Cardiotoxin administration recruits antigen-presenting cells and converts nonimmunogenic, unfused antigen into a protective vaccine. (A) Cardiotoxin alone-treated (6.8 μg by intramuscular injection) quadriceps were collected, cryo-fixed, sectioned, and stained for hematoxylin and eosin. Further identification of infiltrated cells was performed by immunostaining tissue sections with cell-specific markers for DCs (CD11c) and monocytes/macrophages (F4/80; representative of 6 quadriceps analyzed). (B) Ten syngeneic BALB/c mice per group were immunized with DNA vaccines encoding chemokine-fused (MCP3-sFv) or free antigen (sFv) plus cardiotoxin and challenged with lethal tumor as in Figure 1. The data are representative of 2 identical experiments.