Chemotherapeutic drugs increase killing of tumor cells by antibody and complement.

When the ascitic forms of two antigenically distinct guinea pig hepatomas induced by diethylnitrosamine are treated in vitro with chemotherapeutic drugs, their sensitivity to killing by xenogeneic antibody plus guinea pig complement increases. The effect is dependent on drug dose, is reversible, and does not appear to be due to increased antigen expression or fixation of the early acting components of guinea pig complement.