Urinary lysosomal enzymes for detection of acute renal allograft rejection

Six patients who received renal transplants were closely monitored to compare the sensitivity of urine levels of beta-galactosidase and N-acetyl-beta-glucosaminidase with conventional clinical and laboratory parameters in the detection of impending rejection. A rapid (60 minute), simple, accurate fluorometric assay was used to measure activities of both enzymes. Eighty per cent of ten rejection episodes were accompanied by a two- to sixfold increase in enzyme release. Parallel changes in serum creatinine levels and urinary volume occurred in six rejection episodes, but in two episodes, elevated urinary enzyme levels were observed two and four days prior to clinical evidence of rejection. It is concluded that urinary lysosomal enzyme measurements by fluorometric assay are valuable indicators of acute renal rejection, particularly when the diagnosis is not clearly established by conventional criteria that show only minimal changes. Continuing studies in a large group of renal transplant recipients are under way to evaluate the validity of this conclusion and to determine whether enzyme measurements, will, indeed, be indicative of early rejection.