LESIONS OF THE RESPIRATORY-TRACT ASSOCIATED WITH THE FINDING OF ANTINEUTROPHIL CYTOPLASMIC AUTOANTIBODIES WITH A PERINUCLEAR STAINING PATTERN

Objective: To characterize the clinicopathologic spectrum of respiratory tract involvement in patients with positive results of immunofluorescence microscopy for anti-neutrophil cytoplasmic autoantibodies with a perinuclear staining pattern (p-ANCA) and to assess the clinical value of p-ANCA testing. Design: We retrospectively reviewed the medical records of all patients at Mayo Clinic Rochester in whom p-ANCA were detected by indirect immunofluorescence microscopy during 1992. Material and Methods: Additional target antigen identification was performed with use of enzyme-linked immunosorbent assays for antibodies against myeloperoxidase (MPO) and proteinase 3. We summarized the clinical findings in MPO-positive and MPO-negative patients. Results: Sera were positive for p-ANCA in 42 of 2,381 patients (1.8%). In 13 of these 42 patients (31%), the respiratory tract was involved. Twelve patients had chest roentgenographic abnormalities, including a diffuse alveolar filling pattern (N = 8), a diffuse interstitial pattern (N = 2), and a combined interstitial and alveolar pattern (N = 2); three others had nasal inflammation. Ten of 16 sera tested were positive for MPO, and proteinase 3 antibodies were detected in 1 specimen. All patients with alveolar hemorrhage were positive for MPO antibodies. Conclusion: Testing for p-ANCA by immunofluorescence microscopy discloses a wide range of clinical disorders distinct from the main cytoplasmic-staining ANCA-associated disease-namely, Wegener's granulomatosis. In particular, the respiratory tract is affected much less frequently. Further evaluation of positive p-ANCA immunofluorescence test results by enzyme-linked immunosorbent assay to determine whether MPO is the target antigen is necessary to obtain clinically useful information from this test.