Combined Th1-cell and anti–IFN-γ treatment leads to further reduction of tumor growth. (A) On day 3 after injection of CT26-EpCAM tumor cells, mice were irradiated, treated with 500 μg anti–IFN-γ antibody, and on day 4 EpCAM-reactive Th1 cells were injected. Tumor weight of PBS-treated (n = 18), Th1 cell–treated (n = 10), and combined-treated (n = 8) mice was analyzed on day 17. Δ, reduction of tumor weight of Th1 cell–treated mice compared with PBS controls (*P < .05). (B) Real-time PCR data of tumors. Multiplex reactions were run in triplicates, and samples were normalized to the housekeeping gene HPRT. Relative expression of genes of interest is represented as fold differences of the mean of Th1 cell-treated mice (n = 7) or combined-treated mice (Th1 cells and anti–IFN-γ, n = 6) over PBS controls (n = 14) on day 17 after tumor cell injection. A strong up-regulation of IFN-γ was found in tumors treated with both Th1 cells and anti–IFN-γ mAb (*P < .05). Experiments were performed as described in “Methods.”