Immunologically Mediated Male and Female Reproductive Failure

Pregnancy poses a unique immune condition actively modulated to protect the mother against pathogens and prevent damage to the fetus, the result of a combination of signals and responses originating from the maternal immune system and the fetal-placental immune system. Seminal fluid components can perturb the female reproductive tract, both promoting the survival of spermatozoa and facilitating the implantation of embryos. The prevention of autoimmunity to sperm-associated antigens is dependent upon the presence of both an anatomical blood-testis barrier and tolerance mechanisms mediated by T regulatory (Treg) lymphocytes. Significant roles are played by the interactions of Treg cells, dendritic cells, uterine natural killer cells, and stromal cells of the decidua through the mediation of cytokines and chemokines in the regulation of trophectoderm outgrowth and early placental development. Impairment of these processes may have implications leading to clinical abnormalities of pregnancy.