Characterization of a lymphocyte subset displaying a unique regulatory activity in human decidua.

One of the most intriguing mechanisms of early pregnancy is the maternal immune tolerance toward her semi-allogeneic fetus, specifically in face of the accumulation of lymphocytes to high numbers at implantation sites. Here, we propose that a regulatory decidual lymphocyte (dL) population prevent the activation of reactive T cells and by that may maintain immune tolerance in the decidua. dLs were isolated from first trimester decidua and were then co-cultured with PBMC that were stimulated with anti-CD3 mAbs.