Selective complement dependent cytotoxicity was demonstrated in a hapten-substituted cell culture model system. Viable hapten substituted HeLa, Hep-2, and L cells were obtained by treatment with 10 to 300 µg/ml of 2, 4, 6-trinitrophenyl (TNP)-sulfonic acid. Binding studies with 14C-TNP-sulfonic acid showed that from 1 to 9 × 109 TNP groups were bound per cell, representing 1 to 4% of the added TNP. High affinity anti-TNP antibody was purified from the sera of rabbits hyperimmunized with TNP-bovine γ-globulin. The amount of anti-TNP Ab binding to TNP-cells was quantitated and found to be dose dependent in this range of TNP substitution. Even at the highest levels of antibody, only about 1% of TNP groups was bound by antibody. The selectivity of antibody binding to TNP-cells was established by inhibition with the hapten, ε-DNP-lysine. Anti-TNP antisera, and to a lesser extent, specifically purified anti-TNP antibody, caused complement dependent cytotoxicity of TNP-cells but not unsubstituted cells. This model system permits comparative cytotoxic antibody studies with a variety of tumor cells.

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This work was supported by National Institutes of Health Grant 5R01 CA 12626.

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