Antineutrophil cytoplasmic autoantibodies in patients with systemic sclerosis

Perinuclear type of antineutrophil cytoplasmic antibodies (p-ANCA) have been found in patients with periarteritis nodosa, Churg-Strauss arteritis, or pauci-immune idiopathic crescentic glomerulonephritis. Recently, the association of p-ANCA and normotensive renal failure, in patients with systemic sclerosis (SSc), was reported. We have studied the incidence of p-ANCA in patients with SSc and have investigated its relationship to clinical and laboratory findings. Sera from 77 patients with SSc were examined by the indirect immunofluorescence (IIF) test, employing an ethanol-fixed human neutrophil and enzyme-linked immunosorbent assay, using purified myeloperoxidase (MPO) as an antigen (MPO-ELISA). The sera from seven patients (9.1%) were p-ANCA positive, by both IIF and MPO-ELISA. One patient died from systemic necrotizing angiitis but the remaining six patients have shown no symptoms of systemic vasculitis or of renal involvement. There was a tendency for patients positive for p-ANCA (anti-MPO antibody) to also be positive for other autoantibodies, such as anti-Sc1-70 antibody, anti-centromere antibody, anti-microsome antibody, anti-thyroglobulin antibody and rheumatoid factor. Although the incidence of p-ANCA (anti-MPO antibody) is low in patients with SSc, and its clinical significance in SSc needs further investigations, this could be a serological marker for certain symptoms in SSc.