Human Placental Cytotrophoblasts Attract Monocytes and Cd56bright Natural Killer Cells via the Actions of Monocyte Inflammatory Protein 1α

During human pregnancy, the specialized epithelial cells of the placenta (cytotrophoblasts) come into direct contact with immune cells in several locations. In the fetal compartment of the placenta, cytotrophoblast stem cells lie adjacent to macrophages (Hofbauer cells) that reside within the chorionic villus stroma. At sites of placental attachment to the mother, invasive cytotrophoblasts encounter specialized maternal natural killer (NK) cells (CD56bright), macrophages, and T cells that accumulate within the uterine wall during pregnancy. Here we tested the hypothesis that fetal cytotrophoblasts can direct the migration of these maternal immune cells. First, we assayed the chemotactic activity of cytotrophoblast conditioned medium samples, using human peripheral blood mononuclear cells as targets. The placental samples preferentially attracted NK cells (both CD56dim and CD56bright), monocytes, and T cells, suggesting that our hypothesis was correct. A screen to identify chemokine activity through the induction of a Ca2+ flux in cells transfected with individual chemokine receptors suggested that cytotrophoblasts secreted monocyte inflammatory protein (MIP)-1α. This was confirmed