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 less than 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 less than 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.