title: IL-10 inhibits mitogen-induced T cell proliferation by selectively inhibiting macrophage costimulatory function.
abstract: IL-10, a newly designated cytokine primarily produced by the Th2 subset of CD4+ T lymphocytes and Ly-1+ B lymphocytes, has recently been hypothesized to inhibit cytokine production by Th1 T cell clones by blocking accessory cell- (AC) dependent costimulatory function. To evaluate the effect of IL-10 on Con A-induced proliferative responses of resting murine T cells, purified T cells were cultured with different types of AC. The addition of IL-10 produced a 70 to 90% inhibition of resting T lymphocyte proliferation when purified populations of macrophages were used as AC, but had no effect on the AC function of T-depleted spleen cells, activated B cells, dendritic cells, or L cells. The inhibitory effects of IL-10 were inversely related to the concentration of mitogen and could be reversed by the addition of the neutralizing anti-IL-10 mAb, SXC1. The inhibition of macrophage AC function was not related to the induction of a suppressor cytokine as stimulation by mixtures of macrophages and limiting numbers of dendritic cells was not inhibited. The decrease in proliferative responses was primarily secondary to inhibition of IL-2 production although the failure of exogenous IL-2 to completely reconstitute the response suggested that IL-10 may also exert inhibitory effects on the induction of expression of a functional IL-2R. These results are most consistent with a model in which IL-10 inhibits the induction of expression on macrophages of a critical costimulatory molecule that may be constitutively expressed on other types of AC.
authors.affiliation: Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
authors.forename: L
authors.initials: L
authors.lastname: Ding
authors.forename: E M
authors.initials: EM
authors.lastname: Shevach
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002478:Cells, Cultured; D003208:Concanavalin A; D016753:Interleukin-10 / Q000096:biosynthesis / Q000494:pharmacology*; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D015375:Receptors, Interleukin-2 / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D003208:Concanavalin A; D016753:Interleukin-10