Expression of OX40L and CD70 on ex vivo PBDCs and MoDCs strictly depends on PGE₂ stimulation. (A) Myeloid DCs were isolated from peripheral blood of healthy donors, and cell-surface expression of OX40L and CD70 (black bold lines) was measured by flow cytometry on ex vivo DCs, or PBDCs cultured for 48 hours in medium alone (no stimulus), or matured with sCD40L in presence or absence of PGE₂. (B,C) MoDCs were matured for 48 hours with sCD40L, LPS, poly I:C, or a cytokine cocktail consisting of TNF-α, IL-1β, and IL-6, in the absence or presence of PGE₂ and analyzed for surface expression of OX40L (B, black bold lines) and CD70 (C, black bold lines) by flow cytometry. (D) MoDCs were matured with sCD40L, whereas PGE₂ was present for the first 3 hours or 15 hours, or for the full period of maturation. Cell-surface expression of OX40L and CD70 (black bold lines) was assessed by flow cytometry after 48 hours of maturation. Isotype control stainings are presented as gray thin lines. A representative of 4 independent experiments with different donors is shown.