Physicochemical characteristics of glomerular basement membrane antigens in urine

Biochemical analysis of glomerular basement membrane (GBM), first isolated by Krakower and Greenspoon [1], has shown that it is composed of collagen linked to glycoprotein [2]. In 1968, Hawkins and Cochrane reported that nephritic rabbits excreted into their urine material antigenically related to GBM [3], Lerner and Dixon similarly found small amounts of it in the urine of normal rabbits [4], and McPhaul and Dixon detected it in normal human urine and showed it to be glycoprotein [5]. Urinary excretion of this GBM-related material, now generally called GBM antigens, is increased in various experimental [6–9] and human glomerular diseases [10–14]. Furthermore, physicochemically different GBM antigens have been observed in the urine of nephritic rabbits [3, 8, 9] and in pathologic human urine [14, 15].We have used gel filtration and ion-exchange chromatographic procedures to fractionate and to characterize the GBM antigens present in normal and pathologic human urine. We were especially interested in studying the urinary GBM antigens of children with congenital nephrotic syndrome of Finnish type (CNF), because it has been suggested that synthesis of GBM is abnormal in this disease [16]