PGE2 inhibits DC-derived NK-cell activation. Monocyte-derived DCs were matured with IFN-γ/FMKp in the presence of different concentrations of PGE2. After 6-hour maturation, DCs were washed to remove the stimulation medium and matured for an additional 18 hours in AIM V medium only. (A) Quantitative comparison of IL-12 and IL-18 production as measured by ELISA. Results shown are the mean of combined data of at least 4 different donors + SEM (IL-12, n = 16; IL-18, n = 4). (B) Quantitative comparison of IL-12 and IL-18 production after stimulation with PGE2 either during or after 6-hour DC maturation as measured by ELISA. Results shown are the mean of combined data of at least 3 different donors + SEM (C) NK-cell IFN-γ production, as measured by ELISA, after incubation for 16 hours with DC supernatant. Results presented are the mean + SEM of combined data of 11 different donors. (D) NK-cell IFN-γ production, as measured by ELISA, after incubation for 16 hours with DC supernatant, or DC supernatant supplemented with 2 ng/mL IL-12, 100 pg/mL IL-18, or both. Results presented are the mean + SEM of combined data of 6 different donors. (E) Quantitative comparison of IL-23 production as measured by ELISA. Results shown are the mean + SEM of combined data of 4 different donors. *P < .05; **P < .01; ***P < .001.