Immunoelectronmicroscopic Analysis of Surface Antigens Common to Mycobacterium bovis (BCG) and Tumor Cells2

The presence of cell-surface antigens on line10 hepatocarcinoma cells was demonstrated by immunoelectronmicroscopy (IEM) with the use of xenogeneic and syngeneic tumor-specific antibody and syngeneic BCG-induced antibody. This confirmed that in addition to tumor-specific antigen(s) there are common antigens between line-10 hepatocarcinoma cells and BCG organisms. The specificity of this cross-reactivity was further supported by blocking experiments and absorption of the specific antibody to BCG organisms, with subsequent IEM of the BCG and loss of reactivity to tumor cells. Complement- dependent serum cytotoxicity was correlated with the IEM assay. Cross-reactivity of the BCG-specific antibody with the surface of cells of a human melanoma culture grown from an excised subcutaneous melanoma was also demonstrated by IEM.