Effect of OK-432 on immunization with mitomycin-C-treated L1210 cells.

The pretreatment of B6D2F1 mice with OK-432 alone was not so effective to retard the growth of L1210 leukemia, and the leukemic cell was poorly immunogenic in the mice. However, when OK-432 was given by ip injection in combination with mitomycin-C-treated L1210 cells, the growth of L1210 leukemia was significantly retarded and some mice did not "take" the leukemia. Meanwhile, BCG was also effective in this respect. Differences in properties as an immunopotentiator between OK-432 and BCG were suggested by the experiments of in vitro cytotoxicity test of spleen cells.