[Anti-cytoplasm antibodies to polynuclear neutrophils: specificity in renal vasculitis]

We present a retrospective study of all patients with a positive anti-neutrophil cytoplasm autoantibodies (ANCA) result from July 1987 to December 1990. The aims of the study were to assess specificity of ANCA in renal vasculitis and to correlate ANCA immunofluorescence subtypes with clinical aspect, diagnosis, severity and outcome. Anti-myeloperoxidase antibody (A-MPO) was sought in 31 cases. Specificity was 86% and false-positive results were 11%. ANCA subtypes varied with the clinical picture. C-ANCA were more often present when renal vasculitis was associated with pulmonary and ear, nose and throat involvement; P-ANCA were more often present when there was no respiratory tract involvement. Thus C-ANCA were preferentially associated with Wegener's granulomatosis and P-ANCA with microscopic polyarteritis and pauci-immune necrotizing and crescentic glomerulonephritis. No correlation was found between ANCA subtypes and severity or outcome. A-MPO were positive in 14 cases (especially in micropolyarteritis and necrotizing glomerulonephritis).