title: Cytotoxic effects of antibodies to proteinase 3 (C-ANCA) on human endothelial cells.
abstract: Autoantibodies directed against cytoplasmic antigens of neutrophils (ANCA), especially those with specificity for proteinase 3 (PR-3) and myeloperoxidase, are valuable markers for differential diagnosis and monitoring of disease activity in Wegener's granulomatosis (WG) and other vasculitides. Till now, several concepts concerning a direct role of antibodies against PR-3 in the pathogenesis of WG have been discussed. Recently we were able to show that these antibodies recognize PR-3 translocated into the membrane of human endothelial cells. The aim of this study was to investigate putative cytotoxic effects of antibodies to PR-3 on human endothelial cells. Antibodies were obtained by affinity purification of sera from patients with active WG. Purified antibodies to Ro (SS-A), La (SS-B) and RNP served as controls. Purified antibodies to PR-3 displayed a lytic activity against endothelial cells treated with tumour necrosis factor-alpha (TNF-alpha) with the help of cytokine-primed neutrophils as measured in a Cr-release assay. About 100% specific cytotoxicity occurred after 4 h and was independent of complement. Cytotoxic effects were inhibited by coincubation with unprimed neutrophils or preincubation of PR-3 antibodies with purified antigen. Antibodies to Ro (SS-A), La (SS-B) or RNP had no cytotoxic effect. In summary, PR-3 antibody-induced cytotoxicity required (i) expression of PR-3 on the surface of TNF-alpha-treated endothelial cells; and (ii) co-cultivation of cytokine-primed neutrophils. This is to the best of our knowledge the first report on direct cytotoxic effects of PR-3 antibodies on vascular endothelium. Our data give a hint at a PR-3 antibody-mediated mechanism of endothelial injury via antibody-dependent cellular cytotoxicity in WG and other ANCA-related vasculitides.
authors.affiliation: I Medical Department, University of Mainz, Germany.
authors.forename: W J
authors.initials: WJ
authors.lastname: Mayet
authors.forename: A
authors.initials: A
authors.lastname: Schwarting
authors.forename: K H
authors.initials: KH
authors.lastname: Meyer zum Büschenfelde
mesh_terms: D019268:Antibodies, Antineutrophil Cytoplasmic; D000920:Antibody-Dependent Cell Cytotoxicity / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology* / Q000302:isolation & purification; D001324:Autoantigens / Q000276:immunology*; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004730:Endothelium, Vascular / Q000201:enzymology / Q000276:immunology*; D014890:Granulomatosis with Polyangiitis / Q000201:enzymology / Q000276:immunology*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D008947:Mixed Connective Tissue Disease / Q000276:immunology; D053146:Myeloblastin; D012697:Serine Endopeptidases / Q000276:immunology*; D012859:Sjogren's Syndrome / Q000276:immunology
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D001323:Autoantibodies; D001324:Autoantigens; D012697:Serine Endopeptidases; D053146:Myeloblastin