Isolation and partial purification of plasma membrane-associated antigens from human osteosarcoma (TE-85) cells in tissue culture

The plasma membrane of a cloned line of TE-85 (human osteosarcoma) cells subcultured for the last 4 years was isolated. The isolation was by hypotonic swelling, cell homogenization, and discontinuous sucrose gradient ultracentrifugation for 16 hr. Tumor-specific water-soluble antigens were identified by limited papain digestion of the isolated plasma membrane. Fractionation by diethylamino-ethyl anion-exchange column chromatography yielded antigenic fractions that inhibited the reaction of immune serum (from an unrelated patient with osteosarcoma) with the plasma membrane of TE-85 cells in tissue culture by indirect immunofluorescence test. Microimmunodiffusion confirmed the specificity of the isolated antigen against the sera of other patients with osteosarcoma. The definition of the antigen fraction may permit evaluation of antigen-antibody interaction in tumor immunity.