Objective: The unique mechanisms of immune regulation in the liver allow it to provide local and systemic immune tolerance to own and foreign antigens as a homeostatic condition via different T cell subsets and after liver transplantation (LT) while preserving an effective immune response against pathogens. Therefore, we aimed to analyze the Th17 and Treg subsets in the post-transplant period in patients with LT on immunosuppressive therapy and Treg/Th17 cell ratio and soluble CD30 (sCD30) as possible additional markers for characterizing the immune status of transplanted patients.

Patients and Methods: The study group consisted of 17 patients after LT on immunosuppressive therapy and 10 healthy controls. We assessed Th17 (CD3+CD4+CD183–CD194+CD196+CCR10–), Treg cells (CD3+CD4+CD25+CD127^-/low and CD4+CD25+ Foxp3+), Treg/Th17 ratio in peripheral blood by flow cytometry, and soluble CD30 (sCD30) in serum by ELISA.

Results: The mean percentage of T regs (mean ± SD% of CD4+cells) were 5.26±2.21 and 5.17±2.12, assessed by peripheral and cytoplasmic staining, respectively (p<0.0001, r=0.9588). LT patients showed significantly higher percentages of Th17 in peripheral blood than healthy controls (7.23% vs. 3.55%, resp.) and reduction in Treg - 5.26% vs. 7.82%, resp. (p<0.05). Treg/Th17 ratio in healthy controls averaged 2.31, while in the LT group, it was significantly lower - 0.73 (p<0.05). We also observed significantly higher sCD30 levels in patients 45.47±23.62 ng/ml compared to the healthy controls 15.63 ±5.69 ng/ml (p<0.05). No significant associations were found between the CD4+ subsets with serum CD30 levels were demonstrated.

Conclusions: This pilot study showed both reduced immune tolerance and increased activation of the immune system in LT patients compared to healthy controls. However, additional studies are needed to confirm and expand these results because the immune balance in our transplanted patients is a complex interaction between a tolerogenic liver, an immune response against liver graft and immunosuppressive therapy.