Human mammary epithelial antigens (HME-Ags) in the circulation of nude mice implanted with a breast tumor and non-breast tumors.

Human mammary epithelial antigens (HME-Ags) obtained from the membrane of the human milk fat globule (HMFG) were tested for their possible role as breast tumor markers. Specific antisera raised against HME-Ags were used to monitor plasma concentrations of these antigens in nude mice implanted with a human breast tumor. The level of plasma HME-Ags, determined by radioimmunoassay, was significantly higher in animals transplanted with a human breast tumor (mean +/- standard error; 687 +/- 184 ng/ml) than those with other types of human tumors (colon carcinoma: 50 +/- 29; lung carcinoma: 82 +/- 78; medulloblastoma: less than 30; and Wilson melanoma: less than 30) and healthy control animals (49 +/- 22). Removal of the breast tumor resulted in a significant drop of HME-Ags level to "background" values, suggesting that animals with the breast tumor did release into the circulation HME-Ags which could be possibly used as breast-tumor markers in breast tumor diagnosis.