Endocytosis of chlorambucil-bound anti-tumor globulin following "capping" in EL4 lymphoma cells.

A rabbit 7 S antibody reacting specifically with a tumor assoicated antigen on the surface of mouse EL4 lymphoma cells could form "caps" and subsequently undergo endocytosis even when the antibody was non-covalently bound to chlorambucil. As the alkylation of nuclear DNA appears to be the basis of tumor inhibition by alkylating agents like chlorambucil, facilitation of the transport of chlorambucil across cell membrane by anti-tumor antibodies might explain, at least in part, the increased tumor inhibition by cholorambucil bound anti-tumor antibodies compared to tumor inhibition by equivalent amounts of tumor antibodies or chlorambucil alone.