Peripheral blood dendritic cells in human healthy and pathological pregnancy

Pregnancy provides a major challenge to the maternal immune system, which must tolerate fetal alloantigens encoded by paternal genes for allowing the fetus to grow and develop in the uterus despite being recognized. Dendritic cells (DCs) are widely distributed potent antigen-presenting cells that bridge the arms of innate and adaptive immunity. They can either promote or prevent immune activation, thus playing a central role in the control of immune tolerance. DCs in pregnant women have been characterized mainly at the maternal-decidual interface, where their state of activation has emerged as one of the key players influencing the feto-maternal immunological equilibrium. Growing evidences indicate that during pregnancy also DCs circulating in the peripheral blood, which is the most accessible source of DCs, undergo changes that may be relevant to the adaptation of maternal immune responses needed to allow fetal growth. Moreover, alterations of circulating DCs that may likely reflect alterations occurring in the decidua have also been described in pathological pregnancies, such as in pregnancies complicated by intrauterine growth restriction or pre-eclampsia