Ultrastructural localization and quantitation of nephritogenic antibodies in experimental glomerulonephritis

The recently developed postembedding immunoelectron microscopic technique using low temperature embedding in Lowicryl K4M has been applied for the localization and relative quantitation of nephritogenic antibodies in rats with nephrotoxic serum nephritis. Nephrotoxic serum nephritis with different degrees of severity was induced by intravenous administration of increasing doses of rabbit anti-rat glomerular basement membrane antiserum to male Wistar rats. Twenty-four hours after administration, renal tissue was processed for immunoelectron microscopy using Lowicryl embedding after fixation in paraformaldehyde. Thin sections were stained with colloidal gold-labeled antibodies to rabbit IgG. By morphometric analysis the amount of gold label per nanometer of glomerular basement membrane was counted and a strong correlation was found with the amount of administered antiserum. These data show that postembedding immunoelectron microscopy using low temperature embedding in Lowicryl K4M and immunogold staining can be applied to study the localization and relative quantitation of tissue-bound immunoglobulins.