RELEVANCE OF CLASSIC ANTINEUTROPHIL CYTOPLASMIC AUTOANTIBODY (C-ANCA)-MEDIATED INHIBITION OF PROTEINASE 3-ALPHA-1-ANTITRYPSIN COMPLEXATION TO DISEASE-ACTIVITY IN WEGENER-GRANULOMATOSIS

In the sera of patients with Wegener's granulomatosis (WG), C-ANCA can be detected that are directed against proteinase 3 (PR3). We have previously observed that C-ANCA interfere with PR3 proteolytic activity and with complexation of PR3 with its major physiologic inhibitor, alpha1-antitrypsin (alpha1AT). In the present study we investigated whether this inhibitory effect of C-ANCA on PR3-alpha1AT complexation correlates with clinical activity of WG. Serial serum samples of eight consecutive patients with histologically proven relapses of WG were tested. At the moment of relapse all sera revealed inhibitory activity towards PR3-alpha1AT complexation (median 22%, range 10-59%). Disease activity score (r=0.87, P