Figure 4: Effect of MDSCs on tumor-dLN T cell activation using anti-CD3/anti-CD28 antibodies. MACS-enriched intratumoral MDSCs were isolated from tumor-bearing mice at week 5 after tumor implantation and were cocultured with tumor-draining lymph node cells from DPX-vaccinated, non-vaccinated controls or LN cells from tumor-free naïve mice during anti-CD3/anti-CD28-mediated T cell activation. Left panel represents T cell activation in the absence of MDSCs and the right panel with MDSCs coculture. IFN-γ producing CD8 T cells were detected by intracellular staining as described in methods. Representative histograms are from 4 mice per group, from one of two experiments with similar results are shown.