Human decidual tissue appears to play an important role not only in nurturing the implanted embryos, but also in preventing its rejection by the maternal immune system. Insight into the maternal immunologic modulations during implantation is our main research interests. Our previous studies have shown that most lymphocytes in deciduae are natural killer cells. However, their phenotype is CD16-CD56+CD3-, which is different from that of peripheral natural killer cells. More importantly their cytotoxic activity is decreased and they can’t attack the cytotrophoblasts. All of these contributes to no rejection developing at the fetomaternal interface and are related to success of pregnancy.

In 1994, a new cytokine IL-15 was first discovered, which could act on the IL-15 and IL-2 receptors to stimulate the activation and propagation of the lymphocytes. Let us want to study the critical role of IL-15 in the endometrial lymphocytes. In this study, we try to analyze the distribution of IL-15 and its receptor in deciduae. We will clarify whether the IL-15 receptor exists on the decidual natural killer cells and it is regulated by sexual hormones or not and whether their cytotoxic activity will change after IL-15 action. Furthermore, we will demonstrated whether the IL-15 receptor exists on the embryo cells and IL-15 might improve the quality of the embryo. We also design a co-culture system of the embryo and autologous endometrial cells to improve the success rate of in vitro fertilization.