Pure T-cell Mediated Rejection Following Kidney Transplant According to Response to Treatment 

Abstract

Over the last two decades, the focus of studies on graft survival (GS) after kidney transplantation (KT) has largely shifted from T-cell mediated rejection (TCMR) to antibody-mediated rejection (ABMR). However, there are still cases of pure acute TCMR in histological reports, even after a long time following transplant. We thus evaluated the impact of pure TCMR on GS according to treatment response. We also performed molecular diagnosis using a molecular microscope diagnostic system (MMDx) to determine the accuracy of the histologic diagnosis of pure TCMR. A total of 63 patients were included in our study and divided into non-responders (N = 22) and responders (N = 44) according to their response to rejection treatment. Molecular diagnosis and histologic diagnosis were conducted simultaneously on a separate group of 23 patients. The non-responders had a significantly longer duration between treatment and recurrent rejection than did the responders (24 vs. 11 months; P < 0.01). The cumulative incidence of recurrent rejection after treatment was significantly higher in the non-responders as well (64% vs. 29%; P < 0.01). Non-response to rejection treatment was significantly associated with the following factors: GFR at biopsy, ΔGFR (baseline GFR – GFR at biopsy), TCMR within one year, t score, and IF/TA score. We also found that non-responder vs. responder (HR = 3.31; P = 0.04) and lower GFR at biopsy per 10 mL/min/1.73m2 (HR = 0.56; P = 0.03) were independent risk factors of graft failure. The responders had a significantly superior overall GS rate compared with the non-responders (P < 0.01). Molecular assessment using MMDx showed a good correlation with histologic diagnosis in ABMR, but not in TCMR. Solitary TCMR was a significant risk factor of graft failure in patients who did not respond to rejection treatment. Molecular assessment using MMDx did not show a good correlation with histologic diagnosis in TCMR, suggesting that acute pure TCMR at one year after transplant in histologic reports should be interpreted with caution.