OR6 Successful deceased donor kidney transplantation of highly sensitized candidates across positive cross match and strong donor-specific HLA-DP antibodies without desensitization

Abstract

Aim Over 50% of kidney transplant (Ktx) candidates with 100% CPRA display HLA-DP antibodies, which impair the chances of finding a compatible deceased donor (DD) despite national sharing. Herein, we assessed the impact of donor-specific HLA-DP antibodies (DP-DSA) on Ktx outcome. Methods DD Ktxs performed at UCSF (n = 569) from 2013 to 16 were analyzed. Based on pre-tx DSA status, recipients were divided into 3 groups: DSA −ve (n = 465), non-DP DSA +ve (n = 81), and DP-DSA +ve (n = 23). All recipients received standard immunosuppression, and DP-DSA +ve recipients received additional 1 dose IVIG at day-1 post-tx. Grafts were evaluated by 6 mo protocol biopsies (Bx) and cause Bx. HLA antibodies were tested using single antigen bead assay (One Lambda). Results There were more highly sensitized patients (CPRA > 97%) and well-matched Ktx in DP-DSA +ve group compared to the other 2 groups (Table). All recipients in DSA −ve and non-DP DSA +ve groups had a −ve T and B cell pronase flow-crossmatch (FXM), while 30% (n = 7) of DP-DSA +ve group that had a DP-DSA of >10,000 MFI, displayed a +ve B-FXM (MCS ∼ 200; 120 cutoff). There were no hyper acute rejection episodes in all 3 groups. The DP-DSAs were self-decayed overtime post-tx in all 23 recipients transplanted with pre-formed DP-DSAs (Figure). The Bx findings revealed no significant difference in the rate of antibody-mediated rejection (ABMR) or in acute cellular rejection (ACR) between the 3 groups. Two recipients transplanted with DP-DSAs but −ve XMs lost their grafts: one was a 46F re-tx recipient with 100% CPRA, 1/12 HLA-mismatch, DP4 DSA (MFI = 6956), lost due to ACR in 4 months; another was 62 M, 19% CPRA, 7/12 HLA-mismatch, DP1 DSA (MFI = 4165), suffered Polyomavirus nephropathy at 5 months. Conclusions Kidneys can be transplanted across DP-DSAs with no apparent effect on graft survival. This strategy increases the DD Ktx in highly sensitized patients without pre-tx desensitization. The long-term outcome studies are ongoing.