CD8α⁺ and CD8α^– DCs from ICSBP^–/– mice exhibit defective ability to capture Ags. Splenic CD11c⁺ DCs were purified from ICSBP^–/– and WT mice by magnetic cell sorting. DCs were incubated for 40 minutes either with 1 mg/mL DX-FITC (A,C-D) or with 0.2 mg/mL OVA-FITC (B-D), washed in cold PBS, and then stained with PE-labeled anti-CD8α mAb. (A-B) Density plots represent the uptake of FITC-conjugated OVA (A) or DX (B) and the expression of CD8α in CD11c⁺ s-DCs incubated with the Ag at 37°C or, as a control, at 4°C. (C-D) Histograms represent the uptake of Ag in CD8α⁺-gated (C) and CD8α^–-gated (D) s-DCs populations. Data are expressed as the mean percentage of FITC⁺ cells ± SD of 3 separate experiments. *P < .01; **P < .05, ICSBP^–/– versus WT. (E) CD11c⁺ s-DCs were incubated for various times with DX-FITC or OVA-FITC and then labeled with anti-CD8α mAb. Each dot represents the amount of FITC-conjugated Ag internalized by WT (○) and ICSBP^–/– (▴) in CD8α⁺-gated (left panels) and CD8α^–-gated (right panels) s-DCs. Zero time represents the background fluorescence of cells incubated with the Ag at 4°C. Data are representative of 2 separate experiments.