Exogenous IL-12 overcomes IFN-α/β inhibition of CD40-dependent cross-presentation. (A) The schematic illustrates that IFN-α/β treatment (red) of iDCs during antigen capture and maturation inhibits CD40-induced IL-12 production. Exogenous IL-12p70 was added to DC/T-cell cultures and the effect on cross-presentation was assessed by ELISPOT. (B) T-cell activation by DCs cross-presenting apoptotic cells (DC x/p AC), DCs cross-presenting apoptotic cells loaded with influenza antigen (DC x/p flu-AC), or DCs matured in the presence of IFN-α/β cross-presenting influenza antigen (IFN DC x/p flu-AC) was monitored by IFN-γ ELISPOT. In addition to CD40L alone (media), recombinant human IL-12 (rIL-12p70) was added to the DC/T-cell cultures. Data from 3 donors was normalized to the donor-specific maximal T-cell response and the percent maximal T-cell response in the presence or absence of IFN-α/β and IL-12p70 is shown.