Progesterone Decreases in vitro Indoleamine 2, 3-dioxygenase Expression in Dendritic and CD4 Cells from Maternal-Fetal Interface of Rats.

Problem: Several mechanisms contribute to the tolerogenic state observed during pregnancy, such as the activity of the enzyme indoleamine 2, 3-dioxygenase (IDO). This initializes the catabolism of tryptophan, inducing T cells to apoptosis due to its deprivation and by the action of its catabolites in the placental microenvironment. Progesterone plays an important part on immunological tolerance mechanisms during pregnancy; however, there is no evidence it is related to IDO activity.