Interleukin-21 administration leads to enhanced antigen-specific T cell responses and natural killer cells in HIV-1 vaccinated mice

•​Mouse IL-21 could not increase antibody binding capacity to HIV-1 GP140.•Mouse IL-21 enhanced Th1 type immune response.•Mouse IL-21 increased the percentages of HIV-1 specific CD4+ T and CD4+ TEM cells.•​Mouse IL-21 increased HIV-1 specific multifunctional CD4+ T and CD4+ TEM cells.•Mouse IL-21 increased the frequency of NK cells.