Immunotherapeutic effect of allogeneic tumor cells on the growth of autochthonous 3-methylcholanthrene-induced sarcomas in rats.

The tumor-inhibitory effect of injections of allogeneic tumor cells was observed. Established autochthonous sarcomas induced in the subcutaneous tissue of rats by 3-methylcholanthrene (MCA) were treated with immunization by using allogeneic Hirosaki sarcoma cells. When MCA-induced sarcomas grew to approximately 1 cm in mean diameter, Hirosaki sarcoma cells were inoculated into various tissues of primary tumor-bearing rats. Immunizing procedures consisted of intraperitoneal and subcutaneous injections in one experimental group, and of intradermal and intraperitoneal injections in another. Significantly inhibitory effect on the growth of autochthonous sarcomas was observed in the initial stage up to 2 cm in diameter as compared with that of control sarcomas. No significant inhibition was seen in the course of the growth of sarcomas larger than 2 cm in diameter. This results may indicate that immunotherapy by using allogeneic tumor cells should be considered to be valuable for the treatment of human cancer.