MURINE COLON-CARCINOMA CELLS ENGINEERED TO PRODUCE HUMAN INTERLEUKIN-2 INDUCE TUMOR-SPECIFIC ANTITUMOR RESPONSE

Murine colon carcinoma cells (colon 26) transduced by a retrovirus vec tor with the human interleukin-2 (IL-2) cDNA were studied for their tu morigenicity. Although cell growth in vitro was not affected by integr ation of the IL-2 gene, s.c. tumors of IL-2-producing colon 26 cells ( Hi) in syngeneic mice regressed spontaneously after producing small ma sses. Histological examination of the sites of tumor rejection reveale d predominant infiltration of macrophages around the tumor necrotic ma ss. Subsequent challenge with parent colon 26 cells, but not with Meth A cells (fibrosarcoma of the same genetic background), did not result in tumor formation in mice which had been protected against H2 cells. Inoculation of H2 cells into syngeneic nude mice resulted in tumors w ith a retarded growth rate. Taken together, T cell-dependent, tumor-sp ecific immunity is obtained by local IL-2 secretion around colon tumor s, and this experimental animal model gives us a clue(s) for investiga ting host anti-tumor responses by cytokine production. (C) 1996 Wiley- Liss, Inc.