Peanut lectin agglutinin and alpha-lactalbumin. Binding and immunohistochemical localization in breast tissues.

We analyzed 31 breast lesions immunohistochemically for alpha-lactalbumin (ALA) production and T-antigen presence as defined by peanut lectin agglutinin (PNA). Most cases of well-differentiated infiltrating carcinomas (14 of 17) and of poorly differentiated carcinomas (two of four) showed positive immunoreactivity for ALA; ALA was also localized in three cases of normal breast tissues, in two fibroadenomas, and in five intraductal carcinomas. The PNA binding pattern was primarily along the luminal cytoplasmic cell membrane in normal breasts and in fibroadenomas. We saw both cell membrane and cytoplasmic binding in carcinomas. In seven cases of primary and metastatic carcinomas to axillary lymph nodes, both primary and metastatic tumors expressed T antigen and produced ALA. These studies indicate that ALA can be used as a diagnostic marker in breast carcinoma and that the PNA binding pattern in normal and benign breast tissues is primarily at the luminal cytoplasmic cell membrane, whereas both cytoplasmic and cell membrane binding are present in carcinomas. The production of ALA does not appear directly related to T-antigen expression or to metastatic disease.