IDENTIFICATION OF IMMUNOREACTIVE TISSUE KALLIKREIN IN HUMAN DUCTAL BREAST CARCINOMAS

Various proteases have been shown to be present in malignant breast ti ssue. Although the question of the involvement of tissue kallikrein, a serine protease, int he pathophysiology of tumours has been raised, t he presence of this enzyme in human breast carcinoma has so far not be en examined. In the present study, both neoplastic and normal human br east are scanned by immunocytochemistry for the presence and cellular localization of tissue kallikrein. In the healthy breast, tissue kalli krein was observed as a deposit of immunoreactive material that locali zed in the apical portion of duct cells. In the malignant breast tumou rs surveyed, the enzyme was observed only in ductal carcinomas, wherea s lobular carcinomas were devoid of immunostaining. In ductal carcinom as, the immunoreactivity for tissue kallikrein appeared to be associat ed with gradations of malignancy, being absent in dedifferentiated tum ours. The presence of tissue kallikrein in malignant breast tumours po ses the question of the role of this enzyme in malignant breast tissue . The enzyme may participate within the tissue either in proteolytic p rocesses (it has been shown to activate procollagenase) or by enhancin g vascularity or mitogenicity by the generation of kinins.