Evaluation of proteinuria by two-dimensional polyacrylamide gel electrophoresis after kidney transplantation.

Urinary proteins were studied in patients after kidney transplantation during various functional states (normal function, acute rejection, chronic rejection) by two-dimensional polyacrylamide gel electrophoresis. In the first dimension, the proteins were separated according to their electric charge by isoelectric focusing, and in the second dimension according to their molecular weight by sodium dodecyl sulfate polyacrylamide gel electrophoresis. After electrophoresis the proteins were visualized using a highly sensitive silver stain technique. The combination of these methods allowed the discrimination of up to 250 protein spots in human urine, most of them unidentified up to now. Functional changes of the kidney transplants were accompanied by complex changes of the protein pattern in urine. These changes cannot be simply compared to the tubular and glomerular pattern of proteinuria which can be identified by one-dimensional sodium dodecyl sulfate electrophoresis. The 2D electrophoresis of urinary proteins may develop into a useful tool in localizing of kidney damage and in the evaluation of renal disease.