Affinity cytotoxicity of tumor cells with antibody-glucose oxidase conjugates, peroxidase, and arsphenamine.

Selective cytotoxicity was accomplished in two antibodytumor cell models with antibody-glucose oxidase conjugates (Ab-GO) followed by treatment with horseradish peroxidase (HRP) and arsphenamine. The two cell models used were hapten [2,4,6-trinitrophenyl (TNP)]-substituted HeLa and HEp-2 cells with specifically purified antihapten (TNP) antibody and human colonie carcinoma cells (HT-29) with immunoglobulin G anti-carcinoembryonic antigen antibody. Brief treatment of TNP cells with antiTNP antibody conjugated to glucose oxidase (0.07 to 70 /ig/ml) followed by culture in medium with HRP (50 fig/ml) and arsphenamine ( 1to 10/ng/ml) resulted in zero to 100% cell killing when compared with controls in a microcytotoxicity assay. Cytotoxicity was reduced or absent when (a) any of the three components (Ab-GO, HRP, or arsphenamine) were omitted; (b) cells not substituted with TNP were used; or (c) free hapten (dinitrophenyl-lysine) inhibited Ab-GO binding to TNP cells. Affinity cytotoxic ity (73 to 90%) was also seen in HT-29 cells treated with anti-CEA antibody conjugated to glucose oxidase followed by treatment in HRP and arsphenamine (1 to 10 jug/ml). CEA, extracted from malignant ascitic fluid with perchloric acid, partially inhibited the cytotoxic action of the Ab-GO system, and normal goat immunoglobulin G-glucose oxi dase caused significantly less killing, showing the selectivity of the reaction.