Hematopoietic cells are involved in SRA/CD204 deficiency-enhanced antitumor immunity after OVA-MPL vaccination. (A) Enhanced antitumor efficacy in immunized SRA^−/− mice. Age-matched WT and SRA^−/− C57BL/6 mice (n = 5) were immunized twice at a weekly interval with 50 μg of OVA protein mixed with 10 μg of MPL. One week after booster immunization, mice were challenged with 3 × 10⁵ B16-OVA tumor cells (*P < .001, SRA^−/− vs WT mice, ANOVA test). Experiments were performed twice, and a representative experiment is shown. (B) Hematopoietic cells required for the enhanced vaccine activities in SRA^−/− mice. Recipient SRA^−/− mice (n = 5) were whole body irradiated and received 10⁷ total BM cells from donor WT or SRA^−/− mice. Eight weeks later, recipient mice were immunized with OVA-MPL and challenged with 2 × 10⁵ B16-OVA cells (P < .001, SRA^−/− BM vs WT BM, ANOVA test). Results are representative of 2 separate experiments.