The effects of specific antibody-complement-mediated cytotoxicity on transformed and untransformed Syrian hamster cells.

Antibodies were produced against 220,000-molecular-weight proteins of Syrian hamster embryo cells. The antiserum containing these antibodies is capable of immunologically staining the surfaces and a fibrillar network around untransformed Syrian hamster embryo cells. The staining is removed by adsorption of the antiserum with Syrian hamster embryo cells and by mild trypsin treatment. Several lines of neoplastically transformed Syrian hamster embryo cells isolated and cloned after treatment with chemical carcinogens show little or no immune staining. Adsorption of the antiserum with certain transformed cells does not significantly reduce the immune staining of untransformed Syrian hamster embryo cells. The immune antiserum, in the presence of complement, is selectively cytotoxic to the untransformed Syrian hamster embryo cells. However, the transformed lines show resistance to this treatment. Analysis of the lactoperoxidase-catalyzed, iodinated cell surface proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals that the transformed lines have either no detectable labeling or a marked reduction in the labeling of 220,000-molecular-weight proteins that are major iodinatable cell surface proteins on untransformed Syrian hamster embryo cells.