Circulating anti‐neutrophil cytoplasm antibodies in patients with rapidly progressive glomerulonephritis and extracapillary proliferation

. We investigated 39 patients with rapidly progressive glomerulonephritis and extracapillary proliferation for the presence of circulating anti-neutrophil cytoplasm antibodies (ANCA) by indirect immunoflourescence. Patients with antibodies against the glomerular basement membrane, systemic lupus erythematosus or with glomerulonephritis following infection and where renal disease could be ascribed to treatment with drugs were not included. IgG class ANCA producing diffuse cytoplasmic immunostaining were detected in 54% of the patients. With reservation for the difficulties involved in distinguishing between different forms of systemic vasculitis, these autoantibodies were present in patients with Wegener's granulomatosis (12 out of 17 patients), polyarteritis nodosa (4/6), idiopathic extracapillary glomerulonephritis (1/4), and with less distinct syndromes (4/10), but not in Henoch-Schonlein's purpura (0/2). Another 18% of the patients showed ‘granulocyte-specific anti-nuclear antibodies’ with perinuclear immunostaining. This pattern was recently reported to indicate the presence of antibody against myeloperoxidase of alcohol-fixed neutrophils. Autoimmune mechanisms, particularly those involving components of neutrophil granulocytes, could play a significant role in development of extracapillary glomerulonephritis.