Definitive class I human leukocyte antigen expression in gestational placentation: HLA-F, HLA-E, HLA-C, and HLA-G in extravillous trophoblast invasion on placentation, pregnancy, and parturition.

Expression of HLA-F and HLA-G on the cell surface of actively migrating EVT supports their specific role in early EVT invasion and interactions with uterine natural killer cells. HLA-C's limited expression to the proliferative EVT suggests a protective role in the earliest events of implantation but not in active EVT invasion. We also show for the first time that HLA-C may be involved in parturition.