Promotion of Early Pregnancy Events in Mice and Humans by Uterine Natural Killer Cells

Abstract

Mammalian pregnancy is a unique immunologic situation in which the maternal immune system recognizes and accepts an antigenically disparate tissue, the conceptus. Currently, our understanding of human peri-implantation and early gestational events is largely based on animal studies, particularly mice. Although immune cells are present in the uterus before conception or blastocyst implantation, huge increases in immune cell numbers and the differentiation of specialized lymphocyte subsets are induced in species with hemochorial placentation during the process of decidualization.