Factors in the sera of tumor-bearing mice modifying the charge of immune cells

Abstract

The mean electrophoretic mobility (EPM) of normal C3H spleen cells is significantly slackened (by approximately 15%) when the cells are incubated for 0.5 h at 37 degrees C with serum from slow-growing tumors (VMM2 and VMM1 tumors). On the contrary, it is not modified when the cells are incubated with serum from fast-growing tumors (RV2 or VFM1 tumors). VMM2 serum heated at 56 degrees C induces the same phenomenon. Incubation at 4 degrees C with VMM2 serum does not induce any change in spleen cell EPM. VMM2 and VMM1 sera seem to be essentially active on T cells. Indeed, no effect is observed with cells from 'nude', thymectomized, bone marrow-reconstituted C3H mice, or with the B cell-enriched fraction after nylon wool separation of normal spleen cells. A significant EPM decrease is only observed after serum incubated with the T cell-enriched fraction. Polyacrylamide gel electrophoresis shows that these sera exhibit an increase in the content of different protein groups. These phenomena suggest that the reduction of negative charge of lymphocytes after interaction with some tumor sera (VMM2 and VMM1 sera) might help establish tumor cell-lymphocyte contact and thus explain the slow growth rate of these VMM2 and VMM1 tumors.