SENSITIZING T-LYMPHOCYTES FOR ADOPTIVE IMMUNOTHERAPY BY VACCINATION WITH WILD-TYPE OR CYTOKINE GENE-TRANSDUCED MELANOMA

Background: For the relatively nonimmunogenic B16-F10 murine melanoma, it has been found that genetically engineered expression of granulocy te-macrophage colony-stimulating factor (GM-CSF) but not interleukin ( IL)-2, IL-4, or interferon-gamma (IFN-gamma) resulted in a vaccine tha t could induce resistance to rechallenge. Because T cells from lymph n odes draining the sites of some progressive tumors can mediate tumor r egression after in vitro activation, it seemed possible that even appa rently nonimmunogenic melanoma cells might induce similar preeffector cells in the vaccine-draining lymph nodes (DLNs), Methods: C57BL/6 mic e were vaccinated with B16-F10 cells that were either unmodified or ge netically modified to produce IL-2, IL-4, GM-CSF, or IFN-gamma. DLNs w ere harvested 10 days after vaccination for adoptive immunotherapy (AI T). The DLN cells were activated with bryostatin 1 and ionomycin (B/I) , expanded for 10 days in culture, and transferred to mice with 3-day pulmonary metastases. Pulmonary nodules were counted 14 days after AIT . Results: Adoptive transfer of expanded DLN lymphocytes sensitized by inoculation of WT B16-F10, or IL-4, CM-CSF, or IFN-gamma expressing c ells significantly reduced pulmonary metastases. Despite the spontaneo us regression of IL-2-transduced B16-F10 tumors, DLN from mice inocula ted with IL-2 producing B16 cells had little or no antitumor activity, Conclusions: E16-F10 vaccination strategies that apparently do not in duce systemic immunity can effectively sensitize DLN preeffector cells .