Clinical and pathological manifestations of patients with antineutrophil cytoplasmic autoantibodies directed against proteinase 3 or myeloperoxidase.

OBJECTIVE

To compare the clinical and pathological manifestations of patients with antineutrophil cytoplasmic autoantibodies (ANCA) directed against proteinase 3 (anti-PR3) or myeloperoxidase (anti-MPO).

METHODS

One hundred and forty patients with ANCA were detected for anti-PR3 and anti-MPO by ELISA. The clinical features at presentation, histopathological characteristics and outcome of all patients who were tested positive for anti-PR3 or anti-MPO were analysed.

RESULTS

In anti-PR3 group (n = 21), 16 cases (76.2%) had systemic vasculitis, in which Wegener's granulomatosis prevailed (13 cases, 61.9%). In anti-MPO group (n = 31), 19 cases (61.3%) were diagnosed as systemic vasculitis and 12 cases (38.7%) as microscopic angiitis. For vasculitic patients with anti-PR3 and anti-MPO, the disease duration at diagnosis was 9.6 +/- 2.0 m and 4.4 +/- 0.9 m respectively, P < 0.05; vasculitis activity index (BVAS) and mean number of affected organ were 22.5 +/- 2.1, 5.0 +/- 0.4 and 25.1 +/- 1.7, 4.8 +/- 0.4 respectively, P > 0.05; upper respiratory tract, eye and joint involvements were 11(68.8%), 7(43.8%), 11(68.8%) and 7(36.8%), 2(10.5%), 5(26.3%) respectively, P < 0.05. Although there was no statistical difference in renal involvement between these two groups, patients with serum creatine > 500 micromol/L were more commonly seen in anti-MPO group than in anti-PR3 group, which were 8(42.1%) and 2(12.5%) respectively, P < 0.05. Ten relapses were seen in anti-PR3 group and only 2 in anti-MPO group, but the acute mortality rate in anti-MPO group (5/19, 27.4%) was much higher than that in anti-PR3 group (1/16, 6.3%).

CONCLUSIONS

Anti-PR3 and anti-MPO occurred mainly in systemic vasculitis. A large divergence was seen in the disease spectrum between patients with anti-PR3 and those with anti-MPO. In particular, upper respiratory tract, eye and joint involvements, granuloma formation and relapse were more prominent in anti-PR3 patients. By contrast, the anti-MPO patients had a more acute disease onset, more rapid progressive renal involvement and a higher acute mortality rate.