Tolerogenic MDSCs incubated with VSSP are conditioned to cross-prime antigen-specific CD8
T cells. CD11b+Gr1+ cells isolated from EL4 and EG.7 TB mice, inoculated or not with VSSP, were treated in vitro with 10 μg/mL of both OVA and VSSP (A and C) or left untreated (A and B). To assess the capacity of these cells to accomplish a detectable cross-priming, antigen-specific CD8+ T cells were isolated from OTI transgenic mice and cocultured at 1:1 ratio with MDSCs for 96 h. BM-DCs previously incubated with OVA, OVA and VSSP or pulsed with SIINFEKL peptide were used as controls (D and E). Graphs show the percentage of CD69+ cells as a measure of the activation of antigen-specific CD8+ T cells. ANOVA and Tukey’s tests were used for statistical comparison of the groups’ mean. Two experiments with similar results were performed.