Antineutrophil cytoplasmic antibody--a useful serological marker for vasculitis

Systemic necrotizing vasculitides, including polyarteritis nodosa, Churg-Strauss syndrome, "overlap" systemic vasculitis, Wegener's granulomatosis, and idiopathic crescentic glomerulonephritis, are frequent clinical diagnostic problems. These diseases have diverse presentations and are often rapidly progressive, causing irreversible injury to the vessels of the kidneys and lungs before effective immunosuppressive therapy is instituted. Even in their less fulminant forms, they are a cause of significant morbidity and mortality. Antineutrophil cytoplasmic antibody, a recently identified autoantibody, has a high sensitivity and specificity for this spectrum of diseases. The clinical and pathological similarities, the high frequency of antineutrophil cytoplasmic antibody expression, and the similar good response to immunosuppressive therapy suggest that these diseases may be linked by a common pathophysiological mechanisms. Evidence is growing that antineutrophil cytoplasmic antibody plays a central role in this mechanisms. A revision in the classification scheme of vasculitides to recognize that the polyarteritis group (polyarteritis nodosa, Churg-Strauss syndrome, and "overlap" systemic vasculitis), Wegener's granulomatosis, and idiopathic crescentic glomerulonephritis are closely related diseases may be warranted. The clinical and pathological features of systemic necrotizing vasculitides and the current knowledge concerning antineutrophil cytoplasmic antibodies are reviewed.