Induction of a 26-kDa membrane-form tumor necrosis factor (TNF)-alpha in human alveolar macrophages.
The expressions of a membrane form of TNF (m-TNF) by human alveolar macrophages (AM) and autologous blood monocytes from healthy donors were examined. Upon lipopolysaccharide (LPS) stimulation, AM produced 26-kDa TNF-alpha on their cell surface. We designed a bioassay for measuring m-TNF in which macrophages were fixed with paraformaldehyde after stimulation for 18 h, then m-TNF activity was assessed as cytotoxicity of fixed macrophages on L929 cells. This assay was specific to m-TNF because: 1) no soluble factors were contributed to the cytotoxicity of fixed AM, 2) anti-TNF-alpha monoclonal antibody completely neutralized m-TNF activity, and 3) m-TNF activity was not altered after low-pH or high-salt treatment. On LPS stimulation, AM produced significant amounts of m-TNF earlier than TNF-alpha secretion. AM also expressed significant amounts of m-TNF when stimulated with other bacterial components and their derivatives. Interleukin (IL)-4 suppressed both m-TNF production and TNF-alpha secretion. p-Toluene-sulfonyl-L-arginine methyl ester (TAME) inhibited specifically TNF-alpha secretion and not m-TNF expression. Although blood monocytes produced small amounts of m-TNF, monocyte-derived macrophages showed enhanced m-TNF after cultivation with GM-CSF for 10 days. These findings indicate that m-TNF is expressed as a step in the TNF-alpha producing system, and suggest that m-TNF may play important roles in exhibition of macrophage function in situ.
Nii
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Third Department of Internal Medicine, University of Tokushima, School of Medicine, Japan.
Sone
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Orino
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Ogura
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T
D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000328:Adult; D001681:Biological Assay; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D008970:Molecular Weight; D009000:Monocytes / Q000166:cytology / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010844:Picibanil / Q000494:pharmacology; D011994:Recombinant Proteins / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology
D000276:Adjuvants, Immunologic; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D009842:Oligopeptides; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4; D010844:Picibanil; C039537:heptanoyl-gamma-D-glutamyl-L-meso-diaminopimelyl-D-alanine