EP1 and EP3 receptors regulate Flt3L-mediated DC development. (A) Lin^neg BM cells cultured for 9 days in Flt3L-supplemented media with indomethacin alone or with indomethacin plus selective EP receptor agonists, and DC generation was measured by flow cytometry (mean ± SEM; n = 6 mice assayed individually; from 2 experiments). (B left) In vitro, Flt3L-dependent DC generation from Lin^neg BM cells in the presence of EP1 and EP3 receptor antagonist (mean ± SEM; n = 8 mice assayed individually; from 3 experiments). (Right) Total DC number per femur in mice treated with indomethacin or EP1 or EP3 antagonists in vivo (mean ± SEM; n = 4 mice assayed individually). (C) Lin^neg BM cells cultured for 5 days in Flt3L-supplemented media with indomethacin alone or with selective EP receptor agonists. Surviving expression in pre-cDC gated cells was determined by flow cytometry (mean ± SEM; n = 3 mice assayed individually). *P < .05 compared with vehicle; †P < .05 compared with indomethacin. (D) Total CD11c⁺ MHCll⁺ DCs in the BM and spleen of EP1 and EP3 knockout mice and EP1/EP3 double knockout mice (mean ± SEM; n = 3 mice assayed individually). *P < .05 compared with wild-type control. V indicates vehicle; and Indo, indomethacin.