Figure 5. DCs drive bulk production of type I IFN triggered by anti–mDEC-pdA:dT.

(a) B6 (wild type (WT)) or DEC knockout (KO) mice were lethally irradiated and injected with bone marrow cells from DEC KO mice (KO → B6) or B6 mice (B6 → KO), respectively. Chimeras and WT or DEC KO control mice were inoculated with 10 µg of Alexa 647–labeled anti–mDEC-pdA:dT. Spleens were harvested, and mAb uptake was evaluated by FACS in CD8α⁺ DCs (left). Bar graph (right) shows serum IFN-α as the mean ± s.d. of four mice in two experiments. (b) CD11c-DTR mice were inoculated with diphtheria toxin (+ DT) or PBS (− DT) 24 h before the inoculation of 10 µg of anti–mDEC-pdA:dT. ELISA was performed to determine serum IFN-α 6 h later. Shown is the mean ± s.d. of three animals per group. (c) B6 or DEC KO mice were inoculated intraperitoneally with 10 µg Alexa 647–labeled anti–mDEC-pdA:dT. Uptake of labeled mAbs by splenic DC subsets was evaluated by FACS. Results from one experiment of two is shown. (d) Spleens of mice inoculated with 10 µg of mAb–pdA:dT were harvested, and DC populations were FACS-sorted and cultured. IFN-α production was assessed by ELISA in the culture supernatant. Mean ± s.d. of two experiments is shown. (e) Surface costimulatory markers (CD86, MHCII and CD40) were evaluated 12 h after inoculation of 10 µg of anti–mDEC-pdA:dT or of PBS by FACS gating on the indicated DC populations. Fluorochrome-labeled isotype controls are shown in gray.