title: Interleukin 2 induces CD8+ T cell-mediated suppression of human immunodeficiency virus replication in CD4+ T cells and this effect overrides its ability to stimulate virus expression.
abstract: The nonlytic suppression of human immunodeficiency virus (HIV) production from infected CD4+ T cells by CD8+ lymphocytes from HIV-infected individuals is one of the most potent host-mediated antiviral activities observed in vitro. We demonstrate that the pleiotropic cytokine interleukin 2 (IL-2), but not IL-12, is a potent inducer of the CD8+ HIV suppressor phenomenon. IL-2 induces HIV expression in peripheral blood or lymph node mononuclear cells from HIV-infected individuals in the absence of CD8+ T cells. However, IL-2 induces CD8+ T cells to suppress HIV expression when added back to these cultures, and this effect dramatically supersedes the ability to IL-2 to induce HIV expression. Five to 25 times fewer CD8+ cells were required to obtain comparable levels of inhibition of viral production if they were activated in the presence of IL-2 as compared with IL-12 or no exogenous cytokine. Furthermore, IL-2 appeared either to induce a qualitative increase in HIV suppressor cell activity or to increase the relative frequency of suppressor cells in the activated (CD25+) CD8+ populations. Analyses of proviral levels in peripheral blood mononuclear cells suggest that CD8+ T cell-mediated lysis of in vivo infected cells is not induced by IL-2. These results have implications for our understanding of the effects of impaired IL-2 production during HIV disease as well as the overall effects of IL-2-based immunotherapy on HIV replication in vivo.
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000382:microbiology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000254:growth & development*; D006801:Humans; D018664:Interleukin-12 / Q000502:physiology; D007376:Interleukin-2 / Q000502:physiology*; D008213:Lymphocyte Activation / Q000187:drug effects; D015375:Receptors, Interleukin-2 / Q000032:analysis / Q000502:physiology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D014779:Virus Replication
chemical_list: D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D018664:Interleukin-12