Contribution of Seminal Plasma to the Female Immune Regulation in Embryo Implantation

In reproduction, in which there is an exposure to paternal alloantigens at different stages, the female genital tract develops a tolerogenic response during implantation and pregnancy. We summarize data from the literature which support an important contribution of seminal plasma to the maternal immune tolerance to the conceptus and to the establishment of pregnancy. Seminal plasma has for long been considered as a medium for the survival and transport of sperm. However, other important roles related to early pregnancy in the female have been described. Immunoregulatory molecules present in seminal plasma, like prostaglandins and different cytokines, induce throught different mechanisms tolerance to paternal/trophoblast antigens and prepare the uterine endometrial tissues for embryo implantation. A switch from an early pro-inflammatory to an anti-inflammatory state is partly induced by seminal plasma molecules at implantation. In this review we focus on the importance of prostaglandins and TGF-β. This cytokine is one of the most important driver for the induction of T regulatory cells proliferation. It can be stated that the decrease in any of the immunomodulatory molecules from seminal plasma reduces the immunotolerance mechanisms during embryo implantation.