Different phenotypes of CD4CD25Foxp3 regulatory T cells in recipients post liver transplantation.

CD4 regulatory T cells (Tregs) play an important role in inducing immune tolerance in organ transplantation, which can be divided into CD45RATregs (resting Tregs, rTregs) and CD45ROTregs (activated Tregs, aTregs). Currently, the expressions and phenotypic changes of Tregs in recipients after liver transplantation (LT) is unknown. We therefore investigated the expression and transformation of rTregs and aTregs in 83 cases of recipients with normal status post-LT. The percentages of CD45RA, CD45RO, CD31 in CD4Tregs were detected by flow cytometry and the effective factors were analyzed. In LT recipients, the percentage of CD45ROTregs in CD4Tregs was higher than that of CD45RATregs. There was significant difference in the ratio of positive Foxp3 between CD45RATregs and CD45ROTregs. Percentage of CD45RATregs was higher in pediatric group than that in adult group, whereas percentage of CD45ROTregs was lower in the pediatric group. However, it was different only in CD45ROTregs in various survival periods post-LT. In conclusion, Tregs pool in human was heterogeneous post-LT and contained different subsets in phenotypes. Upon stimulation by donor graft, percentages of CD4Tregs and CD45ROTregs were increased post-LT and most of rTregs was transformed into aTregs in peripheral blood, and rTregs and aTregs were both related to recipients' ages.