Chemokines differently support migration of pbNK and dNK cells through progesterone-treated decidual ST cells. Highly purified pbNK cells or dNK cells from the same women in the first trimester of pregnancy were assayed for their ability to migrate through a monolayer of primary cultures of ST decidual cells grown in the presence of progesterone (100 nM) as above. All data are expressed as the mean plus SD of the percentage of migrated cells obtained from 3 independent experiments. *P < .05, as evaluated by comparing chemoattractant-induced migration versus control medium by Student t test.