title: Evaluation of automated multi-parametric indirect immunofluorescence assays to detect anti-neutrophil cytoplasmic antibodies (ANCA) in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).
abstract: OBJECTIVE
  The aim of this multicenter EUVAS study was to evaluate the diagnostic performance of multi-parametric indirect immunofluorescence (IIF) assays to detect anti-neutrophil cytoplasmic antibodies (ANCA) in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).
  
  
  METHODS
  The study included 912 samples from diseased controls and 249 diagnostic samples from GPA (n=183) and MPA (n=66) patients. The performance of two automated multi-parametric assays [Aklides (Medipan/Generic Assays) and EuroPattern (Euroimmun)] combining IIF on cellular and purified antigen substrates was compared with two manual IIF analyses and with commercially available ELISAs for MPO- and PR3-ANCA (Euroimmun).
  
  
  RESULTS
  The area under the curve (AUC) of the receiver operating characteristics (ROC) curve to discriminate AAV from controls was 0.925, 0.848, 0.855 and 0.904 for, respectively, the two manual analyses, Aklides and EuroPattern, and 0.959, 0.921 and 0.886 for, respectively, antigen-specific ELISA, antigen-coated beads, and microdot, respectively. Variation in pattern assignment between IIF methods was observed.
  
  
  CONCLUSIONS
  The performance of IIF depends on the substrate used and the definition of IIF patterns. The performance of automated IIF is improved by multi-parameter testing (combined IIF and antigen-specific testing). Given the variability between IIF methods, the diagnostic importance of this technique is questioned.
authors.affiliation: Department of Internal Medicine, Rheumatology and Immunology, Vasculitis Center Tübingen-Kirchheim, University Hospital Kirchheim, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Csernok
authors.affiliation: Central Diagnostic Laboratory, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Damoiseaux
authors.affiliation: Department of Autoimmune Serology, Statens Serum Institute, Copenhagen, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Rasmussen
authors.affiliation: Department of Internal Medicine, Rheumatology and Immunology, Vasculitis Center Tübingen-Kirchheim, University Hospital Kirchheim, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hellmich
authors.affiliation: Department of Internal Medicine, Section of Nephrology and Immunology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: van Paassen
authors.affiliation: Clinical Department of Laboratory Medicine, University Hospitals Leuven, 3000 Leuven, Belgium; Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Vermeersch
authors.affiliation: Clinical Department of General Internal Medicine, Research Department of Microbiology and Immunology, Laboratory of Clinical Infectious and Inflammatory Disorders, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Daniel
authors.initials: D
authors.lastname: Blockmans
authors.affiliation: Maastricht University, The Netherlands.
authors.forename: Jan-Willem
authors.initials: JW
authors.lastname: Cohen Tervaert
authors.affiliation: Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium; Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium. Electronic address: Xavier.Bossuyt@uzleuven.be.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
mesh_terms: D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods*; D014890:Granulomatosis with Polyangiitis / Q000276:immunology*; D006801:Humans; D055953:Microscopic Polyangiitis / Q000276:immunology*
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic
keywords: Anti-neutrophil cytoplasmic antibodies (ANCA); Granulomatosis with polyangiitis (GPA); Indirect immunofluorescence; Microscopic polyangiitis (MPA)