title: NB1 mediates surface expression of the ANCA antigen proteinase 3 on human neutrophils.
abstract: Antineutrophil cytoplasmic antibodies (ANCAs) with specificity for proteinase 3 (PR3) are central to a form of ANCA-associated vasculitis. Membrane PR3 (mPR3) is expressed only on a subset of neutrophils. The aim of this study was to determine the mechanism of PR3 surface expression on human neutrophils. Neutrophils were isolated from patients and healthy controls, and hematopoietic stem cells from cord blood served as a model of neutrophil differentiation. Surface expression was analyzed by flow cytometry and confocal microscopy, and proteins were analyzed by Western blot experiments. Neutrophil subsets were separated by magnetic cell sorting. Transfection experiments were carried out in HEK293 and HL60 cell lines. Using neutrophils from healthy donors, patients with vasculitis, and neutrophilic differentiated stem cells we found that mPR3 display was restricted to cells expressing neutrophil glycoprotein NB1, a glycosylphosphatidylinositol (GPI)-linked surface receptor. mPR3 expression was decreased by enzymatic removal of GPI anchors from cell membranes and was absent in a patient with paroxysmal nocturnal hemoglobinuria. PR3 and NB1 coimmunoprecipitated from and colocalized on the neutrophil plasma membrane. Transfection with NB1 resulted in specific PR3 surface binding in different cell types. We conclude that PR3 membrane expression on neutrophils is mediated by the NB1 receptor.
authors.affiliation: Franz Volhard Clinic, Department of Nephrology and Hypertension, Medical Faculty of the Charité, HELIOS-Klinikum, Berlin, Germany.
authors.forename: Sibylle
authors.initials: S
authors.lastname: von Vietinghoff
authors.forename: Gisela
authors.initials: G
authors.lastname: Tunnemann
authors.forename: Claudia
authors.initials: C
authors.lastname: Eulenberg
authors.forename: Maren
authors.initials: M
authors.lastname: Wellner
authors.forename: M
authors.initials: M
authors.lastname: Cristina Cardoso
authors.forename: Friedrich C
authors.initials: FC
authors.lastname: Luft
authors.forename: Ralph
authors.initials: R
authors.lastname: Kettritz
mesh_terms: D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D000954:Antigens, Surface / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology; D058851:GPI-Linked Proteins; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D007519:Isoantigens / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D053146:Myeloblastin / Q000276:immunology / Q000378:metabolism*; D009504:Neutrophils / Q000201:enzymology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000502:physiology*; D014162:Transfection
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D000954:Antigens, Surface; C407242:CD177 protein, human; D058851:GPI-Linked Proteins; D017261:Glycosylphosphatidylinositols; D007519:Isoantigens; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D053146:Myeloblastin