title: Expression of myeloperoxidase (MPO) by neutrophils is necessary for their activation by anti-neutrophil cytoplasm autoantibodies (ANCA) against MPO.
abstract: Anti-neutrophil cytoplasm autoantibodies (ANCA) directed against proteinase-3 and myeloperoxidase (MPO) activate tumor necrosis factor-alpha-primed neutrophils in vitro. We used neutrophils from one completely and one partially MPO-deficient donor to assess the requirement of MPO expression for neutrophil activation by anti-MPO antibodies. The MPO deficiencies were defined enzymatically, by immunocytochemistry and by immunoblotting. The mutations in the MPO genes of these donors were identified as a combination of a novel splice-site mutation at the 3' end of intron 11 (A-2-->C), a deletion of 14 nucleotides in exon 9 (A1555-C1568), and a novel C1907 --> T (636Thr-->Met) substitution in exon 11 in the completely MPO-deficient donor and as the same splice-site mutation and a novel C995 --> T (332Ala-->Val) substitution in exon 7 in the partially MPO-deficient donor. Monoclonal antibody 4.15 against MPO and MPO-ANCA-immunoglobulin G induced no superoxide anion production in these MPO-deficient neutrophils despite a normal production induced by other stimuli. Thus, the presence of MPO is a conditio sine qua non for neutrophil activation by anti-MPO antibodies. Moreover, we demonstrated that by means of these MPO-deficient cells, hydrogen peroxide may diffuse from neutrophils to surrounding cells, which may contribute to the damage induced by oxygen radicals in the pathology of systemic vasculitides.
authors.affiliation: Département d'Hématologie-Immunologie-Cytogénétique, Centre Hospitalier de Valenciennes, France. reumaux-d@ch-valenciennes.fr
authors.forename: Dominique
authors.initials: D
authors.lastname: Reumaux
authors.forename: Martin
authors.initials: M
authors.lastname: de Boer
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Meijer
authors.forename: Patrick
authors.initials: P
authors.lastname: Duthilleul
authors.forename: Dirk
authors.initials: D
authors.lastname: Roos
mesh_terms: D019268:Antibodies, Antineutrophil Cytoplasmic / Q000494:pharmacology*; D002448:Cell Adhesion; D004252:DNA Mutational Analysis; D004058:Diffusion; D005456:Fluorescent Dyes; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D018375:Neutrophil Activation; D009504:Neutrophils / Q000201:enzymology* / Q000276:immunology; D010455:Peptides / Q000032:analysis; D009195:Peroxidase / Q000172:deficiency / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D020112:Rhodamine 123; D013481:Superoxides / Q000378:metabolism
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D005456:Fluorescent Dyes; D010455:Peptides; D013481:Superoxides; D020112:Rhodamine 123; D006861:Hydrogen Peroxide; D009195:Peroxidase