Antineutrophil Cytoplasmic Autoantibodies: Role in Diagnosis, Disease Monitoring, and Prognosis.

Abstract

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis is a rare and potentially fatal autoimmune disorder characterized by pauci-immune necrotizing vasculitis affecting small to medium sized blood vessels. The pathogenic role of ANCAs in ANCA-associated vasculitis is supported by both clinical and experimental evidence, and when used in the proper clinical setting ANCA testing is highly specific for ANCA-associated vasculitis. Testing with both indirect immunofluorescence assay (IFA) and enzyme immunoassay (EIA) may increase sensitivity for ANCA-associated vasculitis, however testing with a high-quality EIA may be used alone. Non-vasculitic conditions and drugs can cause ANCA positivity without manifestations of ANCA-associated vasculitis. We review ANCA testing itself, performance characteristics and specific conditions for the laboratory test, and various conditions when ANCA testing is useful in diagnosis, disease monitoring and selecting treatment.