Anti-glomerular basement membrane disease mediated by IgG and IgA: a case report.

Background: Anti-glomerular basement membrane (anti-GBM) disease is a rare autoimmune condition responsible for rapidly progressive glomerulonephritis. This disease is usually mediated by IgG autoantibodies against the noncollagenous domain of the α3(IV) collagen chain. In rare cases, IgA or IgM anti-GBM antibodies are involved. This raises the question of whether there are different types of antibody-mediated anti-GBM disease at the same time.

Case Report: A 37-year-old woman with anti-GBM disease mediated by IgG and IgA. The patient developed rapidly progressive glomerulonephritis with nephrotic syndrome. Indirect immunofluorescence analysis indicated the presence of IgG and IgA antibodies reactive with a basement membrane component, identified by enzyme-linked immunoadsorbent assay and Western blotting as the α3(IV) collagen chain. After plasmapheresis and immunotherapy (steroids and cyclophosphamide), much improved the massive proteinuria and renal function. Follow up to date, she had normal renal function without proteinuria.

Conclusions: This is the first case report of anti-GBM disease mediated by IgG and IgA. If the clinical presentation and histopathological findings are suggestive of atypical anti-GBM disease, alternative laboratory tests such as Western blotting analysis can be used to confirm the diagnosis.