Functions of human decidual NK cells.

The main population of lymphocytes found in the human decidua during early pregnancy are NK-like cells with a distinctive phenotype, CD56bright CD16- CD3-. These cells are in close association with invading trophoblast that may be their in vivo target. We have examined three aspects of decidual NK function in vitro: cytotoxicity, proliferation, and cytokine production. The functional assays indicate uterine lymphocytes differ fundamentally from both PBL and even from classical circulating NK cells. Their role in the establishment of normal pregnancy remains unknown.