Figure 5. Jackson mice have an increased antitumor response and antigen-selective pressure on the tumor.

(A) Jackson and Taconic mice were injected with 2 × 10⁶ B16.SIY cells subcutaneously on day 0. Tumor growth curves show Jackson mice have significantly delayed tumor growth as compared with Taconic mice. P value = 0.0455. Significance was measured by 2-way ANOVA with Bonferroni’s post hoc test for multiple comparisons. N = 7/group. (B) Additionally, Jackson mice had significantly increased survival compared with the Taconic mice. P = 0.0065. Significance was measured by the log-rank test (Mantel-Cox test). N = 7/group. (C) Jackson and Taconic mice were injected with 2 × 10⁶ B16.SIY cells subcutaneously on day 0. Tumors were harvested at an approximate size of 200–250 mm² and analyzed by flow cytometry for GFP expression, as SIY and GFP are expressed as a fusion protein in the B16.SIY cell line (15). Jackson have a significantly lower GFP expression (P value = 0.0030) by unpaired, 2-tailed t test (n = 5 TAC, and n = 6 JAX). (D) Jackson and Taconic mice were injected with 2 × 10⁶ B16.SIY cells subcutaneously on day 0. Tumor-infiltrating lymphocytes were harvested on day 24 and analyzed by flow cytometry for CD8⁺ T cell specificity, gated on live CD8⁺ T cells. N = 2/group.