Selective Reduction of Human Tumor Cell Populations by Human Granulocytes in Vitro¹

Human peripheral blood granulocytes at a 10:1 effector cell:target cell ratio were shown by an in vitro semiquantitative staining procedure to reduce the number of human tumor cells, but not that of normal cells. Microscopic observations revealed that this selective reduction of tumor cells by granulocytes was a function of both detachment and cytolysis. The cytotoxic effect of granulocytes on the tumor cells was confirmed by a quantitative 5-[¹²⁵I]lodo-2-deoxyuridine release assay. The data indicate that human granulocytes at a relatively low effector:target cell ratio (10:1) have the capacity to recognize and destroy human tumor cells in vitro.