Effect of splenectomy and immuno-potentiator on tumor-bearing mice

To determine the effect of splenectomy on tumor growth, the immunological role of the spleen was studied at various time intervals following subcutaneous implantation of MH-134 hepatoma cells into syngeneic C(3) H/He mice. Both tumor neutralizing activity and PHA-suppressor cell activity were generated. the former reached a maximum on the 28th day of implantation, and belonged to Lyt-1(+)2(-)T cells. The latter appeared on the 3rd day, decreased once, and increased again. Mainly, this suppres-sive activity was found in Lyt-1(+)2(-)T cells on the 3rd day and in nylon-wool-adherent cells after the 14th day. Splenectomy or sham splenectomy (sham ope) was performed on the 3rd day of implantation. There was no significant difference in tumor growth between the groups. Immunotherapy with lentinan effectively suppressed tumor grouth both in the tumor-bearing mice that had splenectomy and in those that had sham ope, with no significant difference in tumor growth between the two groups. Therefore, the effectiveness of splenectomy on tumor growth might be difficult to evaluate, since these opposite activities are simultaneously induced in the spleen of tumor-bearing mouse.