Immunological Block to Synthetic α-Melanocyte-stimulating Hormone: Melanocyte Interaction by Antibodies Isolated from Cell-Column Immunoadsorbents

Antibodies to formalin-fixed, syngeneic melanoma cells were prepared in mice, purified by immunoaffinity chromatography, and tested for binding activity to viable melanoma cells. The radiolabeled antibodies detected ≃9 × 106 melanoma antigenic sites/cell. The calculated average association constant (Ka) for the antibody population was 7 to 10 × 107 m−1. The antibody was shown to block the binding of melanocyte-stimulating hormone in competitive cell surface binding studies. Results are discussed conceptually in terms of the potentially important role that the humoral immune response may play in the phenomenon of tumor progression.