PATHOLOGICAL RELEASE OF URINARY ENDOPEPTIDASE 2411 EARLY AFTER RENAL-TRANSPLANTATION

Endopeptidase 24.11 (EC 3.4.24.11) enzymatic activity was spectrofluor imetrically measured in human urine, using a synthetic peptidic substr ate. Urinary endopeptidase 24.11 output (U(endo)) was determined in 24 -hour urine samples of 10 kidney transplant recipients during the firs t 2 weeks after surgery. In 9 patients, a large increase in U(endo) le vels was noted during the 1st and/or the 2nd postoperative days (mean +/- SEM of peak U(endo) 624 +/- 122 mug/24 h, p = 0.0003 as compared t o 239 +/- 20 mug/24 h in a healthy control population). This occurred whether patients received OKT3 (n = 6) or cyclosporine A (n = 3) as pr imary immunosuppression. U(endo) returned to normal between the 3rd an d the 5th postoperative day. We conclude that renal transplantation is associated with an early and marked release of endopeptidase 24.11 in urine. This could be due to the potentially toxic effects of ischemia and/or immunosuppressive drugs on the proximal tubular epithelium. Th e clinical usefulness of urinary endopeptidase 24.11 as a marker of tu bular injury remains to be assessed.