Immunological microenvironment at the maternal-fetal interface.

The immune cells, especially innate immune cells (Natural Killer cells and Macrophages) residing at the maternal-fetal interface are playing critical roles during pregnancy. Here we discuss the immunological characteristic at the maternal-fetal interface during normal pregnancy. These key decidual immune cells are reshaped of their uterus-specific homeostatic functions within this uterus microenvironment. Through emphasizing the similarities and differences between decidua immune microenvironments with tumor or transplantation immune microenvironments, distinctive immune cell niche with activated, tolerant, proangiogenic and nurturing characteristic at the maternal interface is exhibited. Deeper understanding of the immunological microenvironment during pregnancy yield important insight not only into the pathogenesis of various human pregnancy complications, but also suggest ways to better manipulate these immune cells in cancer and transplant organs.