Associations Between Pre-Transplantation T Cell Populations and Acute Cellular Rejection Post-Liver Transplantation-Results From a Prospective Cohort Study.

Acute cellular rejection (ACR) remains a common complication post-liver transplantation despite standardised immunosuppressive regimens. Identifying patients at high risk of ACR is challenging, and new tools for prediction are needed. This study aimed to investigate if proportions of circulating T cells as well as different stages of maturation, exhaustion, and activation of T cells pre-transplantation are associated with ACR in liver transplant recipients within the first year post-transplantation. In the prospective ImmuneMO:SOT cohort study, we recruited participants listed for liver transplantation at Copenhagen University Hospital-Rigshospitalet who subsequently underwent liver transplantation. Before transplantation, we collected blood for extensive immune cell profiling using the standardised DURAClone flow cytometry panel and investigated if proportions of CD4⁺ and CD8⁺ T cells, including Th17, Treg, and memory T cell subsets, as well as their activation and exhaustion states were associated with ACR within 1 year post-transplantation. We included 40 liver transplant recipients, of whom 60% were male and had a median age of 50 years. ACR occurred in 37.5% of liver transplant recipients. We found no associations between investigated proportions of T cell subsets, including CD4⁺ (p = 0.25), CD8⁺ (p = 0.43), Th17 (p = 0.61), or Treg cells (p = 0.54) and ACR. This was consistent across activated and exhausted T cells as well as memory T cell subsets. Our findings suggest that proportions of pre-transplant circulating T cells have limited predictive value for post-transplantation ACR. Investigating if other circulating immune cell populations pre-transplantation are associated with ACR after liver transplantation is warranted.