Vaccination with tumor cells pulsed with foreign peptide induces immunity to the tumor itself.

EMT-6 mammary carcinoma and B16 melanoma (B16M) cells are lethal and barely immunogenic in syngeneic BALB/c and C57BL/6 mice, respectively. We show that mice vaccinated with tumor cells pulsed with a MHC class I-restricted peptide develop a T cell response, not only to the peptide, but also to the unpulsed tumor. These mice display protective immunity against the unpulsed tumor, and their T cells adoptively transfer tumor-specific protection to immunodeficient SCID mice. Our data have implications for cancer vaccine strategies. Grafting a single well-defined foreign peptide on tumor cells might suffice to trigger anti-tumor immunity.