AIM:To study and contrast the difference of activation-induced cell death(AICD) in peripheral blood T-lymphocytes(PBL-Ts) from patients with chronic hepatitis B (CHB) and the normal people in vitro,and to explore the role of AICD in chronic hepatitis B virus (HBV) infection and the pathogenesis of CHB.METHODS:Twenty-five patients and fourteen healthy people were selected for isolation of PBL-Ts.During cultivation,anti-CD3mAb,PMAand ionomycin were used for AICD of PBL-Ts.AICD ratio of PBL-Ts was detected with TdT-mediated dUTP nick end labeling and assessed by flow cytometry.RESULTS:When induced with anti-CD3,PMA and ionomycin in vitro,AICD ratio of PBL-Tsfrom CHB patients was significantly higher than that from healthy control (17.24±1.21 vs.6.63±1.00,P<0.01) and that from CHB patients without induction (17.24±1.21 vs.9.88±1.36,P<0.01).There was a similar AICD ratio of PBL-Ts between induction group and without induction group,but no difference was found before and after induction in healthy control.The density of INF-γ in culture media of induction groups of CHBwas lower than that of other groups (P<0.01).There was no difference between these groups in density of IL-10 (P>0.05).CONCLUSION:When induced during cultivation in vitro,PBL-Ts from CHB occur AICD very common.This phenomenon has a potentially important relation with pathogenesis of CHB and chronicity of HBV infection.