[The phenotype and function of CD4+ CD25+ regulatory T cells in hepatitis B patients].

OBJECTIVE

Our aim was to investigate the frequency, phenotype and function of CD4+ CD25 high regulatory T cells (Treg) in patients with acute and chronic hepatitis B (AHB, CHB).

METHODS

Peripheral blood mononuclear cells (PBMCs) from 16 AHB patients at acute phase (week 1 of illness), 72 CHB patients, and 32 health subjects were analyzed for Treg frequency and CD45RO, CD45RA, CD95 and HLA-DR phenotype by flow cytometry. Intracellular expression of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) was examined by intracellular cytokines staining. Forkhead/winged helix transcription factor (FoxP3) mRNA was detected by a real-time RT-PCR assay. The effects of MACS magnetic beads-purified Treg cells on the proliferation of PBMCs were examined by a [3H]-thymidine incorporation assay. The effect of Treg cells on IFN gamma secretion of autologous PBMCs was examined by ELISA.

RESULTS

CHB patients presented a higher fraction of circulating CD4+ CD25 high Treg frequency than AHB patients (P < 0.05), but had no significant difference compared with healthy controls. CD4+ CD25 high Treg expressed high levels of CD45RO, HLA-DR and CTLA-4, low level of CD45RA, and expressed FoxP3 mRNA specifically. We also observed that Treg cells could suppress the expansion and IFN gamma secretion of autologous PBMCs when stimulated with HBV antigen or anti-CD3 antibody, and the suppressive effect was stronger when HBV antigen was used as stimulator.

CONCLUSIONS

CHB patients presented a higher fraction of circulating Treg frequency than AHB patients at acute phase, but had no significant difference compared with healthy controls. FoxP3 mRNA was specifically expressed in CD4+ CD25+ cell population. Treg could suppress HBV antigen-specific T cell response in vitro. The study furthers our understanding of Treg's role in immunopathogenesis of hepatitis B.