Antineutrophil cytoplasmic antibodies: reporting and diagnostic strategies

It was with great interest that we read the correspondence of Mahler and Fritzler1 on our recent European Vasculitis Study Group (EUVAS) study describing the performance of immunoassays for antineutrophil cytoplasmic antibodies (ANCA) in patients with ANCA-associated vasculitides (AAV).2 In their letter, Mahler and Fritzler raise some interesting points, mainly related to (i) test result interpretation and (ii) diagnostic strategies. Besides, they pointed out that in the EUVAS study only two indirect immunofluorescence (IIF) assays were included, a commercial assay from Inova Diagnostics and a ‘home-made’ assay. They suggested to perform studies with more than two IIF ANCA tests and especially to include assays that are most commonly used in diagnostic laboratories. In a concomitant publication, we presented data on two additional commercial IIF assays, one from Euroimmun and one from Medipan.3 Accordingly, we postulate that we included the most commonly used IIF...