Figure 6.

The combination therapy enhanced specific antitumor immune responses

(A−C) An IFN-γ ELISpot assay of splenocytes from each treatment group. (A) The number of IFN-γ spots that responded to AKR cells was significantly higher in the combination group than in the other groups (p < 0.001). (B) A representative well from each group. (C) The number of IFN-γ-secreting spots stimulated by AKR cells, but not by Hepa1-6 cells, was significantly increased in the combination therapy group. The results are presented as the mean ± SEM (n = 7). (D and E) Rechallenge study. Mice (n = 5) in which subcutaneous AKR tumors were cured by the combination therapy were re-challenged on day 90 with one-fifth the number of AKR cells implanted in the contralateral hemisphere. As control, age-matched (3 months) naive mice were given the same challenge, i.e., the same dose of tumor cells (n = 5). (D) Growth of rechallenged AKR tumors in cured mice and naive mice. The results are presented as the mean ± SEM (n = 5). (E) Kaplan-Meier survival analysis. One-way ANOVA followed by Dunnett’s test (A), Student’s t test (C and D), and log-rank analysis (E) were used to determine the statistical significance of differences (∗∗p < 0.01; ns, not significant).