The enhanced primary T-cell response induced by PGE₂-matured MoDCs can be inhibited by OX40L blockage. MoDCs were pulsed with KLH and matured with sCD40L in the absence (□) or presence of PGE₂ (■) for 48 hours. Freshly isolated autologous PBMCs were labeled with CFSE and cocultured with MoDCs at a PBMC/MoDC ratio of 10:1. Where indicated, 5 μg/mL of a neutralizing goat anti–human OX40L antibody or a control goat IgG was added. CD4⁺ (A,C) and CD8⁺ (B,D) T-cell proliferation on day 6 (A,B) or 12 (C,D) of the coculture was analyzed by flow cytometry by CFSE dilution of live (Sytox Blue negative) cells. Mean values and SEM of 7 (A,B) or 4 (C,D) independent experiments with different donors are shown. *P < .05; **P < .01.