Isolation and characterization of nephritogenic antigen from bovine glomerular basement membrane

A method for isolation of a potent nephritogenic antigen from bovine glomerular basement membrane has been established; the glomerular basement membrane was solubilized by trypsin digestion and fractionated successively by gel filtration on Ultrogel AcA-34, concanavalin A affinity chromatography and affinity chromatography on immobilized antibodies. The antigen thus prepared was found to be highly nephritogenic; it causes glomerulonephritis in rats by a single injection of 0.1 mg per individual. Amino acid and carbohydrate analyses revealed that the antigen is a glycoprotein which contains amino acids and sugars characteristic of collagen, namely, hydroxyproline, hydroxylysine, glycine, glucose and galactose, although the relative amounts of these amino acids and sugars are less than those found in Type IV collagen of glomerular basement membrane.