Migration of pbNK cells from pregnant and nonpregnant women or male donors through decidual ST cells: effect of progesterone. Highly purified pbNK cells isolated either from first-trimester pregnant women (A) or male donors (B) or nonpregnant women (C) were assayed for their ability to migrate through a monolayer of primary cultures of ST cells grown with or without progesterone (100 nM) using different concentrations of CXCL12/SDF-1, CX3CL1/fractalkine, or CXCL10/IP-10 as chemoattractants. All data are expressed as the mean plus SD of the percentage of migrated cells obtained from 4 independent experiments. * and **, P < .05, as evaluated by comparing chemoattractant- versus control medium (C)–induced migration or between migration through progesterone versus nonprogesterone-grown cells using Student t test, respectively.