Absence of anti-neutrophil cytoplasmic antibody (ANCA) in Henoch-Schönlein purpura and immunoglobulin A nephropathy

We have studied the presence of anti-neutrophil cytoplasmic antibodies (ANCA) in 16 patients with Henoch-Schonlein purpura (HSP) and 10 patients with immunoglobulin A nephropathy (IgAN). An indirect immunofluorescence test using ethanol-fixed neutrophils as a source of antigen and an enzyme-linked immunosorbent assay using purified proteinase-3 and myeloperoxidase as antigens were used. Neither immunoglobulin G nor immunoglobulin A (IgA) ANCA were found in any of the patients studied. It was shown that fluorescein-isothiocyanate conjugated anti-human IgA antibodies bound to ethanol-fixed normal human neutrophils non-specifically, suggesting the possibility that false positive staining was responsible for the previous reports. We conclude that ANCA does not play an important role in the pathogenesis of HSP and IgAN.