Last reviewed 01/2018

Two ANCA patterns were originally identified by indirect immunofluorescence (IIF)

  • 'classical' C-ANCA is associated with antibodies reacting with the 29–30 kDa elastinolitic enzyme, serine proteinase 3 (PR3)
    • composed of 229 amino acids and found in the azurophilic granules of neutrophils and monocytes
    • studies have shown that when the IIF and ELISA results are combined, the presence of C-ANCA and anti-PR3 has 99% specificity for the diagnosis of primary systemic vasculitis
      • classical C-ANCA pattern on IIF and/or anti-PR3 are predominantly found in patients with Wegerner's granulomatosis
        • C-ANCA is a sensitive and specific test for WG - 90% of patients with Wegener's granulomatosis are C-ANCA positive.