P157 Virtual crossmatch can be used successfully as pre-transplant crossmatch for most deceased donor transplants at a high volume center

Abstract

Aim We developed a reliable virtual crossmatch (VXM) method for use as pre-transplant XM for deceased donor (DD) kidney transplantation (Ktx). Here we report the outcomes of 248 Ktx performed based on VXM. Methods Our VXM method includes 3 integral processes: accurate identification of HLA antibodies (Ab) using right tools and principles, assessment of correlation between the strength of donor specific Ab (DSA) and T and B cell bindings by flow XM (FXM), and listing of clinically relevant unacceptable antigens that will not impact DD offers or graft survival. From the start of the new KAS through Dec. 2016, 434 DD-Ktx were performed at UCSF, of which 375 (86%) were performed based on VXM (350 were VXM−ve with DSA+/− and 25 were VXM+ve with DP/DQα DSA+). 59/434 (14%) of the Ktxs were performed based on pre-tx FXM (54 were FXM−ve with DSA+/− and 5 were FXM+ve with DP-DSA+). Six month protocol biopsy (Bx) and cause Bx were evaluated for C4d rejection. Results All 350 pre-tx VXM−ve assessments were negative by retrospective FXM. There were no hyper acute rejections in these 350 Ktx. Biopsies of 273 negative VXM-based Ktx revealed no significant difference in the rate of antibody-mediated rejection (ABMR) or in acute cellular rejection (ACR) between 3 distinct CPRA groups (Table). Females, re-tx, well-matched tx, and de nova DSA producers were more frequent in both high CPRA groups compared to 0–79% CPRA group. Pre-tx DSA was more common in 99–100% CPRA group compared to other groups. Conclusions Our VXM protocol is reliable, has excellent graft survival, and works even for those with 100% CPRA. Accurate VXM method improves organ allocation for broadly sensitized patients, increases the efficiency of regional/national sharing, and avoids reallocation into unintended recipients. Download : Download high-res image (137KB) Download : Download full-size image