Objective  To discuss the relationship between Foxp3⁺regulatory T cell(Treg) and tumor recurrence of patients after liver transplantation for primary hepatocellular carcinoma (HCC) over University of California, San Francisco (UCSF) criteria.

  Methods  Clinical data of 24 patients with HCC undergoing liver transplantation in the Organ Transplantation Research Institute of the 309^th Hospital of People's Liberation Army from January 2010 to December 2013 were retrospectively studied. During the follow-up, 4 patients recurred (tumor recurrence group) and other 20 patients did not recur (tumor non-recurrence group). The blood samples of healthy people was selected as control group at the same period. The levels of alpha-fetoprotein (AFP) were compared at different time points of the recurrence group and the non-recurrent group before and after transplantation. The levels of Foxp3⁺Treg (Foxp3⁺Treg%) were compared at different time points of the tumor recurrence group, the tumor non-recurrence group and the control group before and after transplantation. The relations between expression of Foxp3⁺Treg and the levels of AFP, CD3⁺ and CD8⁺T before and after transplantation were analyzed by correlation analysis.

  Results  Compared with the level of Foxp3⁺Treg before transplantation and the normal level, the expression of Foxp3⁺Treg of patients in tumor non-recurrence group after transplantation firstly decreased, then gradually increased and finally stabilized at a low level. Compared with patients in tumor non-recurrence group, the levels of AFP and Foxp3⁺Treg of patients in tumor recurrence group increased obviously and were significantly higher than the normal levels (both in P < 0.01). Moreover, abnormal increase of Foxp3⁺Treg at early stage was prior to AFP among the patients in tumor recurrence group. Correlation analysis indicated that the change of Foxp3⁺Treg was consistent with the changes of AFP, which was positively correlated (P < 0.01). But the change of Foxp3⁺Treg was contrary to the change of effector T cells (CD3⁺T cells and CD8⁺ T cells), which was negatively correlated (P < 0.05-0.01). It indicated that Foxp3⁺Treg was closely associated with tumor recurrence after liver transplantation for HCC.

  Conclusions  Foxp3⁺Treg is closely associated with tumor recurrence after liver transplantation for HCC. In the patients after liver transplantation for HCC over UCSF criteria, the higher Foxp3⁺Treg is, the higher the recurrence risk is. Joint detection of AFP is beneficial to find tumor recurrence.