title: Down regulation of the receptors for tumor necrosis factor by interleukin 1 and 4 beta-phorbol-12-myristate-13-acetate.
abstract: Binding of radiolabeled tumor necrosis factor (TNF) to cell surface receptors was markedly reduced in human foreskin fibroblasts and cells from SV-80 and HeLa cell lines subsequent to treatment with interleukin 1 (IL-1) or 4 beta-phorbol-12-myristate-13-acetate (PMA). The decrease in TNF binding was initiated within minutes of application of IL-1 or PMA and could not be blocked by cycloheximide, suggesting that it is independent of protein synthesis. Scatchard plot analysis of TNF binding to the SV-80 cells indicated that its decrease in response to IL-1 and PMA reflects a reduced amount of TNF receptors, with no change in their affinity. IL-1 and PMA together had an additive effect on TNF binding. Treatment with TNF did not result in decreased binding of IL-1 to its receptors nor did TNF and IL-1 compete directly for their respective receptors. Human U937 cells on which receptors for IL-1 were below detectable levels exhibited no decrease in TNF binding when treated with IL-1, but did so in response to PMA. In addition to a decrease in TNF receptors, cells treated with IL-1 or PMA exhibited a lesser vulnerability to the cytolytic effect of TNF. The two kinds of changes were not completely correlated. A particularly notable dissimilarity was evident when comparing the rate of their reversal: the TNF receptor level was fully recovered within a few hours of removal of IL-1 or of the water-soluble analogue of PMA, 4 beta-phorbol-12,13-dibutyrate, from pretreated SV-80 cells; yet at that time resistance to the cytotoxicity of TNF was still prominent. These findings indicate that IL-1 as well as tumor-promoting phorbol diesters can down regulate cellular response to TNF by inducing a decrease in the number of receptors for TNF, and apparently through some other effect(s) as well.
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D006023:Glycoproteins / Q000633:toxicity; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D011971:Receptors, Immunologic / Q000502:physiology; D017472:Receptors, Interleukin-1; D018124:Receptors, Tumor Necrosis Factor; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha
chemical_list: D006023:Glycoproteins; D007375:Interleukin-1; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D013755:Tetradecanoylphorbol Acetate