P109 Preliminary identification of immune cells in the perfusate of renal allografts undergoing hypothermic machine perfusion

Abstract

Aim Renal allografts stored with hypothermic machine perfusion (HPM) have improved outcomes compared to static methods. Passenger immune cells from the allograft have been implicated in acute rejection; improved outcomes with HPM may be due to cell removal by the pump. This study aimed to identify passenger immune cells present in the perfusate of HPM-preserved allografts. Once characterized, future strategies to suppress these cells may prevent acute rejection and improve graft survival. Methods All kidneys placed on HPM prior to transplant from May 2016 to August 2017 were eligible. Perfusate fluid was analyzed using flow cytometry for immune cells and information about the donors was collected. Wilcoxon Scores and Spearman Correlation Coefficient were used in statistical analysis. Results Twenty-seven perfusate specimens were analyzed. Selected donor characteristics: 63.6% male, 36.4% female; 63.6% donation after cardiac death; 54.5% pre-procurement transfusion. The mean HPM and cold ischemia times (CIT) were 9.9 h and 13.9 h respectively, and mean KDPI 36%. Flow cytometry showed a heterogeneous mix of immune cell types in the perfusate, similar to blood. CD15+ granulocytes, CD14+ monocytes, and CD8+ T cells were predominant in the perfusate. Dendritic and natural killer (NK) cells in perfusate were more abundant compared to blood. Conclusions Passenger immune cells, specifically dendritic cells have been implicated in acute rejection. This study showed the perfusate of renal allografts contains an array of immune cells, with a significantly higher percentage of dendritic cells and NK cells, as compared to blood. Future studies would show if HPM removal of these immune cells accounts for improved outcomes. ∗Frequencies of Cell Types in Human Peripheral Blood, www.stemcell.com .