What can a pregnant horse’s immune responses tell us about organ transplants?



When a mammal becomes pregnant, the mother’s immune system is prevented from attacking the fetus as if it were an unfamiliar infection, but the mechanisms for this state of tolerance are not well understood. The Equine Genetics Center at the Baker Institute has pioneered methods to study the horse placenta and to determine the role of the placenta in protecting the fetus from immune destruction by the mother. The group has developed a novel experimental system of trophoblast transplantation that has demonstrated that the placenta acts to affect its own survival independently of the hormonal state of pregnancy and, most recently, that it can survive not only primary immune responses, but also the stronger secondary responses of the type that occur after vaccinations.

The Antczak lab’s work on the equine placenta contributes to knowledge of reproduction and pregnancy loss in horses, and in humans, too. It also has relevance to the important question of why the immune system can tolerate the unfamiliar tissues of the fetus, but not a foreign organ transplant. Without this type of new information, we are unlikely to ever be able to replace the immunosuppressive treatment of transplant patients with other approaches that do not increase their vulnerability to infectious diseases.