Anti-Donor Regulatory T-Cell Therapy in Adult-to-Adult Living Donor Liver Transplantation: A Case Report

We report on the case of a 50-year-old female patient with symptomatic polycystic liver disease who underwent living donor liver transplantation (LDLT) using right liver graft from her ABO-identical husband. To achieve operational tolerance, regulatory T-cell (T-reg)-based cell therapy was applied, following the protocol introduced by Todo et al. Briefly, donor lymphocytes were collected by leukapheresis 20 days before LDLT without any adverse events, and the cells were irradiated with a dose of 30 Gy and kept frozen. Lymphopheresis of the recipient was conducted in a similar manner 1 day before LDLT, and donor cells and recipient cells were cultured with anti-CD80/86 antibodies to induce the donor-specific T-reg. At 14 days of culture, the CD4⁺CD25⁺Foxp3⁺ cells had increased from 1.51% to 5.21%, and mixed lymphocyte reaction assay using an intracellular fluorescent dye carboxyfluorescein diacetate succinimidyl ester-labeling technique revealed donor-specific hyporesponsiveness of CD4-positive lymphocytes. On postoperative day (POD) 13 (14 days of culture), these cells were infused to the recipient intravenously without any adverse events. Initial immunosuppression consisted of tacrolimus, steroid and mycophenolate mofetil (MMF), and cyclophosphamide (40 mg/kg) administered on POD 5. Both the steroid and MMF were continued until 4 weeks after LDLT, and the patient was discharged on POD 30 with normal liver function. On POD 52, the patient developed acute cellular rejection and received appropriate reinforcement of immunosuppressive therapy and is currently doing well with normal liver function 30 months after LDLT with reduced anti-donor allo-activity. In summary, T-reg therapy was safely performed in adult LDLT, and we are following the patient carefully to determine whether she can achieve operational tolerance in the future.