MPO and granulomatosis with polyangiitis: As airway disease is a well-described feature of GPA, ANCA by both methods (indirect immunofluorescence and antigen-specific ELISA, both by Euroimmun AG, Lübeck, Germany) were performed, with the following results: P-ANCA 1:20, MPO-ANCA 128 U/mL (normal <20), negative PR3-ANCA.