Localization of antiglomerular basement membrane-binding polyclonal antibodies in rat lung and kidney using post-embedding immunogold electron microscopy.

Post-embedding immunogold electron microscopy (IAuEM) techniques utilizing low-temperature embedding in Lowicryl K4m and LR White resin were used to localize the binding sites of two sheep anti-rat glomerular basement membrane polyclonal antibodies (P1 and P2) and a sheep anti-rat lung antigen antibody. P1 localization was bilaminar in a linear pattern along the subepithelial and particularly the subendothelial aspect of the glomerular basement membrane. P2 was bound diffusely throughout the lamina densa, even at supramaximal doses. The anti-lung antibody bound in an interrupted linear pattern throughout the lung basement membrane (alveolar and capillary), and showed an intense, diffuse binding to the glomerular basement membrane. IAuEM allowed definition of the precise basement membrane binding sites of these polyclonal reagents.