Monoclonal antibodies to human glomerular antigens. II. Using human adult kidney components as antigens

Using human kidney cortical homogenates and long-term cultured glomerular cells as antigens, the author produced three monoclonal antibodies to glomerular components; 25C reacted with the glomerular basement membrane (GBM) and the wall of blood vessels but with neither the tubular basement membrane (TBM) nor the Bowman's capsule, 33G reacted predominantly with the mesangium, and 34F reacted with glomeruli and the tubular brush border in a granular pattern. Both 25C and 33G exhibited the species-restricted property, and 34F reacted with glomeruli and tubular brush border of all the species examined. Overnight incubation of the kidney sections with 4.0 M urea revealed the reactivity of 25C to the TBM and Bowman's capsule. Dot immunobinding assay revealed that 25C did not react with the known extracellular matrices examined in this study, but rather with collagenase-digested GBM fraction. Also, 33G recognized fibronectin. Western blotting revealed the binding of 34F to the 145-kDa polypeptide solubilized from the kidney with 0.5 M NaCl, and also showed the binding of 25C to 210-kDa polypeptide of collagenase-digested GBM. These findings revealed structural variations in the basement membrane and the existence of a common antigen between the glomeruli and tubular brush border in the human kidney.