Inhibition of peritoneal dissemination of murine colon carcinoma cells by administrating retrovirus harboring IL-2 gene

We have examined the antitumor effect of the retrovirally expressed interle ukin-2 (IL-2) gene in murine colon carcinoma cells (Colon 26) on a dissemin ated model within the peritoneal cavity. Intraperitoneal injection of IL-2- producing Colon 26, but not wild-type cells, into syngeneic mice did not ca use animal death and conferred T-cell-dependent tumor-specific protective i mmunity on the inoculated mice. Direct administration of the retrovirus har boring IL-2 gene into the peritoneal cavity of the mice that had intraperit oneal tumor of wild-type cells significantly prolonged the survival of the mice compared with that of the mice that received control retrovirus. In th e surviving mice treated with the retrovirus we also observed the induction of protective immunity with tumor specificity. Integrated retrovirus DNA w as not detected in any organs examined. Thus, in vivo IL-2 gene transfer by retrovirus enabled tumor-bearing mice to generate antitumor immunity witho ut unnecessary retroviral insertion into host genome.