[Successful adoptive immunotherapy with OK432-inducible activated natural killer cells on tumor-bearing mice].

We had demonstrated that the NK cell mediated cytotoxicity of murine spleen cells could be augmented by in vivo prime and subsequent in vitro challenge with the streptococcal preparation OK432, and the cell surface phenotype of induced killer cells was Thy 1+, asialo GM1+, suggesting the activated NK cells (OK-NK cell). The culture supernatants of spleen cells with OK432 possessed the activity of IL-2 and IFN-gamma, and the IL-2 played a major role to induce the OK-NK cells via the production of IFN-gamma. In this study, we examined the effect of adoptive transfer of OK-NK cells on tumor-bearing mice. The mice were implanted SP2 myeloma cells intraperitoneally (i.p.), or C26 colon adenocarcinoma cells subcutaneously (s.c.) to make the models of peritonitis carcinomatosa or solid tumor, and the OK-NK cells were transferred i.p. or i.t., adoptively. By the adoptive transfer of OK-NK cells, the 92% of mice bearing SP2-tumor had be cured. The tumor growth of C26-solid tumor was inhibited, and the survival rate of mice bearing C26-tumor was increased, significantly. The intratumoral remnants of 125I-labelled OK-NK cells were 61.27 and 8% after intratumoral transfer, respectively. By multiple transfer of OK-NK cells the anti-tumor effect was more augmented than that of a single transfer. Thus we recognized the anti-tumor effect of adoptive transfer of OK-NK cells on tumor-bearing mice, and suggested that OK-NK cells could be useful for the therapy of cancer patients.