PERTINENCE OF SURFACE MEMBRANE CHANGES IN SPONTANEOUSLY AND VIRALLY TRANSFORMED CELLS TO THE BALANCE BETWEEN TUMORIGENICITY AND IMMUNE REJECTION

Abstract

Spontaneously transformed highly tumorigenic AL/N strain mouse cells and their SV40 virus transformed clonal derivatives were compared. Glycoproteins were labeled by various metabolic precursors (amino acids, glucosamine, mannosamine, etc.). The flow of such labels into various subcellular components was followed. Cell surface membranes were obtained and the components of these membranes were separated by polyacrylamide gel electrophoresis. The biosynthesis of a prominent glycoprotein component with an apparent molecular weight of 180 K dalton was reduced in the SV40 transformed cells, when all the different kinds of cells were grown in their logarithmic phase. Three types of SV40 specific antigens were detected by immunologic assays: (1) T antigens, (2) tumor specific surface antigens (TSSA), and (3) tumor specific transplantation antigens (TSTA). A rapid and sensitive microassay for TSSA guided the development of a mild and efficient detergent (Triton X-100) solubilization technique, and the purification of the antigens that appear to co-purify in various procedures. The antigens expressed on the cell surface that are responsible for immunologic recognition and rejection of the SV40 transformed cells represented a very minor fraction of the cell surface membrane components. The microassay for TSSA allowed partial purification and characterization of the SV40 specific cell surface antigen (s). The(se) SV40 specific cell surface antigen (s) in the AL/N strain mouse functionally opposes cellular tumorigenicity.