PEPTIDE-PULSED DENDRITIC CELLS INDUCE ANTIGEN-SPECIFIC, CTL-MEDIATED PROTECTIVE TUMOR-IMMUNITY

Cytotoxic T lymphocytes (CTLs) are a critical component of the immune response to tumors. Tumor-derived peptide antigens targeted by CTLs ar e being defined for several human tumors and are potential immunogens for the induction of specific antitumor immunity. Dendritic cells (DC) are potent antigen-presenting cells (APCs) capable of priming CTL res ponses in vivo. Here we show that major histocompatibility complex cla ss I-presented peptide antigen pulsed onto dendritic APCs induces prot ective immunity to lethal challenge by a tumor transfected with the an tigen gene. The immunity is antigen specific, requiring expression of the antigen gene by the tumor target, and is eliminated by in vivo dep letion of CD8(+) T cells. Furthermore, mice that have rejected the tra nsfected tumor are protected from subsequent challenge with the untran sfected parent tumor. These results suggest that immunization strategi es using antigen-pulsed DC may be useful for inducing tumor-specific i mmune responses.