Blocking OX40L partially reversed the PGE₂-induced enhanced capacity of MoDCs to stimulate memory T-cell proliferation. MoDCs were matured with sCD40L in the absence (□) or presence (■) of PGE₂, pulsed with tetanus toxoid (TT), and cocultured with autologous CFSE-labeled PBMCs for 6 (A,B) or 12 days (C,D). Graded concentrations of a goat anti–human OX40L-neutralizing antibody (■) or control goat IgG (●) were added to cocultures with PGE₂-matured MoDCs, and T-cell proliferation was analyzed by CFSE dilution of live (Sytox Blue negative) cells. Percentages of proliferating, CSFE^lowCD3⁺CD4⁺ (A,C) or CSFE^lowCD3⁺CD8⁺ (B,D) T cells are presented. Mean values and SEM of at least 4 independent experiments with different donors are shown. *P < .05; **P < .01; ***P < .001.