AIM: To characterize the peripheral T-cell subpopulation profiles and their correlation with hepatitis B virus (HBV) replication in different clinical stages of chronic HBV infection.METHODS: A total of 422 patients with chronic HBV infection were enrolled in this study. The patients were divided into three stages: immune-tolerant stage, immune active stage, and immune-inactive carrier stage. Composition of peripheral T-cell subpopulations was determined by flow cytometry. HBV markers were detected by enzyme-linked immunosorbent assay. SerumHBV DNA load was assessed by quantitative real-time polymerase chain reaction.RESULTS: CD8+ T-cells were significantly higher in patients at the immune-tolerant stage than in patients at the immune-active and -inactive carrier stages (36.87 ± 7.58 vs 34.37 ± 9.07, 36.87 ± 7.58 vs 28.09 ± 5.64, P < 0.001). The peripheral blood in patients at the immune-tolerant and immune active stages contained more CD8+ T-cells than CD4+ T-cells (36.87 ± 7.58 vs 30.23 ± 6.35, 34.37 ± 9.07 vs 30.92 ± 7.40, P < 0.01), whereas the peripheral blood in patients at the immune-inactive carrier stage and in normal controls contained less CD8+ T-cells than CD4+ T-cells (28.09 ± 5.64 vs 36.85 ± 6.06, 24.02 ± 4.35 vs 38.94 ± 3.39, P < 0.01). ANOVA linear trend test showed that CD8+ T-cells were signif icantly increased in patients with a high viral load (39.41 ± 7.36, 33.83 ± 7.50, 31.81 ± 5.95 and 26.89 ± 5.71, P < 0.001), while CD4+ T-cells were signif icantly increased in patients with a low HBV DNA load (37.45 ± 6.14, 33.33 ± 5.61, 31.58 ± 6.99 and 27.56 ± 5.49, P < 0.001). Multiple regression analysis displayed that log copies of HBV DNA still maintained its highly signif icant coefficients for T-cell subpopulations, and was the strongest predictors for variations in CD3+, CD4+ and CD8+ cells and CD4+/CD8+ ratio after adjustment for age at HBV-infection, maternal HBV-infection status, presence of hepatitis B e antigen and HBV mutation.CONCLUSION: Differences in peripheral T-cell subpopulation profi les can be found in different clinical stages of chronic HBV infection. T-cell impairment is signifi cantly associated with HBV load. AIM: To characterize the peripheral T-cell subpopulation profiles and their correlation with hepatitis B virus (HBV) replication in different clinical stages of chronic HBV infection. METHODS: A total of 422 patients with chronic HBV infection were enrolled in this study. The patients were divided into three stages: immune-tolerant stage, immune active stage, and immune-inactive carrier stage. Composition of peripheral T-cell subpopulations was determined by flow cytometry. HBV markers were detected by enzyme-linked immunosorbent assay. assessed by quantitative real-time polymerase chain reaction .RESULTS: CD8 + T-cells were significantly higher in patients at the immune-tolerant stage than in patients at the immune-active and -inactive carrier stages (36.87 ± 7.58 vs 34.37 ± 9.07, 36.87 ± 7.58 vs 28.09 ± 5.64, P <0.001). The peripheral blood in patients at the immune-tolerant and immune active patients contained more CD8 + T-cells than CD4 + T-cells (36.87 ± 7.58 while peripheral blood in patients at the immune-inactive carrier stage and in normal controls contained less CD8 + T-cells than CD4 + T-cells (28.09 ± 5.64 vs 30.23 ± 6.35, 34.37 ± 9.07 vs 30.92 ± 7.40, P <0.01) vs 36.85 ± 6.06, 24.02 ± 4.35 vs 38.94 ± 3.39, P <0.01). ANOVA linear trend test showed that CD8 + T-cells were signif icly increased in patients with a high viral load (39.41 ± 7.36, 33.83 ± 7.50, 31.81 ± 5.95 and 26.89 ± 5.71, P <0.001) while while CD4 + T-cells were signif ically increased in patients with a low HBV DNA load (37.45 ± 6.14, 33.33 ± 5.61, 31.58 ± 6.99 and 27.56 ± 5.49, P <0.001). Multiple regression analysis displayed that log copies of HBV DNA still maintained its highly signif icant coefficients for T-cell subpopulations, and was the strongest predictors for variations in CD3 +, CD4 + and CD8 + cells and CD4 + / CD8 + ratio after adjustment for age at HBV-infection , maternal HBV-infection status, presence of hepatitis B e antigen and HBV mutat ion.CONCLUSION: Differences in peripheral T-cell subpopulation profi les can be found in different clinical stages of chronic HBV infection. T-cell impairment is signifi cantly associated with HBV load.