Evaluation of the effects of NK- and NKT-cell ligands on T-cell priming to NIH3T3 cells transfected with OVA antigen mRNA. (A) C57BL/6 mice were immunized with NIH3T3-ova, CD1d^hi-NIH3T3-ova, NIH3T3/Gal-ova, or CD1d^hi-NIH3T3/Gal-ova. Spleen cells were collected one week later to test for the development of OVA-specific T-cell immunity using K^b/OVA_257-264 tetramer-PE and CD8-FITC. The number shown indicates the percentage of K^b/OVA_257-264 tetramer–positive cells of the total CD8⁺ T cells. (B) C57BL/6 mice and Jα18^−/− mice were immunized with CD1d^hi-NIH3T3/Gal-ova. Spleen cells were analyzed as shown in panel A. The number shown indicates the percentage of K^b/OVA_257-264 tetramer–positive cells of the total CD8⁺ T cells. (C) Mice were immunized with Rae-1ϵ-NIH3T3-ova, Rae-1γ-NIH3T3-ova, Mult1-NIH3T3-ova, or CD70-NIH3T3-ova. Spleen cells were analyzed as shown in panel A. (D) Spleen cells from different groups of immunized mice were collected one week after immunization. CD8⁺ T cells were positively selected from the spleens of naive or immunized mice and cocultured with OVA_257-264 peptide-pulsed CD11c⁺ cells for 36 hours. IFN-γ secretion from CD8⁺ T cells in response to OVA_257-264 peptide was evaluated by ELISPOT (Document S1). All data are means plus or minus SEM from 3 independent experiments with 2 mice per group. **P < .001 (indicated in panels: Rae-1ϵ-NIH3T3-ova and CD70-NIH3T3-ova vs CD1d^hi-NIH3T3/Gal-ova).