Changes in the Subpopulation of CD25+ CD4+ and FOXP3+ Regulatory T Cells in Decidua with Respect to the Progression of Labor at Term and the Lack of Analogical Changes in the Subpopulation of Suppressive B7-H4+ Macrophages - A Preliminary Report

The initiation of labor is accompanied by alterations in the level of maternal immune tolerance toward fetal antigens. It is a complex molecular response leading to a brief activation of the maternal immune system with an accompanying capacity to restrict this same activation. The aim of our study was to evaluate the subpopulation of regulatory T cells (Tregs) and B7-H4 macrophages in the decidua basalis during cesarean sections performed on patients in various stages of labor. The decidual tissue samples evaluated in our study were obtained from 23 pregnant women who underwent cesarean sections at term. Moreover, the patients were divided into three subgroups according to the progression of labor at the time of the cesarean. The presence of Treg cells and B7-H4 positive macrophages were analysed by fluorescence-activated cell sorter. The percentages of FOXP3(+) cells in the subpopulation of CD25(+) CD4(+) T lymphocytes found in the deciduas of patients decreased with the successive stages of labor, while the percentages of B7-H4 positive cells in the macrophage subpopulation remained almost constant. These changes in the Treg cell subpopulation in the decidua would seem to be related to a brief activation of the maternal immune system as labor begins and lack of analogical changes in the subpopulation of decidual suppressive B7-H4(+) macrophages that enable the restriction of this same activation as labor progresses.