Demonstration of cytokeratins by immunoperoxidase staining in prostatic tissue

The presence and distribution of cytokeratins (CK) have been investigated using an epidermal keratin antiserum in various dilutions and the PaP (peroxidase-antiperoxidase) and avidin-biotin-peroxidase (ABC) immunohistochemical methods. A total of 44 samples of prostatic tissue were divided into alcohol-fixed (22 cases) and formaldehyde-fixed (22 cases). Each group included 12 non-malignant lesions (hyperplasias and prostatitis) and 10 adenocarcinomas. The best results were achieved with the ABC method in alcohol-fixed tissues, while formaldehyde-fixed tissues gave poor staining despite the use of different enzymes to unmask antigenic determinants. With similar dilutions of the specific antiserum the PaP method gave less intense staining. Cytokeratins were detected in basal and columnar cells, in areas of transitional and squamous metaplasia and in normal transitional epithelium. Columnar cells showed strong staining in the supranuclear portion. Adenocarcinomas gave positive staining for cytokeratins varying from weak to strong. The intensity of staining showed no correlation with the degree of differentiation of the tumor. Different degrees of intensity were frequently observed within the same tumor. High dilutions of the specific antiserum (greater than 1/400) failed to stain carcinomas or stained them poorly, whereas they still stained normal or hyperplastic tissues. Gland-forming tumors showed a highly polarized labelling with the strongest staining in the luminal portion of the cell. The conclusion is that all epithelial prostatic tissues, benign and malignant, express cytokeratins.