The decidual gamma-delta T cells up-regulate the biological functions of trophoblasts via IL-10 secretion in early human pregnancy

The functions of decidual γδT cells in early human pregnancy are not fully understood. The present study was undertaken to characterize the action of decidual γδT cells, and analyze their regulatory roles in proliferation and invasion of trophoblasts in early human pregnancy. It was revealed that decidual γδT cells were a CD4− and CD8− subset whose numbers increased significantly in either the decidua or peripheral blood. The main cytokines synthesized in decidual γδT cells in decreasing concentration were; IL-10 > TGF-β > TNF-α ≥ IFN-γ, with little IL-2 or IL-4 being produced. Decidual γδT cells promoted trophoblast proliferation and invasion, and suppressed trophoblast apoptosis through IL-10 secretion in co-culture. These results suggest that γδT cells in human decidua might play an important role in the Th2 bias at maternal–fetal interface and in the development and progression of the placenta, which is beneficial to maternal immunotolerance toward the fetus in early human pregnancy.