Accumulating evidence demonstrates that CD8+CD28- regulatory T cells increase in chronic viral infection as well as tumorigenesis. However, it is still not clear about their characteristics in hepatitis B virus (HBV) infection. In addition, it is not understood whether this regulatory immune subset is distinct from CD4+CD25high regulatory T cells in the aspect of impact on or relationship to the progression of HBV infection. Hence, we investigated their dynamics and compared their correlations with clinical parameters in the chronic and advanced phases of HBV infection. The data showed that compared with healthy controls, the frequencies of CD28+CD8- and CD4+CD25high T cells increased in both chronic and advanced phases, while there is no significant difference between the two case groups. Interestingly, we found that in chronic phase, the frequency of CD8+CD28- subset was negatively correlated with the levels of alanine aminotransaminase (ALT) and aspartate aminotransferase (AST), respectively, and did not present association with HBV DNA load, whereas that of CD4+CD25high T cells was positively correlated with HBV DNA load and the levels of ALT and AST, respectively. Amazingly, in advanced phase, the frequency of CD4+CD25high T cells was negatively correlated with HBV DNA load and the levels of ALT, respectively, while there is no significant correlation between the frequency of CD8+CD28- subset and those clinical parameters. Thereby, our findings demonstrated that CD28+CD8- and CD4+CD25high regulatory T cells might exert distinct effect on modulating antiviral immune responses and mitigate immunomediated liver damage in different phases of HBV infection, which represent potential prognostic markers and therapeutic targets for HBV-infected patients based on further exploration of detailed mechanism.
Keywords: CD28+CD8− regulatory T cells; CD4+CD25high regulatory T cells; hepatitis B virus infection; liver damage.