IFN-early, not IFN-late, inhibits CD40L-triggered IL-12. (A) Affymetrix analysis shows relative expression of IL-12B subunit in iDCs, mDCs, and mDCs + CD40L. Untreated, black line. IFN-α/β–treated iDCs, gray line. (B) Supernatants from DCs matured alone (mDCs), in the presence of IFN-α/β (IFN-DC), or DCs exposed to IFN-α/β after maturation (mDC + IFN) were treated with CD40L as indicated for 2 hours. IL-12p70 was measure by ELISA and the average of triplicate wells are reported. P calculated by paired t test are shown.