Dendritic cells in Physiologic and pathologic human pregnancy

Dendritic cells (DCs) are a heterogeneous population of professional antigen-presenting cells that bridge the arms of innate and adaptive immunity. Endowed with the ability to either initiate adaptive immune responses or induce T cell tolerance, DCs are crucially involved in the maintenance of immune homeostasis during all phases of human pregnancy. At the site of implantation they collaborate with other innate immune cells to provide the proangiogenic and proinflammatory environment that is needed for decidual and trophoblast development. During pregnancy progression, DCs promote fetal tolerance for allowing the fetus to grow and develop in the uterus despite being recognized. At the end of pregnancy, DCs are likely to actively participate in labor.Although DCs in pregnant women have been characterized mainly at the maternal-decidual interface, changes occurring in DCs during pregnancy can be demonstrated in peripheral blood, as well. Evidences accumulated so far demonstrating profound changes occurring in circulating DCs during normal and pathologic human pregnancy will be illustrated and discussed highlighting their relevance to the comprehension of the role played by DCs in maternal immune adaptation to pregnancy and fetal health.