Innate Lymphoid Cells in Normal Pregnancy and Pregnancy-Related Diseases

Innate lymphoid cells (ILCs) are a group of lymphocytes without diversified antigen receptors encoded by gene rearrangement on T and B cells. ILCs, which are tissue-resident innate immune cells, expressed particularly in the mucosa or the barrier surface, contribute to the formation of lymphoid organs, the maintenance of tissue homeostasis, and the regulation of antimicrobial defenses. It has been recently reported that ILCs were enriched at the maternal-fetal interface. During a successful pregnancy, the maternal immune system must tolerate a fetus as an allograft. With the new defined of ILCs, a number of studies have shown that three types of ILCs are involved in embryonic development and pregnancy maintenance as well as the occurrence and development of pregnancy-related complications. This article reviews the types and roles of ILCs in normal pregnancy and pregnancy-related diseases.