Fig. 1

pMSC effect on NK cell proliferation. a Proliferation of resting unactivated cells (NK cells were induced to proliferate by 100 U/mL IL-2) was significantly decreased in the presence of pMSCs as compared to untreated resting unactivated NK cells, *P < 0.05. b IL-2-activated NK cell (NK cells were initially activated by 100 U/mL IL-2 for 72 h) proliferation decreased, but not statistically significant, in the presence of pMSCs as compared to untreated IL-2-activated NK cells, P > 0.05. Results of ten representative experiments in which the proliferation of resting unactivated or IL-2-activated NK cells cultured for 72 h with or without Mitomycin C-treated pMSCs at different ratios of NK to pMSC ranging from 1:1, 5:1, 25:1, 50:1, and 100:1 was measured using the MTS proliferation method. Experiments were conducted in triplicate using NK cells and pMSCs prepared from the peripheral blood of ten different healthy subjects and ten different normal human term placentae, respectively. Bars represent standard errors