Graft immunologic events in deceased donor kidney transplant recipients with preformed HLA-donor specific antibodies.

INTRODUCTION

Pretransplant donor-specific HLA alloantibodies detected with the Single Antigen Bead (SAB) assay reflect an increased risk for acute antibody-mediated rejection (AMR). We herein report the incidence of both acute AMR and acute cellular rejection (ACR) during the first year posttransplantation, in a cohort of kidney transplant recipients (KTR) of deceased donor (DD) grafts, according to their DSA status. Pretransplant DSA do not preclude DD-KT in negative CDC-XM recipients at our center.

PATIENTS AND METHODS

246 KT were performed at our center between 01/2012 and 12/2015 and 100 KTR obtained from a DD were analyzed; 24% harbored DSA by SAB assay, MFI values >500 were considered positive. All recipients received thymoglobulin induction and generic tacrolimus-based maintenance therapy. Graft biopsies were performed by protocol on months 3 and 12 as well as per indication. The incidence of AMR and ACR was correlated with the existence of pretransplant DSA.

RESULTS

Overall, 34% of patients developed an acute rejection episode, 54.2% in the DSA group versus 27.6% in the non-DSA group (p=0.032), and most of these events were detected as subclinical conditions in protocol biopsies. AMR events developed in 33.3% and 19.7% (p=0.176) in the DSA and the non-DSA groups, respectively. ACR events were found in 16.6% and 6.6% (p=0.127) in the DSA and non-DSA groups, respectively. Graft function was similar between groups at the end of the 1st year posttransplant and no immunological graft loss occurred.

CONCLUSION

Despite the use of depleting induction therapy and adequate tacrolimus trough levels along with MMF and steroids, a high rate of rejection events was observed during the first year post-transplantation.