Lysosomal localization of secretory prostatic acid phosphatase in human hyperplastic prostate epithelium

The ultrastructural localization of secretory prostatic acid phosphatase (PAP) in human benign prostate tissue was accomplished using the immunogold technique on ultrathin Lowicryl sections. Polyclonal antibodies directed against secretory PAP (MW 50 kD) and the lysosomal enzymes alpha-glucosidase and beta-galactosidase as well as an antiserum directed against prostatic antigen (PA) were used. PAP was found in secretory vacuoles of columnar secretory epithelial cells. In addition, double labeling experiments revealed that secretory PAP was also localized in electron-dense organelles of columnar epithelial cells containing alpha-glucosidase and beta-galactosidase. PA was exclusively found in secretory vacuoles of columnar secretory epithelial cells. The results demonstrate the presence of secretory PAP within functional lysosomes and secretory vacuoles of the prostatic columnar epithelial cells and the absence of such PAP-containing lysosomes in the basal cells of the prostatic acini.