Using ex vivo-activated OVA-specific OT-1 CD8 T cells in OVA- or OVA-peptide-expressing syngeneic mouse tumor models, we demonstrated that IFN-γ produced by a limited number of transferred CD8 T cells targeted tumor vascular endothelial cells early after ACT (Day 1.5), thus triggering profound antitumor effects. The gene discussed is CD8A; the disease is neoplasm.