The role of CD4~+CD25~+ regulatory T cells in the pathogenesis of severe hepatitis B

Objective To study the possible role of CD4+CD25+ Regulatory T cells in the pathogenesis of severe hepatitis B patients and the control of HBV replication.Methods The frequency of CD4+CD25+T cells in the peripheral blood mononuclear cells(PBMCs)from 30 cases of severe hepatitis B,20 cases of chronic hepatitis B,20 cases of chronic asymptomatic HBV carriers and 10 healthy controls were determined by flow cytometry and their serum HBV DNA levels were detected by Quantitative Fluorogenic PCR.Results A lower proportion of CD4+CD25+ Regulatory T Cells in PBMCs was found in severe hepatitis B patients(mean%,2.63± 0.83).than that of chronic hepatitis B patients(mean%,4.15±1.17,P0.05),chronic asymptomatic HBV carriers(mean%,8.32±2.72,P0.01)and healthy controls[(8.10±2.65)%,P0.01].There was significantly difference in the frequency of CD4+CD25+ Regulatory T Cells in PBMCs between chronic hepatitis B patients and asymptomatic HBV carriers(P0.05).But no statistically significant differences were found between asymptomatic HBV carriers and healthy controls(P0.05).There were significant differences in HBV DNA serum levels between severe hepatitis B patients(1.2×104 copies/ml)and chronic hepatitis B patients(2.3×106 copies/ml)(P0.01),chronic asymptomatic HBV carriers(7.8×105 copies/ml)(P0.01).But no significant differences were found between asymptomatic HBV carriers and chronic hepatitis B patients.Furthermore,correlation analysis showed that there was positive correlation between serum HBV DNA levels and the frequency of CD4+CD25+ regulatory T cells in PBMCs in hepatitis B patients:r_1= 0.447(asymptomatic HBV carriers,P0.05);r_2=0.453(chronic hepatitis B patients,P0.05);r_3=0.482(severe hepatitis B patients,P0.01).Conclusion CD4+CD25+ regulatory T cells could suppress T cell response against hepatitis B virus and correlate with the virus load of hepatitis B.CD4+CD25+ regulatory T cells may play an important role in the immune homeostasis related to the progression of hepatitis B and the elimination of HBV.