TC-1 tumors were effectively treated by peptide + CpG–containing vaccines combined with IL-2 during T-cell reconstitution by HPE after BMT. (A) Mice underwent BMT as described in Figure 1. On day 14 after BMT, mice were injected with TC-1 tumor cells, which express the E7 protein. On days 17, 20, 23, and 31 after BMT, the mice were vaccinated with E7_49-57 + CpG + IFA vaccines or the negative control peptide NP_366-374 plus CpG in IFA. IL-2 was administered to both groups on days 24 to 26 and days 32 to 35 after BMT. When CD8⁺ T-cell responses were measured by ICCS assay on day 36 after BMT in E7_49-57–vaccinated mice, E7_49-57–specific CD8⁺ T-cell responses were detected. Minimal responses against the negative control peptide NP_366-374 were detected in E7_49-57–vaccinated mice. Tumor-bearing mice vaccinated with NP_366-374 did not generate E7_49-57–specific CD8⁺ T-cell responses. The numbers on the plots are the percentages of CD8⁺ T cells from mice receiving the indicated vaccines that produced IFNγ in response to ex vivo stimulation with the indicated peptides. (B) Mice underwent BMT and 14 days after BMT the mice were injected with 50 000 TC-1 tumor cells. On days 17, 20, 23, and 31 after BMT, the mice were vaccinated with either E7_49-57 + CpG in IFA or the negative control peptide NP_366-374 plus CpG in IFA. Both groups received IL-2 as described in (A). Aside from the different peptides, both groups were treated identically. A statistically significant difference in tumor size between the 2 groups occurred at the indicated (*) time points (P < .001, n = 14 mice per group). (C) In the same mice described in (B), survival was increased in mice that received vaccines containing E7_49-57 compared with mice that were treated identically except that their vaccines contained the negative control peptide NP_366-374 (P < .001, n = 14 mice per group). (C) also shows the survival of post-BMT mice that were injected with TC-1 cells and then either treated with IL-2 alone on days 24 to 26 and days 32 to 35 after BMT or left untreated (IL-2, n = 11; BMT alone, n = 11). (D) Mice underwent BMT and then received either a CD8-depleting antibody or an isotype-matched control antibody. Mice were injected with 50 000 TC-1 tumor cells 14 days after BMT. Both CD8-depleted mice and mice that were not depleted were vaccinated with E7_49-57 + CpG in IFA and treated with IL-2 as in (A). Depletion of CD8⁺ cells led to increased tumor growth (D) and decreased survival (E) (CD8 depleted, n = 11; not depleted, n = 12). In (D), a statistically significant difference in tumor size (P < .001) between the 2 groups occurred at the indicated (*) time points.