Granzyme B Level in Acute Renal Transplant Rejection

Introduction: Acute rejection of renal transplant is a serious and common systemic inflammatory disorder which leads to decreasing half-life of transplant organ. Current diagnoses method is an invasive biopsy procedure on allogtraft kidney. Therefore, applying a novel and noninvasive diagnostic method such as Granzym B level in acute renal transplantation could help patients and improves survival of transplanted tissue.

Materials and Methods: This study was an analytical descriptive one in which 32 patients, who underwent kidney transplantation from May to August 2003 in Uremia - Iran were studied. Five sequential blood samples from each patient between day 2 and day 20 after renal transplantation were obtained continuously. Serum levels of granzyme B were measured using immunoassay method. In addition, in case of uncertain acute rejection, needle biopsies of kidney were performed. Patients were followed up to 9 - 12 months to control function of transplanted tissue.

Results: It was shown that 13 patients (40.5 %) with mean age of 33 years and 18 months duration of hemodialysis showed stable function of transplanted tissue. The mean serum levels of granzyme B in these patients were 148+ unit/ml. 19 patients (59.9 %), mean age of 43.74 years and mean hemodialysis duration 27 months, showed unstable function of transplanted tissue.  6 patients (19%) showed acute transplant rejection and 13 patients showed other etiological reaction. The mean serum levels of granzyme B in acute rejection in the first sample was 250.20 + 46.25 units/ml (day 2-5) in the second sample was 286.50+49.92 units/m (day 6-8), in the third sample was 275.60+68.40 units/ml (day 9-11) and in the forth sample was 253.17+86.14 units/ml (day 12-16). In relation to other two groups, the difference was statistically significant (p< 0.05). The mean serum levels of granzyme B in acute rejection group, in the fifth sample was 158.17+29 units/ml (day 17-20), and there was no statistical significant difference between two groups.

Conclusion: The study confirmed that continuous measurement of granzyme B   in whole blood by immunoassay methods within three weeks after renal transplantation could be a rapid and noninvasive diagnostic method for renal transplant rejection evaluation. Significant decrease of granzyme B at the end of third week after transplantation and after treatment with anti-acute rejection medicines could be helpful to evaluate response to anti-rejection treatment of transplantation. In conclusions, measurement granzyme B offers a noninvasive diagnosing acute^{rejection of renal allografts.}