A novel enzyme-linked immunosorbent assay using a mixture of human native and recombinant proteinase-3 significantly improves the diagnostic potential for antineutrophil cytoplasmic antibody-associated vasculitis

Ann Rheum Dis. 2009 Feb;68(2):228-33. doi: 10.1136/ard.2007.086579. Epub 2008 Mar 28.


Background: Antineutrophil cytoplasmic antibodies (ANCA) with a C-ANCA or P-ANCA pattern are detected in ANCA-associated vasculitis (AAV). While in most patients with AAV a C-ANCA pattern is due to reactivity with proteinase-3 (PR3)-ANCA, some C-ANCA-positive sera do not react with PR3.

Objective: The development and evaluation of a direct enzyme-linked immunosorbent assay (ELISA) for PR3-ANCA with increased sensitivity.

Methods: A mixture of human native (hn) and human recombinant (hr) PR3 was used as antigen coating. The resulting ELISA (anti-PR3-hn-hr) was compared with ELISAs using directly coated hn-PR3 or hr-PR3, as well as with a hn-PR3 capture ELISA. Assay characteristics were determined in patients with AAV (n = 248), with special attention for those patients with C-ANCA (n = 132), as well as disease controls (n = 585) and healthy controls (n = 429). Additionally, for prediction of relapses serial samples of 46 patients with PR3-AAV were analysed.

Results: At a predefined specificity of 99% both ELISAs containing hr-PR3 revealed a substantial increase in sensitivity. For the prediction of relapses by rises in PR3-ANCA titres the capture ELISA was most optimal (odds ratio 12.5). With an odds ratio of 8.9 the novel anti-PR3-hn-hr ELISA was second best.

Conclusions: Owing to the very high sensitivity of the novel anti-PR3-hn-hr ELISA for the detection of PR3-ANCA in C-ANCA-positive samples of patients with AAV this assay has an excellent diagnostic performance. This feature is combined with a good predictability of clinical relapses in patients with PR3-AAV. These characteristics challenge the dogma that, for detection of PR3-ANCA, capture ELISAs are superior for diagnosis and follow-up.

Publication types

  • Evaluation Study

MeSH terms

  • Antibodies, Antineutrophil Cytoplasmic / blood*
  • Autoimmune Diseases / diagnosis*
  • Autoimmune Diseases / immunology
  • Biomarkers / blood
  • Enzyme-Linked Immunosorbent Assay / methods
  • Humans
  • Myeloblastin / immunology*
  • Prognosis
  • Recombinant Proteins / immunology
  • Recurrence
  • Sensitivity and Specificity
  • Vasculitis / diagnosis*
  • Vasculitis / immunology


  • Antibodies, Antineutrophil Cytoplasmic
  • Biomarkers
  • Recombinant Proteins
  • Myeloblastin