Fig. 6.

Analyses of NXS2 tumor-reactive CD8⁺ T cells in vivo. a Tumor-specific immune memory protecting mice from NXS2 re-challenge. A/J mice (n = 8), which were immunized with the 47-LDA vaccine in the presence of IL-15 and IL-21 genes and remained tumor-free for at least a 3 month period after s.c. NXS2 challenge (filled square), were re-challenged with 10⁶ NXS2 cells. Control mice were challenged with NXS2 cells only (open square). b CD8⁺ T cells from A/J mice (n = 8), which had been immunized with the 47-LDA vaccine in combination with IL-15 and IL-21 genes and rejected s.c. NXS2 tumor challenge, were used for adoptive transfer (filled square). For the adoptive cell transfer, mice that were challenged s.c. with 10⁶ NXS2 cells were sublethally irradiated (500 rad) and treated by i.v. injection with freshly isolated CD8⁺ T cells from the cured mice (2 × 10⁷ cells). All recipient mice were vaccinated every 2 weeks by i.v. injection of 47-LDA-transfected DCs (2 × 10⁶ cells) and i.m. injection of IL-15 and IL-21 genes delivered at the time of immunization and 5 days later, respectively. NXS2-challenged mice that received CD8⁺ T cells from untreated animals served as controls (open square). Survival was defined as the point at which mice were sacrificed due to extensive tumor growth. Kaplan–Meier survival plots were prepared, and significance was determined using logrank Mantel–Cox method