Sensitivity of persistent leukemic cells to NK- and CTL-mediated killing. (A) Sensitivity to CTL-mediated killing of DA1-3b leukemic cells. Mice were vaccinated with leukemic cells that had been transduced with CXCL10 (DA1-3b/CXCL10), IL-12 (DA1-3b/IL-12), or with control empty plasmid (DA1-3b/Zeo), and CTLs were isolated. (B) Mice were vaccinated with irradiated DA1-3b/IL12 cells, following which CTLs were isolated and tested for their ability to kill leukemic cells that had persisted in other animals for 1 month (DA1-3b/d35), 3 months (DA1-3b/d90), and 1 year (DA1-3b/d365). (C) Sensitivity to NK cell-mediated killing of DA1-3b leukemic cells, YAC-1, and EL4 cells. NK cells were isolated from mice vaccinated with DA1-3b/CXCL10, DA1-3b/IL12, or DA1-3b/Zeo. (D) NK cells were isolated from mice vaccinated with irradiated DA1-3b/CXCL10 cells and tested for their ability to kill leukemic cells that had persisted in other animals for 1 month (DA1-3b/d35), 3 months (DA1-3b/d90), and 1 year (DA1-3b/d365), in the presence of anti-B7H1–blocking antibodies, anti-B7.1–blocking antibodies, or control isotypes. CMA was added to DA1-3b cells to block the perforin/granzyme cytolytic pathway (CMA + DA1-3b). (E) Flow cytometry analysis of B7-H1 expression in NK cells isolated from immune infiltrates in matrigel at the vaccine site. The bold line represents anti-B7-H1 labeling, and the thin line represents the control isotype. All experiments were performed in quadruplicate and repeated at least 3 times. Data represent mean and SD.