Figure 3. Histological evidence for tumor cell elimination after application of anti-PD-L1 antibodies.

NP8 tumor mice were treated as in described in Figure 2. Histologic examination of tumors of treated mice revealed massive reductions of T-Ag as well as of PD-L1 positive cells in comparison to that of untreated NP8 tumor mice, whereas at the same time the fraction of dying cells increased, as confirmed by the strongly enhanced presence of caspase-3 positive cells (magnifications are the same in all pictures; bar: 100μm).