INDUCTION OF T-CELL-DEPENDENT ACQUIRED-IMMUNITY IN SYNGENEIC MICE BY THE COMBINED EXPRESSION OF INTERLEUKIN-4 AND GRANULOCYTE MACROPHAGE-COLONY-STIMULATING FACTOR GENE IN MURINE COLON-CARCINOMA CELLS

The inoculation of cytokine-producing tumor cells into syngeneic anima ls can produce antitumor effects. We previously reported that injectio n of a mired population of murine colon carcinoma (Colon 26) cells tra nsduced with interleukin-4 (IL-4) gene with granulocyte macrophage-col ony stimulating factor (GM-CSF) gene developed subcutaneous tumors in syngeneic mice, but these tumors thereafter regressed spontaneously (O ncology 1997;54:69-73). In this study, we found the generation of tumo r specific acquired immunity in the mice which had rejected the tumors of a mixed population of IL-4 and GM-CSF producer cells, and that the immunity was mediated by mature T cells. Moreover; local secretion of both IL-4 and GM-CSF in the vicinity of tumors was found to be crucia l for this rejection. These data suggest that enhanced host defense br ought about by the combined expression of IL-4 and GM-CSF genes in tum or cells is a potential therapeutic strategy.