Concurrent Antiglomerular Basement Membrane Antibody and Immune Complex Mediated Glomerulonephritis

A teenage male, with Goodpasture's syndrome and serum antiglomerular basement membrane (anti-GBM) antibodies, had a focal proliferative glomerulonephritis with crescents. Immunofluorescence microscopy of his glomeruli using anti-IgG antibodies demonstrated both intense linear GBM staining, and granular subepithelial staining. Electron microscopy revealed numerous subepithelial electron-dense deposits. Identical IgG subclass restriction (dominance of IgG1 and IgG4) of both types of glomerular deposits in this patient supports, but does not prove, a postulate that the linear staining was due to anti-GBM antibodies bound to intact GBM, and that the granular staining was due to anti-GBM antibodies complexed with freed GBM antigens.