Do decidual NK cells remember pregnancy? A possible explanation for preeclampsia risk in primiparity and primipaternity

Abstract

Natural killer (NK) cells, lymphocytes of the innate immune system, are able to kill tumor and infected cells. Recent studies suggest that NK cells possess some features of adaptive immunity including a certain type of immune cell memory, termed trained immunity. During human pregnancy NK cells constitute the most abundant lymphocyte population found at the maternal fetal interface, the decidua. These NK cells (termed dNK) possess unique phenotypic and functional properties and are considered regulators of remodeling of the maternal fetal interface. We propose that dNK cells “remember” pregnancy. Thus dNK from parous and nulliparous women may differ. First pregnancy and pregnancy with a new father are known risk factors for the development of preeclampsia. We suggest that trained memory of dNK may be the missing link in the immune basis of the risk of preeclampsia in primiparity. This mechanism may be involved in several disorders of pregnancy with placental origins especially preeclampsia.