Posttransplantation vaccination significantly increased frequencies and absolute numbers of tumor-reactive CD8 T cells in the spleens of treated mice. Tumor-bearing A/J mice received transplants of syngeneic BM cells plus 6 × 106 T cells from naive (Naive T) or pre-vaccinated (Sen T) donor mice. Some mice were treated on days 2, 7, and 14 after HSCT with the AGN2a-4P vaccine (Vac). On days 7, 11, and 18 after HSCT (5 days after first, 4 days after second, and 4 days after third vaccine), spleens were harvested and CD8 T cells isolated by immunomagnetic sorting. The CD8 cells were assayed in IFN-γ ELISPOT assays with tumor cell stimulators to determine tumor-reactive IFN-γ–secreting cell frequencies and absolute numbers. The data are from 1 of 3 replicate experiments, and the CD8 T cells were isolated from the pooled splenocytes of 3 mice. **P < .01; ***P < .001 when Sen T results were compared with Sen T + Vac results at the indicated times.
