While antibodies directed against proteinase 3 (PR3-ANCA) and myeloperoxidase (MPO-ANCA) have a high specificity for the diagnosis of systemic vasculitis, they may also be found as an epiphenomenon of acute viral infection.
Medical University, Graz, Department of Internal Medicine, Division of Rheumatology, Auenbruggerplatz 15, A-8036 Graz, Austria. josef.hermann@meduni-graz.at