Monoclonal antibody E6G6 recognizes glycolipids as a differentiation antigen in Shope carcinoma cells

Monoclonal antibody E6G6 preferentially reacted with well differentiated and non-tumorigenic Shope carcinoma cell lines but hardly reacted with undifferentiated and tumorigenic lines as determined by enzyme-linked immunosorbent assay, cytofluorometry and the complement dependent cytotoxicity test. Immunohistochemical analysis of the primary carcinoma tissue revealed that the antibody intensely stained keratinizing carcinoma cells with marked shrinkage whereas it did not stain normal epidermal keratinizing rabbit cells or benign tumor (Shope papilloma) cells, suggesting that the antigen expression in vivo was closely correlated with terminal differentiation of the carcinoma cells. Thin layer chromatography immunostaining revealed that the antigen was comprised of several neutral glycolipids and that differentiated cells contained about ten times more antigen than undifferentiated cells.