[The characterization of regulatory T cells in peripheral blood of HBV-infected patients].

Objective: CD4(+)CD25(high) regulatory T cells (Treg) have been shown to play an important role in maintaining peripheral tolerance against self and foreign antigens, and in suppressing T cell immune response. Our aim was to characterize circulating Treg in HBV-infected patients.

Methods: Treg in peripheral blood from 72 chronic hepatitis B (CHB) patients, 16 acute hepatitis B (AHB) patients and 32 healthy subjects were quantitatively analyzed using flow cytometry. Serum HBV markers were evaluated for each subject. HBV-DNA levels were measured using real-time RT-PCR.

Results: CHB patients presented a higher fraction of circulating Treg (3.9% +/- 1.4%) than those in AHB patients (3.1% +/- 0.9%) (P < 0.05), but were similar to healthy controls (3.5% +/- 0.7%). CHB patients with greater than 10(7) copies/ml of serum HBV DNA loads had a higher frequency (4.5% +/- 1.9%) of circulating Treg than health controls (P < 0.01) and the patients with less than 10(7) copies/ml of serum viral loads (3.4% +/- 0.7%). A correlation was found between circulating Treg and HBV DNA level (r = 0.32, P < 0.01). Furthermore, Treg was more frequent in convalescent phase (6.0% +/- 1.7%) than in early acute phase (3.0% +/- 0.6%).

Conclusion: Increased peripheral Treg is found to be associated with HBV replication in chronic hepatitis B. In acute HBV infection, Treg is less frequent in early phase. The related mechanisms is under further investigation.