Anti-Neutrophil Cytoplasmic Antibodies (ANCA) in Wegener's Granulomatosis

Sir, Since we submitted our editorial on the Enigma of Wegener's Granulomatosis (1), further data on the role of the anti-neutrophil cytoplasmic antibodies in the diagnosis and pathogenesis of the vasculitis of WG has become available. Falk and Jennette (2) have shown that this antibody is present in significant quantity in the serum of patients with microscopic polyarteritis nodosa and idiopathic necrotising and crescentic glomerulonephritis, thus diluting the impact of this test in the confirmation of WG. The useful, ness of ANCA in the follow-up of patients has also been clearly established (2). Whereas Lockwood et al. had suggested that ANCA had specificity for a small polypeptide found on alkaline phosphatase (3), Falk and Jennette have shown that there are at least two types which can be differentiated by their reaction with myeloperoxidase (2). These Authors have further supported our speculatlon that neutrophil activation