Rosa Ayala, Inmaculada Rapado, Antonio Perez, Silvia Grande, Alicia Arenas, Alvaro García Sesma, Jose Luis Vicario, Manuel Serrano, Jose Angel Martinez, Santiago Barrio, Carmelo Loinaz, Carlos Jimenez, Enrique Moreno and Joaquin Martinez-Lopez
Background: The aim of the study is to design a predictive model of graft rejection in liver transplant recipients based on donor chimerism (DC) quantification, functional study of Natural Killer cells and cytokine levels.
Methods: Seventy-four liver transplant recipients and their respective donors were studied, providing a total of 468 post-transplantation samples in the chimerism study. A total of 23 Liver Transplant patients and their respective donors took part in HLA typing and KIR genotyping, phenotyping, and cytotoxicity studies. 62 liver transplant recipients were analyzed in this cytokine study (62 pre-transplant and 109 post-transplant serum samples). Chimerism study was carried out by quantitative real time PCRs and 7 indels and 14 SNPs were detected with TM probes. A study of NK-cell subsets was performed on fresh samples by multiparametric flow cytometry (Becton Dickinson). KIR genotyping and KIR ligand were analyzed by PCR with a KIR typing Kit (Milteny Biotec). Cytotoxicity assays were monitored in a conventional 2-hour europium-TDA release assay (Perkin-Elmer). Biorad “17-plex Kit on a luminex” platform was used for cytokines measurement.
Results and conclusions: High chimerism levels during the first months after transplantation were related to a lower probability of rejection. A CD56 bright NK cell subset appeared to dominate the early post-transplant period following liver transplantation. A tendency to high frequency of graft rejection was observed in cases with KIR-ligand mismatches. Donors lacking C1 ligands exhibited increased risk of acute rejection. Cytokine levels predicted events in liver transplant recipients: low TNFα levels in pre-transplant recipient samples were associated with liver disease relapse and low IL17 and TNFα levels and high GMCSF and IL1β levels were associated with low rejection free survival. Finally IL6 levels showed an adverse impact on recipient overall survival.