Immunohistochemical localization of protein gene product 9.5, ubiquitin, and neuropeptide Y immunoreactivities in epithelial and neuroendocrine cellsfrom normal and hyperplastic human prostate

This study was designed to investigate (a) the presence of protein gene pro duct 9.5 (PGP 9.5), ubiquitin, and neuropeptide Y (NPY) in the neuroendocri ne and secretory epithelium of the human normal prostate and its secretions , and (b) the changes in immunoreactivity to these proteins in men with ben ign prostatic hyperplasia. Western blotting and light microscopic immunohis tochemistry techniques were used and the numerical density of immunoreactiv e neuroendocrine cells, and the volume fractions of immunostained secretory epithelium were evaluated. Western blotting revealed the presence of the t hree antigens in both tissue homogenates and prostate secretion. Some neuro endocrine cells immunoreacted to PGP 9.5 and NPY in all the prostate region s of control specimens. Ubiquitin immunoreactivity was detected in the nucl ei from both basal cells and secretory epithelial cells. The cytoplasm of t he secretory cells and the glandular lumen also showed immunostaining for t he three proteins. The numerical densities of both PGP 9.5 and NPY neuroend ocrine cells were lower in hyperplasia than in controls. No differences in the volume fraction occupied by epithelial immunostaining to both proteins was found between hyperplastic and control prostates. We concluded that (a) PGP 9.5 and NPY, but not ubiquitin, are common antigens in both neuroendoc rine and secretory prostate cells, (b) the three immunoreactive proteins co ntribute to the prostate secretions, and (c) the secretion of ubiquitin is markedly diminished in the hyperplastic epithelium.