Background: CD4 CD25 Foxp3 regulatory T cells (Tregs) represent 5-10% of peripheral CD4 T cells and have been suggested to prevent acute graft rejection (AR). Our project was aimed to investigate the relation between the level of pre-transplant and post-transplant peripheral Tregs and the development of AR episodes in patients after kidney transplantation.
Material/Methods: The project included 44 patients undergoing kidney
transplantation. During the six-months period following the transplantation AR
was diagnosed in 11 patients. Peripheral blood samples were collected 1 day before and 10 days after the transplantation and cytometrically tested for concentrations of Tregs.
Results: The pre-transplant analysis showed significantly lower levels of peripheral Tregs in AR patients vs. control. A lower level of Tregs was also observed in NONAR patients vs. control, however, it was still higher than in the AR group. The 10-day post-transplantation analysis showed a similar pattern,
however, a significant increase in the concentration of Tregs in NONAR patients was observed, whereas no change was recorded in AR patients.
Conclusions: Lower pre-transplant levels of peripheral Tregs were found in both groups, AR and NONAR vs. control group. The deficiency of Tregs in patients with end-stage renal failure might be due to the long-term inflammatory processes adversely affecting the peripheral regulatory mechanisms, however significantly lower levels of Tregs observed in AR patients might also be related to genetic predispositions. Our observation suggests that the size and possibly the functionality of Tregs in AR group was not sufficient to successfully control the immune response after kidney transplantation leading to AR.

Keywords: Immunosuppression, Kidney Transplantation, Tissue typing