Antineutrophil cytoplasmic autoantibodies in the immunodiagnosis of systemic necrotizing vasculitis.

If testing of ethanol-fixed neutrophils remains the most commonly used method to screen for ANCA. C-ANCA is highly sensitive and specific for Wegener's granulomatosis if strict criteria in defining this IF pattern are followed. P-ANCA is not specific for MPO-ANCA, when used as a screening test. Because of the increasing recognition of atypical cytoplasmic staining patterns and the lack of specificity of nuclear staining of neutrophils for MPO-ANCA, confirmatory testing by ELISA is advisable in all cases of atypical neutrophil cytoplasmic staining and in all cases of neutrophil nuclear or perinuclear staining.