Proteinuria after renal transplantation: diagnosis with highly sensitive silver stain in sodium dodecylsulphate-polyacrylamide gradient gel electrophoresis.

Sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of urinary proteins is becoming increasingly significant in monitoring renal allograft recipients. After conventional Coomassie Blue staining, changes in renal proteinuric patterns during acute renal transplant rejection could not be seen in many cases. Discrimination between rejection and nephrotoxic side effects of cyclosporine overdosage was also not possible. We therefore examined the possible advantages of a highly sensitive silver staining technique in this study. A total of 734 urine samples obtained from 38 patients after allogenic kidney transplantation were examined by SDS-PAGE with consecutive Coomassie Blue and silver staining. Twenty-two histologically proven rejections and 20 cyclosporine overdosage episodes were diagnosed in these patients within a time period of up to 524 days after transplantation. No changes in proteinuric patterns were seen in 9 of 22 patients after Coomassie stain during rejection, and only 12 cases showed a rise of glomerular protein bands, whereas silver stain revealed an increase in 19 of 22 cases. Discrimination between cyclosporine overdosage and rejection was possible with a probability of p less than 0.001 after silver stain when using the changes in the number of glomerular protein bands as a criterion. These findings suggest that application of a highly sensitive silver stain instead of the conventional Coomassie stain after SDS-PAGE reflects considerable progress in monitoring renal allograft recipients.