Tumor necrosis factor-alpha inhibits cell proliferation and induces class II antigens and cell adhesion molecules in cultured normal human keratinocytes in vitro.
The effects of recombinant human tumor necrosis factor-alpha (TNF) on cell proliferation, cell morphology, and on the expression of class II alloantigens and intercellular adhesion molecule-1 (ICAM-1) were assessed in human keratinocytes cultured in serum-free medium. TNF inhibited cell proliferation in a time- and dose-dependent manner with a minimum effective dose of 10 U/ml and a 50% inhibitory dose of 100 U/ml. However, TNF did not induce cell death, and the growth inhibition induced by TNF was completely reversible after its withdrawal. In vitro combination of TNF with interferon-alpha (IFN-alpha) and IFN-beta resulted in additive growth inhibitory effects, while IFN-gamma enhanced the TNF mediated growth inhibition in a synergistic way. Furthermore, TNF altered the morphology of the growing keratinocytes inducing the appearance of a fusiform, fibroblast-like population. Also, treatment with TNF over 6 days markedly induced the expression of ICAM-1 on the cultured keratinocytes with a minimal effective dose of 10 U/ml, while HLA-DR was only moderately expressed after 1,000 U/ml. TNF did not induce HLA-DQ, but reduced the IFN-gamma induced expression of HLA-DR and HLA-DQ. By immunoelectron microscopy, an intense membrane-bound labeling for ICAM-1 was found after treatment with TNF, clearly pronounced in areas of microvillous membrane protrusions. These results indicate that epidermal keratinocytes are a major target for various biological effects of TNF. We also found that TNF differentially modulates IFN-gamma-induced effects, thus suggesting its potential role in the regulation of inflammatory skin disorders.
Detmar
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Department of Dermatology, University Medical Center Steglitz, Free University of Berlin.
Orfanos
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D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D006684:HLA-DR Antigens / Q000032:analysis; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D015815:Cell Adhesion Molecules; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma