title: Regulation of interleukin 2 receptor expression: effects of phorbol diester, phospholipase C, and reexposure to lectin or antigen.
abstract: Anti-Tac monoclonal antibody identifies the receptor for interleukin 2 (IL 2, or T cell growth factor) present on activated human T lymphocytes. By using tritiated anti-Tac, we now report a sensitive and specific binding assay to evaluate cell surface IL 2 receptor expression. IL 2 receptors on human peripheral blood lymphocytes can be detected within 6 hr after PHA stimulation. PHA-induced receptor expression is inhibited by actinomycin D and cycloheximide, but not by mitomycin C, suggesting a requirement for de novo RNA and protein synthesis, but not DNA synthesis. Scatchard analysis of [3H]-anti-Tac binding to lymphocytes stimulated with PHA for 3 days revealed from 20,000 to 60,000 molecules of antibody bound per cell, and a Kd of 1 to 3 x 10(-10) mol/l. Sequential binding studies of activated human lymphocytes maintained in long-term culture with IL 2 demonstrated a progressive decline in receptor number correlating with diminished growth rate. Restimulation with lectin or antigen increased the number of IL 2 receptors, suggesting that IL 2 dependent immune responses may be regulated, at least in part, by IL 2 receptor expression. Receptor number was also increased by PMA. Moreover, similar effects were produced by incubation with phospholipase C but not interleukin 1. Because both PMA and phospholipase C result in activation of protein kinase C, these data suggest the possibility that activation of protein kinase C may induce IL 2 receptor expression.
mesh_terms: D000954:Antigens, Surface / Q000032:analysis / Q000276:immunology; D001666:Binding Sites, Antibody; D004357:Drug Synergism; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology; D007519:Isoantigens / Q000276:immunology; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects*; D010704:Phorbols / Q000494:pharmacology*; D010740:Phospholipases / Q000494:pharmacology*; D010835:Phytohemagglutinins / Q000494:pharmacology; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D010738:Type C Phospholipases / Q000494:pharmacology*
chemical_list: D000954:Antigens, Surface; D006131:Growth Inhibitors; D007375:Interleukin-1; D007519:Isoantigens; D010704:Phorbols; D010835:Phytohemagglutinins; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D010740:Phospholipases; D010738:Type C Phospholipases; D013755:Tetradecanoylphorbol Acetate