 HCC patients, 10 chronic hepatitis B （CHB） patients and 15 healthy donors were evaluated for the phenotypes of CD4^＋CD25^＋ Tregs and the proportion of CD4^＋CD25^＋ Tregs as a percentage of the total CD4^＋ cells, by flow cytometric analysis with three or four color staining. The relationship between the frequency of CD4^＋CD25^＋ Tregs and tumor TNM stages was analyzed. The CD4^＋CD25^＋ Tregs and CD4^＋CD25^＋ T cells were isolated from PBMC of HCC patients and donors. The suppressive function of CD4^＋CD25^＋ Tregs was analyzed. Results The percentages of CD4^＋CD25^＋ Tregs of the HCC patients （6.38% ± 6.30%） and CHB patients （4.29% ± 1.82%） were significantly higher than those of the healthy donors （1.58% ± 0.55%, P 〈 0.01）. Among the TILs, the percentage of CD4^＋CD25^＋ Tregs was higher （t = 4.39, P 〈 0.01）. There were significant differences in the prevalence of CD4^＋CD25^＋ Tregs in early and advanced stage HCCs （stage Ⅱ vs. Ⅲ, P 〈0.05; stage Ⅱ vs. Ⅳ P 〈0.01）. The proliferative capacity of CD4^＋CD25^＋ T cells was inhibited by the presence of CD4^＋CD25^＋ T cells in a dose-dependent manner where the level of suppression was correlated to the ratio of the two-cell populations. Conclusion These results suggest that the increase in frequency of CD4^＋CD25^＋ Tregs might play a role in the suppression of the immune response against HCC, which may contribute to the HCC cells that escaped from immunological surveillance.