Assessing the adequacy of immunosuppression in pediatric liver transplantation with immune Monitoring: Are we there yet?

Current approaches used for pediatric liver transplant (LT) surveillance have diagnostic limitations. We used pleximmune™ immune reactivity index (IRI) and anti-HLA donor specific antibody (DSA) to predict the adequacy of immunosuppression (IS) relative to risk of acute cellular rejection (ACR) at 1-year post LT. This is a retrospective chart review of children who underwent LT between January 1, 2016, through December 31, 2020, and had at least one pleximmuneTM measurement performed within 60-days of a liver biopsy. There were 45 liver biopsies with accompanying pleximmuneTM in 31 children. An inverse correlation was observed between tacrolimus level and IRI (R = -0.34; p = 0.039). The sensitivity, specificity, positive and negative predictive values of IRI for diagnosis of ACR was 55 %, 65 %, 33 % and 81 % respectively. The combination of DSA and IRI had a specificity of 92 % and negative predictive value of 89 % for ACR. In conclusion, a high IRI identifies recipients with low tacrolimus levels. Thus, the associations observed in this non-standardized cohort support the use of pleximmuneTM IRI in combination with DSA, for hypothesis generation in future studies involving post liver transplant graft immune surveillance.