Figure 3.

Intratumoral injection of DTA-1 Ab more effectively activated tumor-specific immunity. (a) IFN-γ ELISpot assay in response to stimulation of CT26 tumor cells. DTA-1 Ab was injected into the CT26 subcutaneous tumor (IT) or into the peritoneal cavity (IP). Seven days later splenocytes were co-cultured with CT26 tumor cells, and stained with biotinylated anti-mouse IFN-γ antibody to detect captured IFN-γ (n = 3). P value for DTA-1 IP vs IT, as analysed by t-test. (b) The increase of tumor-specific CD8⁺ T cells in DTA-1 Ab IT-treated mice. The splenocytes were isolated seven days after DTA-1 Ab administration, and CT26-specific AH-1-tetramer-positive cells were analyzed by flow cytometry (upper panel). The ratio of AH-1 tetramer⁺ cells among CD8⁺ cells (n = 4) (lower left panel). Total cell number of AH-1 tetramer⁺ CD8⁺ cells in 1 × 10⁴ events (n = 4) (lower middle panel). The ratio of p815 tetramer⁺ cells among CD8⁺ cells (n = 4) (lower right panel). P values for PBS vs DTA-1 IP and DTA-1 IP vs IT, as analysed by t-test. (c) Re-challenge of CT26 tumor cells into the mice cured by the DTA-1 Ab treatment. CT26 cells were re-challenged at a few days after tumor rejection (n = 9).