Macrophage inflammation protein-3α (MIP-3α) is a chemokine expressed in inflamed tissue and capable of inducing migration of immature dendritic cells (DCs) or Langerhans cells. We postulated that conditioning vaccination sites with MIP-3α might enhance the efficacy of subsequently administered DC-based cancer vaccines. Our results demonstrate that subcutaneously injection of irradiated tumor cells expressing MIP-3α induces substantial cell infiltration to the injection site. Vaccination of irradiated tumor cells expressing MIP-3α followed by DCs pulsed with irradiated tumor cells can effectively suppress tumor growth in animals, which is significantly better than vaccination with irradiated MIP-3α-producing tumor cells or DCs pulsed with tumor cells alone. The protective effect was most evident when the MIP-3α-producing tumor cells and DC-based vaccines were injected at the same site. These results support the notion that this combination vaccination strategy might generate a more effective immune response to suppress the growth of tumor cells in animals.
