Blood group-like activity released by human mammary carcinoma cells in culture

Abstract

TUMOUR cells synthesise and release antigenic membrane associated components which circulate either in a free state or complexed with host immunoglobulins^1–5. A membrane derived N-like glycoprotein, which inhibited Vicia graminea lectin haemagglutination, has been demonstrated in serum and ascites fluid of mice bearing the Ha subline of TA₃ murine mammary adenocarcinoma⁶. Springer et al.⁷ have shown that M and N blood group reactive substances were present in both benign and malignant lesions of the human breast. But, T-like Arachis hypogaea reactive substances were only found in malignant breast tissue and not in benign tumours or healthy breast tissue⁷. Isolation and long term cultivation of a human mammary tumour cell line. BOT-2 was recently reported⁸. Immunological tests indicated that women with diagnosed mammary cancer had circulating antibodies that reacted with these cells⁹ and induced cell surface shedding¹⁰. Here we report the use of blood-typing antisera and lectins to characterise the proteins synthesised and spontaneously released from BOT-2 cells growing in defined medium. To our knowledge this is the first demonstration of M, N, T, Tn erythrocyte-like glycoproteins being spontaneously shed from human epithelial tumour cells in culture.