Vaccinated leukemic mice have spleen features comparable with naive mice. Spleen immunohistochemistry of (A) control pac-AML–vaccinated leukemic mouse; (B) IL12-AML–vaccinated leukemic mouse; and (C) naive SJL mouse. The spleen from pac-AML–vaccinated mouse is almost completely infiltrated by Gr-1–positive cells and has very few residual B220 (B cells) and CD4/CD8 (T cells) positive cells. In contrast, the distribution of myeloid and lymphoid cells in the IL12-AML spleen is comparable with naive spleen.