[Immunology of pregnancy]

The fetus expresses paternally inherited gene products and tissue-specific differentiation antigens. Hence, it can be considered as a semi-allogeneic graft towards which the maternal immune response is characterized by tolerance instead of rejection. As such, the pregnancy represents a challenge to the laws of transplantation. For the immunologist, the question is not why some women miscarry, but rather, why most women do not miscarry? A bulwark of proscriptive or inhibitory influences must be built to ensure an absence of anti-fetal reactivity. The mechanisms underlying the induction of tolerance are poorly understood. Failure to obtain an adequate maternal immune response might be responsible for some forms of miscarriages, especially recurrent spontaneous abortions. Increased knowledge of those mechanisms could have implications in various fields, such as infertility, transplantation and oncology.