A simple and highly reproducible mouse colonic cancer model with mesenteric lymph node (MLN) metastasis was established by injecting COLON-26 tumor cells into lymphatic nodules in the tip of vermiform appendix of BALB/C mice. In this model, antitumor effect of orally administered OK-432 was examined. OK-432 was given orally at three different periods: before injection of COLON-26 cells (Protocol-A), early after injection of COLON-26 cells (Protocol-B), and late after injection of COLON-26 cells (Protocol-C). As a result, MLN metastasis was significantly suppressed and survival rate was significantly improved in every protocol as compared to mice without OK-432 administration. Then, in vivo anti-tumor activities of MLN cells and splenic lymphocytes were evaluated by Winn assay. Tumor neutralizing activity against syngenic COLON-26 cells was induced in the MLN cells after OK-432 administration and the effector cells were found in CD4-positive T lymphocytes because MLN cells treated with anti-L3/T4 and anti-LFA plus complement lost their anti-tumor efficacy. In conclusion, oral administration of OK-432 appears to be an effective immunotherapy against colonic cancer especially in the prevention and the treatment for MLN metastasis.
|Number of pages||9|
|Journal||Nippon Geka Gakkai zasshi|
|Publication status||Published - 1995 Oct|
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