Effects of injection routes of growing tumors and PSK or OK-432 on antiproliferative activity of mouse serum.

The present study examined the effects of various treatments on the antiproliferative activity of mouse serum. Its activity was estimated against the growth of EL4 tumor cells and L929 cells and against splenic blastogenesis in culture. The activity varied among mouse strains tested and among individuals in any strain. However, normal outbred NIH Swiss mice showed the highest activity among the strains and the least variation among individuals. The activity of serum from NIH Swiss mice constantly decreased 7 or 14 days after an injection of 10(6) Ehrlich or sarcoma 180 tumor cells subcutaneously in the right-hind footpad, intradermally in the right side of the chest or into the palm. Other routes, such as intraperitoneal, intravenous in the tail vein, subcutaneous in the right side of the chest and intramuscular in the left thigh, however, hardly affected the activity. The activity also decreased 7 days after an injection into the footpad of a biological response modifier such as PSK or OK-432. The antiproliferative activity of mouse serum seem to depend on macrophages but not natural killer-cell activity, because treatment with silica but not anti-(asialo-GM1) antibody totally reduced the activity. The active fraction was heat-stable (100 degrees C, 30 min) and its molecular mass was 127-140 kDa.