(A) Cytotoxic action of CD8 T and NK cells infiltrating LL/2-luc or MC38-luc tumors was examined by flow cytometry with or without local CD25-targeted NIR-PIT. CD8 T and NK cells collected 1.5 hours after PIT were producing IFN-γ and IL-2 and had CD107a exposed on the cell surface, whereas the cells from nontreated tumors did not (n = 5; *P < 0.008, Mann-Whitney test). (B) One day after local CD25-targeted NIR-PIT, up-regulation of activation markers, CD69 and CD25, and continued production of IL-2 in both CD8 T and NK cells were observed (n = 5; *P < 0.008, Mann-Whitney test).