Lymphocyte Stimulation by a Mammary Carcinoma Associated Glycoprotein

A glycoprotein was isolated from 3M KCl extracts of mammary carcinoma. Addition of an optimal amount of the carcinoma associated glycoprotein induces proliferation of both peripheral blood lymphocytes from normal donors and from patients with mammary carcinoma. RNA-dependent DNA-polymerase levels were found to be markedly increased in glycoprotein-untreated lymphocytes from patients with mammary carcinoma and in glycoprotein-treated lymphocytes of both normal donors and tumor-bearing patients. A factor ("Blocking Factor") was eluted at pH 3.1 from the cell membrane of the mammary carcinoma cells. Addition of an optimal amount of this factor inhibits the glycoprotein induced stimulation of the RNA-dependent DNA-polymerase activity in glycoprotein-treated lymphocytes of both normal donors and tumor-bearing patients.