title: The avidity of PR3-ANCA in patients with granulomatosis with polyangiitis during follow-up.
abstract: The objective of this study is to investigate whether the avidity of proteinase-3-anti-neutrophil cytoplasmic antibody (PR3-ANCA) changes during follow-up in different subgroups of patients with granulomatosis with polyangiitis (GPA). We selected 10 patients with renal relapsing GPA, 10 patients with renal non-relapsing GPA and 10 patients with non-renal relapsing GPA. In all patients, an ANCA rise occurred during remission. The avidity was measured using a chaotropic approach at the time of an ANCA rise and at the time of a relapse in relapsing patients or time-matched during remission in non-relapsing patients. No difference was observed in the avidity at the ANCA rise between renal relapsing patients [26·2% (15·5-47·5)], renal patients without a relapse [39·6% (21·2-63·4)] and non-renal relapsing patients [34·2% (21·6-59·5)]. In renal relapsing patients, the avidity increased significantly from the moment of the ANCA rise to the relapse [difference 6·4% (0·0-17·1), P = 0·0273]. The avidity did not increase after an ANCA rise in renal non-relapsing patients [difference 3·5 (-6·0 to 10·1), P = 0·6250] or in non-renal relapsing patients [difference -3·1% (-8·0 to 5·0), P = 0·5703]. The avidity of PR3-ANCA increases after an ANCA rise during follow-up in renal relapsing patients, but not after an ANCA rise in renal patients who remain in remission or in non-renal relapsing patients.
authors.affiliation: Department of Internal Medicine, Division of Nephrology and Clinical Immunology, Maastricht University Medical Center.|Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kemna
authors.affiliation: Institute for Experimental Immunology, Euroimmun, Lübeck, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Schlumberger
authors.affiliation: Department of Internal Medicine, Division of Nephrology and Clinical Immunology, Maastricht University Medical Center.|Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: van Paassen
authors.affiliation: Institute for Experimental Immunology, Euroimmun, Lübeck, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Dähnrich
authors.affiliation: Central Diagnostic Laboratory, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: J G M C
authors.initials: JG
authors.lastname: Damoiseaux
authors.affiliation: Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Cohen Tervaert
mesh_terms: D000328:Adult; D000368:Aged; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood / Q000276:immunology*; D000915:Antibody Affinity; D005260:Female; D005500:Follow-Up Studies; D014890:Granulomatosis with Polyangiitis / Q000276:immunology*; D006801:Humans; D007674:Kidney Diseases / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D053146:Myeloblastin / Q000097:blood / Q000276:immunology*; D012008:Recurrence
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D053146:Myeloblastin
keywords: ANCA-associated vasculitis; PR3-ANCA; avidity; follow-up; granulomatosis with polyangiitis; proteinase 3; relapse; relative avidity index