title: Regulation of leukotriene B4 generation from human polymorphonuclear granulocytes after stimulation with formyl-methionyl-leucyl phenylalanine: effects of pertussis and cholera toxins.
abstract: The effects of holotoxins and toxin subunits from Bordetella pertussis and Vibrio cholerae strains on intact and digitonin-permeabilized human polymorphonuclear neutrophils were studied. Our data clearly demonstrate that formyl-methionyl-leucyl-phenylalanine (fMLP)-induced generation of chemotactic active leukotriene B4 was inhibited by both holotoxins as well as by their isolated enzymatic A protomers. In contrast, the respective binding components (B oligomers) did not affect leukotriene formation. Priming of digitonin-permeabilized neutrophils with either guanylylimidodiphosphate or inositol trisphosphate increased subsequent stimulation with fMLP. In contrast, diacylglycerol decreased fMLP-induced leukotriene B4 formation, but inositol trisphosphate and diacylglycerol had no effect on inhibition mediated by the toxins. In addition, pertussis and cholera toxins reduced the specific binding of [3H]fMLP. Scatchard plot analysis revealed that the observed decrease of peptide binding was due to a reduced number of receptor sites. The fMLP-stimulated [3H]guanylylimidodiphosphate binding and GTPase activity used as parameters for the activation of G proteins were decreased in parallel. These results suggest altered chemotactic receptor numbers and G-protein functions responsible for the toxin-dependent suppression of fMLP-mediated response for neutrophils.
authors.affiliation: Lehrstuhl für Medizinische Mikrobiologie und Immunologie, Ruhr-Universität Bochum, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Hensler
authors.forename: M
authors.initials: M
authors.lastname: Köller
authors.forename: W
authors.initials: W
authors.lastname: König
mesh_terms: D002772:Cholera Toxin / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007975:Leukotriene B4 / Q000276:immunology*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism; D010539:Permeability; D010716:Phosphatidylinositols / Q000276:immunology / Q000378:metabolism; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000276:immunology; D015398:Signal Transduction; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
chemical_list: D010716:Phosphatidylinositols; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D010566:Virulence Factors, Bordetella; D007975:Leukotriene B4; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002772:Cholera Toxin; D019204:GTP-Binding Proteins