Interleukin-21 plays an important role in CD8 T-cell activation and poor outcome in HIV infection.

To present the relationship between high CD8+ T-cell activation and poor outcome in HIV-1 pathogenesis. We hypothesized that the decrease of interleukin-21 (IL-21) levels would lead to alterations in survival of elevated immune activation with disease progress. Fifty-eight HIV-1-seropositive subjects and 21 uninfected healthy control volunteers were recruited in this study. The serum IL-21 concentrations and the levels of expression of CD38, HLA-DR, and IL-21 receptor in CD8 T cells were detected by flow cytometry. The percentages of both CD38 and HLA-DR cells in CD8 T cells were significantly inversely related to the serum IL-21 levels. IL-21 plays an important role in the mechanism of elevated CD8+ T cell immune activation leading to poor outcome in HIV-1 pathogenesis, which will be helpful for the development of current and future anti-HIV strategies.