[Combined effect of intraperitoneally administered OK-432 and recombinant interleukin (rIL-2) against mouse tumors].

Combined effect of the streptococcal preparation, OK-432 and rIL-2, both administered intraperitoneally, was examined against Meth-A tumor, a syngeneic tumor of inbred BALB/c mice and an analysis of the effector cells also was performed. The combined treatment resulted in significant in vitro inhibition of tumor growth and increase in the length of survival of the Meth-A bearing mice. The spleen cells obtained from Meth-A bearing mice treated with both OK-432 and rIL-2 on the 12th day after the tumor transplantation were capable of lysing syngeneic Meth-A tumor cells in addition to NK-sensitive allogenic YAC-1 cells and LAK-sensitive EL-4 cells in vitro in a 4 hour 51Cr-release assay. Neither spleen cells obtained from the tumor bearing mice treated with OK-432 or rIL-2 alone, nor those obtained from normal mice treated with both agents, showed cytotoxic activity against Meth-A cells. The in vitro growth of NK-resistant allogenic P-388 was not inhibited by the spleen cells obtained from any treated mouse, with or without Meth-A tumor. In order to determine the effector subpopulation against Meth-A cells, the spleen cells obtained from the tumor-bearing mice treated with OK-432 and rIL-2 on the 12th day after tumor transplantation, were treated with either anti-Thy-1, 2 antibody plus complement, anti-asialo GM1 serum plus complement, or by adherence to a plastic plate or nylon wool column.(ABSTRACT TRUNCATED AT 250 WORDS)