OVA captured in vivo is cross-presented by pDCs after in vitro stimulation. Mice were injected intravenously with OVA (9 mg). Two hours later, pDCs and cDCs were purified and various concentrations of both DC subsets were cocultured with either culture medium alone (CM), R848 (1 μg/mL), or CpG (10 μg/mL) and 2.5 × 104 CFSE-labeled OT-I T cells. CFSE profiles of OT-I T cells were analyzed by flow cytometry 72 hours later. (A) CFSE profiles obtained with 2 × 105 DCs are shown for both DC subsets and for each conditions as indicated. Proliferating OT-I T cells are gated in M1. (B) Percentages of gated proliferating T cells are plotted according to the number of pDCs (top panel) or cDCs (bottom panel) per well in culture medium (○, CM), or in the presence of R848 (●) or CpG (■). One representative experiment of 3 is depicted.
