title: Comparative analysis of different commercial ELISA systems for the detection of anti-neutrophil cytoplasm antibodies in ANCA-associated vasculitides.
abstract: OBJECTIVE
  To assess the diagnostic performance of 11 commercial PR3- and MPO-ANCA ELISA systems (direct, capture and high sensitive [hs] ELISA).
  
  
  METHODS
  Sera from 90 patients with AAV (GPA, MPA and CSS) and 20 disease controls (SLE; RA) and healthy individuals were tested for the presence of ANCA by IFT and by different ELISAs for the presence of PR3-and MPO-ANCA, respectively. Furthermore, the binding capacity of the IUIS-CDC reference sera for PR3-/MPO-ANCA in different commercial assays was analysed.
  
  
  RESULTS
  Commercial ELISA kits for PR3-ANCA differed moderately in their sensitivity (from 45% to 62.5%). The highest sensitivity for PR3-ANCA was obtained with hs ELISA (kit A) and capture ELISA (kit N). Testing for MPO-ANCA the highest sensitivity (85%) was obtained with direct ELISA (kit D and I). Specificity was high in all kits. Only three PR3-ANCA commercial kits and three MPO-ANCA kits produced binding at the expected value for the IUIS-CDC reference sera (100 U/ml). In all of the kits, serial dilutions of the reference sera did not yield linearity.
  
  
  CONCLUSIONS
  Second (capture) and third (high sensitivity) generation PR3-ANCA ELISA kits are superior to conventional ELISAs. Direct and capture MPO-ANCA ELISAs showed a good overall performance in all kits. Most of the kits have not been standardised to allow their results to be compared.
authors.affiliation: University Hospital Schleswig-Holstein, Campus Lübeck and Klinikum Bad Bramstedt, Dept. of Rheumatology and Immunology, Germany. hollejulia@hotmail.com
authors.forename: Julia U
authors.initials: JU
authors.lastname: Holle
authors.forename: Kristine
authors.initials: K
authors.lastname: Herrmann
authors.forename: Wolfgang L
authors.initials: WL
authors.lastname: Gross
authors.forename: Elena
authors.initials: E
authors.lastname: Csernok
mesh_terms: D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D005858:Germany; D006801:Humans; D053146:Myeloblastin / Q000276:immunology*; D009195:Peroxidase / Q000276:immunology*; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic / Q000592:standards; D012015:Reference Standards; D012680:Sensitivity and Specificity
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D011933:Reagent Kits, Diagnostic; D009195:Peroxidase; D053146:Myeloblastin