Immune tolerance in pregnancy

This tolerance counters the immune response that would normally result in the rejection of something foreign in the body, as can happen in cases of spontaneous abortion.

One model for the induction of tolerance during the very early stages of pregnancy is the eutherian fetoembryonic defense system (eu-FEDS) hypothesis.

[10] The basic premise of the eu-FEDS hypothesis is that both soluble and cell surface associated glycoproteins, present in the reproductive system and expressed on gametes, suppress any potential immune responses, and inhibit rejection of the fetus.

[10] The eu-FEDS model further suggests that specific carbohydrate sequences (oligosaccharides) are covalently linked to these immunosuppressive glycoproteins and act as “functional groups” that suppress the immune response.

The major uterine and fetal glycoproteins that are associated with the eu-FEDS model in the human include alpha-fetoprotein, CA125, and glycodelin-A (also known as placental protein 14).

[15] The local and systemic immunologic changes are also more pronounced than in normal pregnancies, so it has been suggested that the higher frequency of some conditions in egg donation may be caused by reduced immune tolerance from the mother.

If a female has antibodies against these phospholipids, they will be destroyed through the immune response and ultimately the fetus will not be able to remain bound to the uterus.

An individual that presents with reproductive autoimmune failure syndrome has unexplained infertility, endometriosis, and repetitive miscarriages due to elevated levels of antinuclear antibodies circulating.