How and why should we detect ANCA?

Antineutrophil cytoplasmic antibodies (ANCA) have become mt established too l for the diagnosis of systemic vasculitis. The major role for ANCA testing is in diagnosing renal insufficiency of unknown origin, where a positive t est indicates whether the patient will benefit from immunosuppressive treat ment or not. A negative test result almost completely rules oat the presenc e of systemic vasculitis. In this clinical setting the major antigens for ANCA are proteinase 3 and m yeloperoxidase, and antibodies to these antigens can best be tested by ELIS A. In other clinical settings like inflammatory bowel disease, arthritis an d so on, several other ANCA specificities have been described and the IIF t est is preferred However; the clinical value of these somewhat mor-e esoter ic specificities is doubtful. New developments in assay techniques and bett er knowledge of specific epitopes will lead to tools for the improved diagn osis as well as follow rip of patients during treatment, as has already bee n seen with the capture assay for PR3-ANCA.