Preliminary study on antigen specific CD8+T cells at different stages of HBV infection / 中国免疫学杂志

ABSTRACT

Objective:To clarify the differences of host immune responses at different stages of HBV infection. Methods:We constructed three HLA-A*0201/HBV tetramers with immunodominant epitopes of core18-27,polymerase 575-583 and envelope 335-343,and analyzed antigen specific CD8+ T cells and the expression of CD127 in peripheral blood mononuclear cells ( PBMCs) from patients infected with HBV using these HLA-A*0201/HBV tetramers. Results: The frequencies and expansion ability of antigen specific CD8+ T cells in most self-limited HBV infected individuals were higher than that in chronically HBV infected patients. In low copy period the frequencies of antigen specific CD8+ T cells were similar to those in immune clearance phase at a high viral load and liver damage and in immune clearance phase, which had no significant correlation with virus quantitation and ALT level. In chronic infection the ability of antigen specific CD8+ T cells proliferation was inversely proportional to the viral titer. In most self-limited HBV infected individuals the IFN-γsecretion functions of antigen specific CD8+ T cells were higher than in chronic infection,but in immune tolerance phase these cells lost the ability. HBsAg level was different at different stages after HBV infectionit was highest in immune tolerance phase,but in immune clearance phase,activity period and low copy period the correlation with HBV DNA replication gradually declined. The frequency of CD8+ CD127+ T cells in chronic HBV infection was lower than the control group and self-limited infection group,especially in immune tolerance with HBeAg+ and immune clearance phase. Conclusion: The frequencies of antigen specific CD8+ T cells are not the main determinant of immune-mediated protection in chronic HBV infection,memory antigen specific CD8+ T cells are not clear or missing,which provides the possibility for therapeutic vaccines and immunization therapy.