The impact of CD4+CD25+ T cells in the tumor microenvironment of hepatocellular carcinoma

BackgroundHepatocellular carcinoma (HCC) is the most common liver cancer. Therapeutic results are usually unsatisfactory because liver tumors recur often. Immunologic factors may be related to the recurrence of HCC; however, this possibility is mentioned only rarely.MethodsThirty HCC patients undergoing hepatectomies were divided into 3 groups according to the diameters of their HCCs: group A (n = 8), diameter ≤3 cm; group B (n = 8), diameter >3 cm and ≤5 cm; and group C (n = 14), diameter >5 cm. T-lymphocytes from peripheral blood, nontumor liver tissue, and the HCC were analyzed.ResultsThe percentage of CD25+ in the CD4+ T cells did not differ between the peripheral blood and the nontumor liver tissue among the 3 groups. CD25+ cells were increased in the tumor tissue in group C patients (range, 6–41%; median, 22.9%; P = .003), compared to group A patients. The percentage of CD25+ in the CD4+ T cells in tumor tissue was positively correlated with tumor sizes (r = 0.556). These CD4+ CD25+ lymphocytes produced transforming growth factor-β and interferon-γ but not interleukin-10, and were anergic to plate-coated monoclonal antibodies (anti-CD3/anti-CD28). The characteristics of these antibodies were comparable to those of regulatory T cells. When the infiltration lymphocytes including CD4+ CD25+ T cells were added to the mixed lymphocyte reaction activated by autologous tumor lysate-pulsed dendritic cells, the proliferation of lymphocytes was inhibited.ConclusionThe increase of CD4+ CD25+ T cells in the tumor microenvironment correlates with tumor sizes. These CD4+ CD25+ regulatory T cells appeared to suppress the immune response activated by dendritic cells.