Rapidly progressive glomerulonephritis. Combined antiglomerular basement membrane antibody and immune complex pathogenesis.

We present the clinical and pathologic data from two patients with rapidly progressive glomerulonephritis in whom the unusual combination of antiglomerular basement membrane antibody and immune complex disease was observed. In both patients the diagnosis of antiglomerular basement membrane disease was confirmed by renal tissue immunofluorescence and by positive assays for circulating antiglomerular basement membrane antibody. Ultrastructural studies revealed membranous nephropathy in one patient. Our data from this patient suggested evolution of pre-existing membranous nephropathy into antiglomerular basement membrane disease. In the second patient electron microscopy of renal tissue demonstrated numerous subendothelial, mesangial, and subepithelial deposits. It was impossible to ascertain in this patient whether antiglomerular basement membrane antibody or immune complex mediated injury was the primary pathogenetic event. Our data provide additional evidence for the rare clinical appearance of concurrent antiglomerular basement membrane and immune complex disease. Although the coexistence in both patients of antiglomerular basement membrane disease with immune complexes may have been coincidental, we think that this is unlikely. Rather our data suggest that the two mechanisms are causally related and that either one could have been the primary disease process.