Figure 6: Frequency of intratumoral CD8 T and Treg cells in tumor-challenged mice at week five after challenge. Six days after implantation groups of mice were injected with either PBS alone or vaccinated using DPX-E7 or CE vaccine. Matched volume of tumor tissues was used to prepare single cell suspensions for cytospin slides. In (a), slides were stained with FITC conjugated anti-CD8β (upper panel) or anti-CD25 antibodies (lower panel; magnification). In (b), cytospin smears were double stained with anti-GARP-PE and anti-CD25-FITC antibodies and were analyzed using confocal microscopy to identify double-positive, activated Treg cells ( magnification). Smears shown are representative of 5-6 tumors processed in each group and subjected to blinded analysis.