Conversion of CD4~+CD25~-naive T cells to CD4~+CD25~+ regulator T cells by pregnant level estrogen

Objective To investigate whether pregnant level estrogen can induce CD4+CD25-naive T cells to convert into CD4+CD25+ regulator T cells in vitro.Methods CD4+CD25-naive T cells were stimulated with anti-CD3 mAb and anti-CD28 mAb in the presence or absence of pregnant level estrogen(E2)(experimental group and control group),while CD4+CD25-naive T cell co-cultured with PBS was taken as placebo group.72 hours after stimulation,the changes of CD4+CD25+ T cells and CD4+Foxp3+ T cells were detected and the expression of Foxp3 mRNA were observed in three groups,respectively.Results The percentage of CD4+CD25+ T cells in control group was significantly higher than that in placebo group(P0.001).In comparison,the percentage of CD4+CD25+ T cells in the experimental group was markedly exceeded that in control group(P0.001).The percentage of CD4+Foxp3+ T cells in placebo group and control group showed no significant difference placebo group(P0.05).In experimental group,the percentage of CD4+Foxp3+ T cells was increased notably(P0.001).Higher expression of Foxp3 mRNA was found in experimental group compared to placebo group and control group(P0.001).But there was no difference of Foxp3 mRNA expression between placebo group and control group(P0.05).Conclusion High level of E2 in gestation may be a signal that lead to the expansion of peripheral CD4+CD25+Foxp3+ T cells in vitro.