Cell-surface antigens from human breast tumor cells.

Biochemical and immunologic studies on breast cancer with the use of cells from a human ductal cell carcinoma, BOT-2, were initiated. Antigens were extracted from the cells by mild sonication and purified by gel filtration chromatography. Only one of the three peaks from gel filtration chromatography reacted with antiserum prepared against whole BOT-2 cells. Analysis by polyacrylamide gel electrophoresis of the BOT-2 cell extract revealed many protein bands, whereas analysis of the antibody-reactive peak after gel filtration chromatography revealed fewer protein bands. Immunologic tests to identify human serum antibodies against BOT-2 cells or cell extracts were performed by fixed cell immunofluorescence, living cell membrane immunofluorescence, and indirect hemagglutination. Depending on the test, the sera from women with diagnosed, untreated mammary cancer were positive in 45--80% of the cases, whereas the sera from women without apparent breast diseases (controls) were positive in only 5--10% of the cases. The results suggested that the antigens from the BOT-2 cells will be useful in understanding the processes involved in human mammary neoplasia.