Cross-presentation of TAA by splenic MDSCs is abrogated in VSSP-inoculated TB mice. (A-B) EL4 and EG.7 TB mice were injected with VSSP and cross-presentation of the OVA peptide SIINFEKL was detected by FACS on splenic CD11b+Gr1+ cells, two days after the last dose of the adjuvant. (A) Histograms show the staining with the mAb specific for H-2Kb-SIINFEKL peptide complexes on gated CD11b+Gr1+ cells for one representative mouse per group. (B) Mean ± SD of the percentages of MDSCs expressing OVA peptide bound to MHC I molecule (n = 9 to n = 15 individual mice per group belonging to three replicated experiments). (C) Mice with EG.7 tumors were vaccinated with OVA protein mixed with VSSP or polyI:C. Another group of TB mice was inoculated with VSSP and additionally received OVA/polyI:C vaccine. EL4 TB mice were included as negative controls. Cross-presentation of OVA antigen was analyzed as described above. These data are from two independent experiments. Statistical analyses were performed with ANOVA and Tukey’s tests.