Peripheral blood catalase in patients undergoing renal transplantation

Oxygen free radicals are mediators of tissue injury and catalase is an enzyme which is involved in limiting this process. We examined peripheral blood catalase activity (PBCA) to assess its value as a marker in detecting tissue injury related to renal allograft rejection. Thirty-one consecutive recipients of kidney (n = 29) or simultaneous kidney/pancreas (n = 2) transplants and 10 normal volunteers were studied. Catalase activity, measured by the disk-flotation method, was expressed as Sigma units X 10(-3)/ml (SU/ml) of whole blood. Normal PBCA was determined to be greater than 76 SU/ml. Twenty-nine episodes of renal allograft rejection (diagnosed by clinical criteria +/- biopsy [79%]) were observed in 26 patients. PBCA (mean +/- SEM) was found to be low (64 +/- 1 SU/ml) in 28/29 episodes (chi 2 = 46.3, P less than 0.001), and the decrease (at least two consecutive daily catalase values less than 76 SU/ml) occurred 2 days prior to the clinical/biopsy diagnosis of rejection in 26/28 episodes. The sensitivity of PBCA as a discriminant of rejection was 97%, specificity was 96%, and test accuracy was 96%. PBCA less than 50 SU/ml on two or more occasions occurred in five cases and transplant nephrectomy was required in four of these because of uncontrollable rejection. Nine episodes of cyclosporine nephrotoxicity occurred in 7 patients and none of these episodes was associated with a decreased PBCA. Our data suggest that decreased PBCA is a sensitive and specific indicator of renal allograft rejection. PBCA remains normal during episodes of cyclosporine nephrotoxicity and therefore provides a rapid and inexpensive discriminant from allograft rejection.