IgA antineutrophil cytoplasmic antibodies in cutaneous vasculitis

Background Antineutrophil cytoplasmic antibodies (ANCA) of the IgA isotype have, for the most part, been detected in patients with Henoch-Schonlein pu rpura (HSP) or inflammatory bowel disease. Objectives We have evaluated the prevalence of IgA ANCA in a series of patients with different causes of cu taneous vasculitis. Methods Forty consecutive patients with histologically proven leucocytoclastic vasculitis were included in the study: 18 had syste mic vasculitis as well as cutaneous lesions, 10 of whom were diagnosed as h aving HSP, and 22 had only cutaneous vasculitis (with no identified cause i n 10 cases). IgA ANCA were sought by indirect immunofluorescence using etha nol-fixed human neutrophil preparations as the substrate. Results IgA ANCA were detected in six of 40 patients (15%) (one each with HSP, ulcerative co litis, Sjogren's syndrome, hypergammaglobulinaemia associated with Castelma n's disease, erythema elevatum diutinum and bacterial endocarditis). Three of these patients also had IgG ANCA whose target antigen remained unidentif ied. Conclusions IgA ANCA are rarely observed in HSP (10%) and can be detec ted in a wide variety of other cutaneous vasculitides.