The localization of prolactin binding sites in human breast tissue.

An immunohistochemical method involving the application of purified human prolactin and a specific antiserum to human prolactin, followed by the peroxidase-anti-peroxidase immunoperoxidase technique, has been used to detect prolactin binding in benign and malignant human breast tissue. The use of fresh, frozen material has been found to be essential. Prolactin binding has been shown to be a consistent feature of benign breast tissue but a variation within samples has been noted which is irrespective of hyperplastic changes. Fifty six percent of breast carcinomas gave a positive reaction but heterogeneity of binding has been shown to be a significant feature. A relationship between the presence and extent of prolactin binding and good histological differentiation of the tumours has been noted. It is concluded that immunohistochemistry is a suitable method for the demonstration of prolactin binding sites in human breast tissue and can provide useful information with regard to tumour heterogeneity.