Different phenotypes of CD4+CD25+Foxp3+ 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 CD45RA+Tregs (resting Tregs, rTregs) and CD45RO+Tregs (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 CD4+Tregs were detected by flow cytometry and the effective factors were analyzed. In LT recipients, the percentage of CD45RO+Tregs in CD4+Tregs was higher than that of CD45RA+Tregs. There was significant difference in the ratio of positive Foxp3 between CD45RA+Tregs and CD45RO+Tregs. Percentage of CD45RA+Tregs was higher in pediatric group than that in adult group, whereas percentage of CD45RO+Tregs was lower in the pediatric group. However, it was different only in CD45RO+Tregs 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 CD4+Tregs and CD45RO+Tregs 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.