Interferon-gamma and polyunsaturated fatty acids increase the binding of lipopolysaccharide to macrophages.
We have previously shown that interferon-gamma (IFN-gamma) increases the polyunsaturated fatty acid content of membrane phospholipids in cells that were sensitive to endotoxin. In this study, IFN-gamma was found to stimulate the binding of endotoxin to the murine macrophage cell line J774.2 and the human monocyte cell line U937. Interferon-gamma-activated J774.2 cells showed a 66% increase in fluoresceine isothiocyanate (FITC) labelled LPS binding (P < 0.0005 vs control cells) and a 49% increase in tritium labelled LPS binding (P < 0.0001 vs control cells). Interferon-gamma also induced a 35% increase in binding of FITC-LPS in U937 cells (P < 0.0001 vs control cells). In contrast, pretreatment of J774.2 cells with interferon-beta (IFN-beta) had no effect on binding of FITC-LPS. Preincubation with exogenously supplied polyunsaturated fatty acids, linoleic and arachidonic acids, resulted in increases of 74% and 69% in FITC-LPS binding, respectively (both P < 0.0005 vs control cells). On the other hand, pretreatment with the saturated fatty acid, palmitic acid, had no effect on FITC-LPS binding. We propose that IFN-gamma-induced changes in the membrane phospholipid fatty acid composition of macrophage-like cells influence the binding of endotoxin.
Darmani
H
H
Department of Medical Microbiology, University of Wales College of Medicine, Cardiff, UK.
Parton
J
J
Harwood
J L
JL
Jackson
S K
SK
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D016650:Fluorescein-5-isothiocyanate; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D008041:Linoleic Acids / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D011994:Recombinant Proteins; D014407:Tumor Cells, Cultured
D005231:Fatty Acids, Unsaturated; D008041:Linoleic Acids; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D016718:Arachidonic Acid; D007371:Interferon-gamma; D016650:Fluorescein-5-isothiocyanate