Type I IFN is required for efficient accumulation and activation of DCs in the dLN. B6, IFN-αβR^−/−, and IL-12–blocked mice were immunized in the footpad with 5 μg of OVA-TLR7a conjugate that had been labeled with the fluorescent dye, Alexa-Fluor 488. At the indicated time points after immunization, popliteal LNs draining the foot were harvested, minced, and digested with collagenase/DNase. The frequency of cells or the mean fluorescence intensity values shown were gated on (A) CD11c⁺ Alexa-Fluor 488⁺ cells, (B) CD11c⁺ cells, (C) or CD11c⁺ CD86⁺ cells. The data shown are representative of 2 independent experiments, 3 mice per group. Statistical analyses (*) were performed as described in “Statistical analyses.” The summary of P values, as indicated by (*), denote statistical significance of differences between the means of the WT or IL-12–blocked mouse and the means of IFN-αβR^−/− mouse.