Several investigators have reported a significantly reduced CD4/CD8 ratio, as defined by monoclonal antibodies, in the peripheral blood of Caucasian patients with chronic active hepatitis B (CAHB). In Asian patients with chronic hepatitis B, quantitative analyses of subpopulations of peripheral blood lymphocytes have not been able to confirm these findings. In this work, we analysed the frequency of peripheral blood lymphocyte subsets in 10 Chinese patients with histologically proven CAHB and seven healthy Chinese individuals. Four of the 10 CAHB patients received combined prednisolone/interferon-alpha2b (IFN-alpha2b) therapy. Peripheral blood samples were consecutively collected for analysis of lymphocyte subpopulations using an indirect immunofluorescence (IF) method, and hepatitis B virus (HBV) DNA was quantified by a chemiluminescent, molecular-hybridization assay. Peripheral blood mononuclear cells from seven Chinese control individuals comprised 63 +/- 3% CD3+ cells, of which 41 +/- 4% were of CD4+ and 23 +/- 2% of CD8+ subsets. The mean CD4/CD8 ratio in the healthy controls was 1.9 (95% confidence interval = 1.1-2.7). The CD4/CD8 ratios were significantly reduced (P < 0.01) in the 10 patients with chronic hepatitis B, compared with those of the controls, owing to a significant increase in the number of CD8+ cells (P < 0.005). During the treatment with prednisolone, a significant increase in the CD4/CD8 ratio was observed in all treated patients. This increase was mainly caused by a decrease in the number of CD8+ cells and was accompanied by an increase in serum HBV DNA levels, which peaked during the latter part of the prednisolone cycle. During the treatment with IFN-alpha2b, a second increase in the CD4/CD8 ratio was observed, which was caused by an increase in CD4+ cells. A marked decrease in viral load was observed, during treatment with IFN-alpha2b, in patients with HBV DNA levels below 10 000 pg ml-1. Our data indicate that the CD4/CD8 ratios in Chinese CAHB patients do not differ from those of Caucasian patients with CAHB, when analysed using similar methods for the enumeration of lymphocyte subsets. Profound effects on cellular distribution and viral replication were noted during the combined prednisolone/IFN-alpha2b therapy. Additional studies of the modulatory effect of the combined therapy on the distribution of lymphocyte subsets and cytokine profiles in relation to the therapeutic outcome of HBV infection are warranted.