Heterogeneity of anti-PR3 associated disease in Hong Kong

Thirty seven patients tested positive for antibody against proteinase 3 (anti-PR3) using either one of the two in-house ELISA methods at the Immunology Laboratory, University of Hong Kong. All except three were Chinese. Systemic vasculitis was diagnosed in 13 patients. However, the positive predictive value of anti-PR3 for Wegener's granulomatosus was low (22%). The commonest presenting feature was respiratory (32%). Both respiratory and renal symptoms were commonly reported in anti-PR3 positive patients as in previous studies. In this largely Chinese population, there is marked variability in the spectrum of diseases associated with anti-PR3; though many had vasculitic diseases, some were diagnosed with other conditions such as inflammatory bowel diseases and respiratory infection. In contrast with series in white people, antimyeloperoxidase rather than anti-PR3 associated disease is more prevalent in Chinese patients.