A 59-kd Renal Antigen as a New Target for Rapidly Progressive Glomerulonephritis

Anti-glomerular basement membrane (anti-GBM) antibodies are the hallmark of anti-GBM disease, which is characterized by rapidly progressive glomerulonephritis. We describe the case of a 58-year-old woman who presented with rapidly progressive glomerulonephritis with typical anti-GBM staining found by means of direct immunofluorescence microscopy, associated with linear immunoglobin G deposits on tubules. Serum analysis showed circulating anti-tubular basement membrane antibodies, but failed to detect anti-GBM antibodies. Immunoblotting showed that serum antibodies reacted with a 59-kd antigen found along both the GBM and tubular basement membrane.