Anti-myeloperoxidase antibodies in systemic vasculitis.

Anti-neutrophil cytoplasmic antibodies (ANCA) are important diagnostic markers in vasculitic disorders. In a study of 164 patients with various clinical syndromes associated with vasculitis, 60 were found to have the antibody, as detected by indirect immunofluorescence; 23 had the so-called perinuclear antibody pattern, and of these, 15 had antibodies to neutrophil myeloperoxidase in an ELISA. These patients had multi-system involvement, and 14 of the 15 had histological evidence of small-vessel arteritis in the kidneys. In preliminary experiments, the isolated IgG from one patient was shown to inhibit luminol-dependent chemiluminescence of fluid phase myeloperoxidase.