Inhibition of CD4+ CD25+ regulatory T cells in chronic hepatitis B patients

Abstract

To evaluate the inhibition of CD4+ CD25+ regulatory T cells (Treg) in the chronic hepatitis B patients. Peripheral blood samples were collected from 22 patients with chronic hepatitis B (CHB) and 18 healthy blood donors to isolate the peripheral blood mononuclear cells (PBMCs). Flow cytometry was used to analyze the proportion of CD4+ CD127(lo)CD25(hi-int) Tregs in the CD4+ T cells so as to calculate the proportion of CD4+ CD25+ Tregs in the CD4+ T cells. BrdU incorporation method was used to evaluate the immune inhibition of the CD4+ CD25+ Tregs. CD4+ CD25- cells were isolated by magnetic bead sorting technique. The CD4- T cells and CD4+ CD25- T cells ere mixed and stimulated by HBVcore 18-27 peptide. The PBMCs of the CHB patients with the Treg depleted and Treg not depleted underwent detection of HBVcore18-27 specific cytotoxic T lymphocytes (CTLs). The IFN-gamma secretion of the CTLs in the PBMCs of CHB patients with Treg depleted and Treg not depleted was detected by HLA-pentamer and enzyme-linked immunospot assay (Elispot). The proportion of CD4+ CD127(lo)CD25(hi-int) Treg in the CD4+ T cells used to reflect the percentage of CD4+CD25+ Tregs in the CD4+ T cells of the CHB patients was 4.3% +/- 2.4%, significantly higher than that of the healthy controls (2.1% +/- 1.3%, t = 3.74, P <0.01). There was no significant difference in the inhibition of CD4+ CD25- T cells by autogenous CD4+ CD25+ T cells between the CHB patients and healthy controls. The frequency of CTLs induced by HBV core 18-27 of the CHB patients with their CD4+ CD25+ cells in circulation depleted was 0.74% +/- 0.31%, significantly higher than that of the patients whose CD4+ CD25+ cells in circulation were not depleted (0.17% +/- 0.08%, t = 4.75, P <0.01). The frequency of IFN-gamma secreting spots of HBVcore18-27-specific CD8+ T cells of the CHB patients with their CD4+ CD25+ cells depleted was (112 +/- 33), significantly higher than that of the CHB patients whose CD4+ CD25+ cells in circulation were not depleted [(23 +/- 14), t =7.828, P<0.01)]. The proportion of CD4+ CD25+ Treg in CHB patients is increased compared to the healthy blood donor. The proliferative capacity of CD4+ CD25- T cells is inhibited by the presence of CD4+ CD25+ Treg dose-dependently, and the inhibition of CD4+ CD25+ Tregs in the CHB patients is similar to the inhibition of CD4+ CD25+ Tregs in healthy donors. The elimination of Treg cells followed by stimulation with HBVcore18-27 peptide significantly improves the antivirus CTL responses in CHB patients.