Immune tolerance at the maternal‐placental interface in healthy pregnancy and pre‐eclampsia

Abstract Aim The objective of this review is to describe the immunological mechanisms which facilitate maternal tolerance at the maternal‐placental interface, and to discuss how these mechanisms are disrupted in pre‐eclampsia. Methods A literature review was performed based on the analysis of papers available on PubMed. The most important and relevant studies regarding the immunological mechanisms which facilitate maternal tolerance in healthy pregnancy and pre‐eclampsia are presented in this article. Results The maternal‐placental interface is the site where the immune tolerance begins and develops. Within the innate immunity, natural killer cells, macrophages and dendritic cells play a pivotal role in tolerance through regulation of inflammation. On the other hand, within the adaptive immunity, the correct increase of regulatory T cells is crucial for ensuring immune tolerance toward placental cells. Disturbances in maternal tolerance can lead to the appearance of pregnancy complications such as pre‐eclampsia, which has a considerable impact on perinatal morbidity and mortality. Conclusion Our partial knowledge of immunological mechanisms involved in tolerance at the maternal‐placental interface indicates that pre‐eclampsia is characterized by alterations of this maternal immune tolerance, which could represent the origin of the disease.