Transfer of antitumor immunity with ribonucleic acid-containing spleen extract of immunized animals

Abstract

Ribonucleic acid-containing spleen extract (i-extract) was prepared from the spleens of C57BL/6 mice immunized with mammary carcinoma Ca755. The i-extract contained a factor which could transfer antitumor immunity into the recipient mice, since the tumor growth was significantly retarded if mice received IP injections of i-extract at the same time as or at 6 days after tumor transplantation. Little or no inhibition of tumor growth was observ, ed in mice which received injections of i-extract 6 days prior to tumor transplantation.Tumor growth was also inhibited in mice which had received live attenuated strain (SER) Salmonella enteritidis by IV injection 6 days prior to the tumor transplantation, whereas no growth inhibition was observed in mice which were treated by injection of live SER strain of S. enteritidis simultaneously with the tumor transplantation.Tumor growth was synergistically inhibited if mice received live SER by injection 6 days prior to and i-extract 6 days after tumor transplantation, and an extended survival was observed.

Enhancing effects of mini-cells prepared from Salmonella typhimurium on anti-tumor immunity in sarcoma 180-bearing mice

“…We reported previously that whole cells of an attenuated strain of Salmonella enteritidis enhanced the anti-tumor immunity of hosts that had been given transplants of mammary carcinoma [3]. We also reported that mini-cells of an avirulent strain of Salmonella typhimurium enhanced cellular but did not humoral immunity, and that the enhancing activity of mini-cells might be independent of the lipopolysaccharide of Salmonella cells [5].…”