title: Functional and biochemical characteristics of a murine interleukin 2 receptor-inducing factor.
abstract: High density (resting) murine Lyt-2+ T cells exposed in vitro to the ligand concanavalin A (Con A) remain interleukin 2 (IL 2) unresponsive, i.e. do not express functional IL 2 receptors, unless reconstituted with accessory cells. This finding provides a bio-assay to define functional and biochemical characteristics of an IL 2 receptor-inducing factor (RIF). RIF bioactivity as secreted from the macrophage cell line P388-D1 is associated with a trypsin-sensitive protein of 44 kDa which does not need to be glycosylated and which binds to and can be eluted from hydroxylapatite and phenyl-Sepharose. While both RIF and IL 1 are produced by accessory cells the lymphokines separate from each other according to functional and biochemical criteria. Either accessory cells, RIF or the protein kinase C activator phorbol myristate acetate can substitute for each other and are equally active for the induction of IL 2 responsiveness in high-density Lyt-2+ T cells exposed to Con A. To explain these results we conclude that in the mitogen system used, induction of IL 2 responsiveness (activation) represents a two-step event in which first cross-linking of cell surface structures by the ligand Con A excites the responder T cells, which subsequently respond to the accessory cell product RIF.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D051379:Mice; D008809:Mice, Inbred C3H; D008808:Mice, Inbred CBA; D011948:Receptors, Antigen, T-Cell / Q000096:biosynthesis*; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000378:metabolism; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D007376:Interleukin-2; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate