title: Interleukin 12 synergizes with B7/CD28 interaction in inducing efficient proliferation and cytokine production of human T cells.
abstract: Several receptors and counter-receptor pairs on T cells and on antigen-presenting cells (APCs) deliver costimulatory signals to T cells during antigen presentation. The CD28 receptor on T cells with its ligand B7 represents one of the best characterized and most important examples of this costimulation. We show here that interleukin 12 (IL-12), a cytokine also produced by APCs (monocyte/macrophages and B cells) and active on T and natural killer cells, has a strong synergistic effect with the B7/CD28 interaction in inducing proliferation and cytokine production in both mitogen-activated and freshly isolated peripheral blood T cells. Together with anti-CD28 antibodies, IL-12 induces proliferation of T cells to levels higher than those obtained with IL-2 stimulation and it is effective at IL-12 concentrations 100- to 1,000-fold lower than effective concentrations of IL-2. The proliferative effect of anti-CD28 and IL-12 is resistant to moderate doses of cyclosporin A and is largely independent of endogenous IL-2, IL-12, in synergy with anti-CD28 or B7-transfected cells, is most effective in inducing interferon gamma (IFN-gamma) production, but production of tumor necrosis factor alpha and granulocyte/macrophage colony-stimulating factor is also observed. IL-12-induced IFN-gamma production in peripheral blood mononuclear cells is inhibited by the chimeric molecule CTLA-4 immunoglobulin, which prevents binding of CD28 to B7, suggesting that endogenous B7 on the mononuclear cells and IL-12 cooperate in inducing IFN-gamma production. IL-10 inhibits both IL-12 production and B7 expression on monocytes. These two effects are largely responsible for the ability of IL-10, acting on accessory cells, to inhibit IFN-gamma production by lymphocytes, because anti-CD28 antibodies and IL-12 can reverse the inhibitory effect of IL-10 on IFN-gamma production. Our results in vitro suggest that the synergy between B7 and IL-12, a surface antigen and a soluble product of APCs, respectively, plays a role in regulating T cell activation and immune response in the microenvironment of inflamed tissues.
authors.affiliation: Wistar Institute of Anatomy and Biology, University of Pennsylvania School of Medicine, Philadelphia 19104.
authors.forename: M
authors.initials: M
authors.lastname: Kubin
authors.forename: M
authors.initials: M
authors.lastname: Kamoun
authors.forename: G
authors.initials: G
authors.lastname: Trinchieri
mesh_terms: D000818:Animals; D018122:B7-1 Antigen / Q000502:physiology*; D018106:CD28 Antigens / Q000502:physiology*; D016466:CHO Cells; D006224:Cricetinae; D016207:Cytokines / Q000096:biosynthesis*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000494:pharmacology; D018664:Interleukin-12; D007376:Interleukin-2 / Q000502:physiology; D007378:Interleukins / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D013601:T-Lymphocytes; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D018122:B7-1 Antigen; D018106:CD28 Antigens; D016207:Cytokines; D007376:Interleukin-2; D007378:Interleukins; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D018664:Interleukin-12; D007371:Interferon-gamma