Immunological properties of malignant and nonmalignant sublines of L-cells.

Selection for immunoresistance and malignancy of nonmalignant sublines of L-cells resulted in the procurement of malignant LS-cells which grew successfully and killed 70% of syngeneic C3H mice. Preliminary inoculation with L-cells protected 30% of the animals from subsequent challenge by LS-cells. The L- and LS-cells had the following immunological properties in common: (a) sensitivity to the complement lytic action; (b) the ability to absorb lymphocytes on their surfaces; (c) the ability to affect the immune reactions by metabolic products; and (d) sensitivity to cytotoxicity of macrophages. However, LS-cells appeared to be more resistant to lysis by alloimmune T-lymphocytes and were much more resistant to lysis by natural killer cells from Wistar rats and athymic nude mice. In syngeneic recipients, the immune response to L- and LS-cells, evaluated by the in vitro cytotoxicity test, was equal for both types of cells. Only a partial cross-reactivity between L- and LS-cells was noted in cellular and humoral immune reactions.