Enhanced Suppression of CD_4~+CD_(25)~+ Regulatory T Cells by Pregnant Level of Estrogen in Vitro

Objective To investigate whether the pregnant-level estrogen induce the expansion of CD4+CD25+ regulatory T cells and its suppression activity in vitro.Methods ① CD4+CD25+regulatory T cells labelled with CFSE were stimulated with anti-CD3 and anti-CD28 mAbs or PBS in the presence and absence of pregnant level estrogen(E2)(experimental group,control group A and control group B),or no any stimulus instead of PBS(placebo group).②CFSE-labelled CD4+CD25+ naive T cells were cultured with CD4+CD25+ regulatory T cells,which were pretreated for 2 hours with estrogen or not,and stimulated with anti-CD3 and anti-CD28 mAbs or PBS(experimental group,control group A and control group B).As placebo group,CFSE-labelled CD4+CD25+ naive T cells were treated only with PBS.After 120 hours,the proliferation of labelled cells was detected by FACS and analyzed by Modfit LT soft.Results Stimulated by anti-CD3 and anti-CD28 mAbs in 120 h,the proliferation index(PI) of CD4+CD25+regulatory T cells in experimental group were significantly higher than that in two control groups and placebo group.The proliferation of CFSE-labelled CD4+CD25+ naive T cells mediated with anti-CD3 and anti-CD28 mAbs was inhibited by CD4+CD25+regulatory T cells.estrogen pretreated CD4+CD25+regulatory T cells could further enhance this effect.Conclusion It suggested that high level of estrogen in gestation can induce the expansion of CD4+CD25+ regulatory T cells and enhance its suppression,and may play a pivotal role in the maternal-feto tolerance.