Autoantibodies to neutrophil cytoplasmic antigens in systemic vasculitis have the same target specificity

Many patients with systemic vasculitis have antibodies to neutrophil cytoplasm antigens (ANCA) detectable by indirect immunofluorescence. We sought to characterize further the nature of these antigens. Western blots of neutrophil protein extracts indicated that nine patients' sera, positive for ANCA by immunofluorescence, all reacted with a 45 kDa and a 27-31 kDa protein. Negative control sera, and sera taken in remission, did not react with either of these antigens. The results suggest that ANCA in vasculitis have the same target specificity and may therefore permit greater accuracy of diagnosis and increase our understanding of the pathogenesis of the conditions.