The binding of fluorescent-labelled concanavalin A to human breast tissue--a marker of differentiation.

Fluorescent-labelled Concanavalin A (ConA) has been applied to frozen and fixed, processed sections of normal, hyperplastic and malignant human breast tissue. No loss of binding activity occurs with fixation and the best results are obtained with Bouin's fixed material or trypsinised sections of tissue fixed in 4 per cent. formaldehyde in saline. A difference in reaction has been demonstrated between normal tissue, hyperplastic tissue and carcinomas, which is further accentuated when a lower concentration of ConA-FITC is used. Staining is consistently localised to the cell periphery in all benign tissue, the well differentiated carcinomas and some of the moderately differentiated tumours. A mixed pattern of reaction with staining of the cell periphery and cell cytoplasm is seen in some tumours, whilst many of the poorly differentiated carcinomas show cytoplasmic staining only. There is a significant correlation between the pattern of staining and the histological differentiation of carcinomas, and between the degree of reactivity and differentiation. It is suggested that any relationship ConA reactivity may have to prognosis may be strongly associated with tumour differentiation.