title: In vitro prevention and reversal of lipopolysaccharide desensitization by IFN-gamma, IL-12, and granulocyte-macrophage colony-stimulating factor.
abstract: LPS tolerance is characterized by a diminished monocytic synthesis of TNF-alpha and, interestingly, IL-10 after LPS restimulation. We wondered whether granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-12, and IFN-gamma can prevent or reverse this down-regulation of TNF-alpha and IL-10 production. The LPS-induced TNF-alpha amounts in desensitized PBMC treated with GM-CSF, IFN-gamma, or IL-12 and in naive, non-cytokine-primed cultures were similar, while much more TNF-alpha was induced in cytokine-primed naive cells. The effect of IL-12 was dependent on the presence of nonmonocytic cells and could be completely blocked with an IFN-gamma antiserum. Treatment of LPS-desensitized pure monocytes with IFN-gamma or GM-CSF resulted in a very high TNF-alpha expression and no difference to cytokine-primed naive monocytes was evident any longer. While IFN-gamma and IL-12 decreased IL-10 expression in naive PBMC, it was increased by both and by GM-CSF in LPS-tolerant cultures. Again, only IL-12 was dependent on the presence of nonmonocytic cells. For prevention of LPS tolerance, similar results were obtained. Recently, we have shown that IL-10 and TGF-beta mediate LPS desensitization in vitro and can be used to establish LPS hyporesponsiveness in the absence of LPS. IFN-gamma and GM-CSF prevented and reversed down-regulation of TNF-alpha and IL-10 synthesis also in the model of IL-10/TGF-beta1-induced LPS hyporesponsiveness, while IL-12 was ineffective because of its obvious inability to induce IFN-gamma. In summary, after LPS desensitization/hyporesponsiveness, IFN-gamma and GM-CSF tended to normalize pro- and anti-inflammatory monocytic behavior. Our results suggest that during LPS desensitization/hyporesponsiveness, monocytes acquire a hitherto unknown functional state with an altered reaction to biologic response modifiers.
authors.affiliation: Institute of Medical Immunology, Charité Medical School, Humboldt-University Berlin, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Randow
authors.forename: W D
authors.initials: WD
authors.lastname: Döcke
authors.forename: D S
authors.initials: DS
authors.lastname: Bundschuh
authors.forename: T
authors.initials: T
authors.lastname: Hartung
authors.forename: A
authors.initials: A
authors.lastname: Wendel
authors.forename: H D
authors.initials: HD
authors.lastname: Volk
mesh_terms: D003888:Desensitization, Immunologic; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000494:pharmacology*; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects; D007371:Interferon-gamma / Q000096:biosynthesis / Q000494:pharmacology*; D018664:Interleukin-12 / Q000096:biosynthesis / Q000494:pharmacology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology* / Q000633:toxicity*; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; D018664:Interleukin-12; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor