Antigen-specific T-cell responses after DC transfer. CD27^−/− recipients received WT or CD27^−/− OT-I T cells, and 1 day later they were injected intravenously with Flt3L-induced, OVA_257-264 peptide-loaded or unloaded total DCs (A,B) or flow cytometrically sorted DC subsets (C) derived from CD27^−/− (control) or CD70tg;CD27^−/− (CD70tg) donor mice. (A) Percentages of H-2K^b/OVA_257-264 tetramer-positive cells among CD8⁺ T cells in blood of recipients at the indicated days after DC transfer. (B) Representative flow cytometric data of the same experiment as in panel A depicting tetramer⁺ CD8⁺ T cells in blood of DC recipients at day 6 (peak of the response in CD70tg recipients) and day 10 (contraction phase). Numbers indicate percentages of H-2K^b/OVA_257-264 tetramer-positive cells within the CD8⁺ T-cell population. (C) Expansion of WT OT-I T cells in response to OVA_257-264 peptide-loaded CD8⁺ or CD8⁻ cDC subsets derived from control or CD70tg donor mice. Data in panels A and C represent mean values (+ SEM) for 4 to 5 mice per group and are representative of 2 or more independent experiments. Asterisks indicate statistical significance between the groups that received control or CD70tg peptide-loaded DCs and WT T cells according to Student t test for *P < .05, **P < .01, and ***P < .001.