Functional changes of macrophages from polyoma tumor-bearing mice

CBA mice were inoculated with different doses of polyoma tumor cells. The PHA response of spleen cells from tumor-bearers was decreased but the spontaneous incorporation of 3H-leucine was increased. PHA-induced cytotoxicity of spleen cells was increased only in tumor-bearers. The expression of Fc receptors showed a slight increase on adherent cells from spleen and peripheral blood mononuclear cells under suboptimal conditions for EA rosette formation (small amount of antibody for coating the erythrocytes). The non-specific esterase activity was assayed in an extract of peritoneal macrophages and the elevated activity with isoenzymes was seen in a group of tumor-bearers. The results suggest a functional alteration of macrophages in polyoma tumor-bearing mice.