αDEC-205 antibodies target OVA to MHC class 2⁺ cells and induce T-cell proliferation. (A-B) αDEC-OVA conjugates were injected into the footpads of mice. Twenty-four hours later tissue sections from LNs were stained with PE-labeled goat anti-rat antibodies (to detect injected αDEC-OVA [red]). Specimens were further double labeled with FITC-αMHC class 2 antibodies (A) or FITC–SER-4 antibodies (B), respectively (green). Colabeling is indicated by yellow. Original magnification, ×200. (C) Twenty-four hours after the injection of 10 μg antibody-OVA conjugates, CD11c⁺ and CD11c^– cells were prepared and cocultured with OVA-specific DO11.10 T cells. T-cell proliferation was assayed by ³H-thymidine incorporation. (D) A mixture of αDEC and OVA and of αDEC or OVA alone was injected, and CD11c⁺ cells were tested for antigen presentation as in panel C. (E) Mice were reconstituted with CFSE-labeled, OVA-specific DO11.10 T cells and injected with different antibody-OVA conjugates as indicated. Forty-eight hours later, LN cells were prepared and stained with PE-labeled αCD4 antibody. CFSE labeling was assayed by FACS after gating on CD4⁺ cells, and T-cell division is indicated by dilution of the dye (ie, decrease of fluorescence).