Reactivity of a monoclonal antibody recognizing an estrogen receptor regulated glycoprotein in relation to lectin histochemistry in breast cancer.

We have raised monoclonal antibodies against human milk fat globule membrane antigens and previously shown that one of them, called III D 5, recognises a glycoprotein associated with estrogen receptor activity of breast cancer. In immunoblotting it was shown that the molecule in human milk exclusively stained with III D 5 also binds peanut agglutinin (PNA) and Ricinus communis. In this study we correlate the staining of III D 5 and binding of lectins to tissue sections fixed in formalin and embedded in paraffin. Similar reactions were seen only with III D 5 and PNA. Our results suggest that III D 5 and PNA detect overlapping antigenic epitopes in mammary carcinoma. This is in keeping with previous results that PNA or III D 5 reactivity is correlated with estrogen receptor status of breast cancer.