[Antineutrophil cytoplasmic antibodies: a new diagnostic tool].

Two main types of antineutrophil cytoplasmic antibodies (ANCA) have been recognized by indirect immunofluorescence. ANCA-D are defined by diffuse fluorescence and are directed against proteinase 3. They are highly specific for Wegener's granulomatosis, and their titre varies with disease activity. ANCA-P are responsible for perinuclear fluorescence and are principally found in other types of vasculitis and in idiopathic crescentic glomerulonephritis. In patients with suggestive clinical signs, ANCA are of considerable diagnostic value when specific histology is difficult to obtain. Therapeutic monitoring and prevention of Wegener's disease relapses could rely on regular measurements of ANCA titres. Moreover, studies on the pathogenetic role of ANCA may transform current physiopathological concepts and nosology of vasculitis.