Immunological Response during Pregnancy in Humans and Mares

The immunology of pregnancy deals with the immune responses of a mother and her fetus to each other. More knowledge has been acquired over the last decade to give insight into the complicated immunological processes that help the developing fetus to survive in most circumstances. During this unusual state, the mother’s immune system must remain tolerant to paternal major histocompatibility complex (MHC) antigens while retaining normal immunological competence for pathogen defense, which is a difficult act. In the last decade, numerous processes have been revealed that may explain why the mother does not reject the foreign fetus. To understand how these processes work, the need to look at both fetal and maternal aspects, including trophoblast cell characteristics, local maternal factors, and changed MHC class I expression, is required. Horses, because of their unique anatomy and physiology, are a very useful animal model in pregnancy immunology research. In pregnant mares, chorionic girdle cells generate cytotoxic antibodies to paternal MHC class I antigens, enabling a more in-depth study of these invasive trophoblasts and their effect on the mother’s immune system. Therefore, this review will concentrate on the immune response during pregnancy in both humans and horses.