Figure 4.

Prior immunization leads to increased levels of T-cell infiltration into the tumor. (a) Mice treated as in (Figure 3) were sacrificed 72-hours after treatment and tumors either frozen and sectioned for staining with anti-CD3 antibody (red) and viral GFP expression (green) (top) or (b) tumors were dissociated and cells stained with fluorophore labeled antibodies to CD3 and CD4 or CD8 and percentage positively stained cells determined by flow cytometry (bottom) (n = 4/group) (*P < 0.05). GFP, green fluorescent protein; vvDD, vaccinia virus.