title: Protein Fv produced during viral hepatitis is an endogenous immunoglobulin superantigen activating human heart mast cells.
abstract: Protein Fv, an endogenous protein produced in the liver, is released in biological fluids during viral hepatitis. Acute and chronic viral hepatitis can be associated with cardiovascular derangements. Protein Fv induced the release of histamine, tryptase and the de novo synthesis of prostaglandin D(2) and cysteinyl leukotriene C(4) from mast cells isolated from human heart tissue (HHMC). Protein Fv absorbed with protein A-Sepharose coated with polyclonal IgG did not induce histamine secretion. The maximal percent histamine secretion induced by protein Fv correlated (r(s) = 0.60; p < 0.05) with that induced by anti-IgE, whereas there was no correlation between the release caused by proteins Fv and C5a. Preincubation of HHMC with protein Fv or anti-IgE caused complete cross-desensitization to subsequent challenge with heterologous stimulus. HHMC from which IgE had been dissociated no longer released histamine in response to anti-IgE and protein Fv. A human monoclonal IgE blocked both anti-IgE- and protein Fv-induced release. Three human monoclonal IgM V(H)3(+) inhibited protein-Fv-induced secretion of histamine from HHMC, whereas monoclonal IgM V(H)6(+) did not inhibit the release induced by protein Fv. Protein Fv acts as an endogenous immunoglobulin superantigen by interacting with the V(H)3 domain of IgE to induce the release of mediators from HHMC.
authors.affiliation: Division of Clinical Immunology and Allergy, University of Naples Federico II, Naples, Italy.
authors.forename: Arturo
authors.initials: A
authors.lastname: Genovese
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Borgia
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bouvet
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Detoraki
authors.forename: Amato
authors.initials: A
authors.lastname: de Paulis
authors.forename: Marcello
authors.initials: M
authors.lastname: Piazza
authors.forename: Gianni
authors.initials: G
authors.lastname: Marone
mesh_terms: D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology / Q000378:metabolism; D006526:Hepatitis C / Q000276:immunology* / Q000378:metabolism; D006636:Histamine Release / Q000276:immunology; D006801:Humans; D017997:Leukotriene C4 / Q000276:immunology / Q000378:metabolism; D008222:Lymphokines / Q000096:biosynthesis / Q000276:immunology*; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism; D008875:Middle Aged; D009206:Myocardium / Q000276:immunology* / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000276:immunology / Q000378:metabolism; D015230:Prostaglandin D2 / Q000276:immunology / Q000378:metabolism; D012697:Serine Endopeptidases / Q000276:immunology / Q000378:metabolism; D012795:Sialoglycoproteins / Q000096:biosynthesis / Q000276:immunology*; D018089:Superantigens / Q000096:biosynthesis / Q000276:immunology*; D053802:Tryptases
chemical_list: D000888:Antibodies, Anti-Idiotypic; C089422:Fv protein, human; D008222:Lymphokines; D012795:Sialoglycoproteins; D018089:Superantigens; C026408:anti-IgE antibodies; D017997:Leukotriene C4; D012697:Serine Endopeptidases; D053802:Tryptases; D015230:Prostaglandin D2