Keratin immunoreactivity in the benign and neoplastic human prostate.

Keratin immunoreactivity in the benign and neoplastic human prostate was examined immunohistochemically using two monoclonal antibodies with differing specificities. One of these antibodies stained only the basal cells of the normal and hyperplastic prostatic epithelium, with no reactivity in tumor cells of prostatic adenocarcinoma. The other monoclonal antibody recognized a keratin protein present in all normal and hyperplastic columnar (secretory) epithelial cells, as well as in all cancer cells regardless of degree of tumor differentiation. In addition, the second antibody stained acinar and ductal epithelial cells exhibiting premalignant changes. Our findings indicate that keratin immunoreactivity differs among the epithelial cell populations of the human prostate, probably reflecting expression of different keratin proteins. The distinctive patterns of staining obtained with these two antibodies may assist in distinguishing hyperplastic from neoplastic prostatic epithelium, as well as in the recognition of basal cell hyperplasia, transitional cell metaplasia, and premalignant changes.