LYSOSOMAL CYSTEINE PROTEINASES IN RAT EPIDIDYMIS

To examine the precise localization of lysosomal cysteine proteinases, cathepsins B, H, and L in rat epididymal epithelial cells, immunohist ochemistry and enzyme assay were applied to the epididymal tissue. Gra nular immunodeposits for cathepsins B and H were detected in epididyma l epithelial cells, whereas faint or no immunoreactivity for cathepsin L was found. Moreover, immunoreactivity for cathepsin B appeared main ly in principal cells and was more intense in the head of the epididym is than in the tail, whereas that for cathepsin H appeared in both pri ncipal and dear cells and was more intense in the tail than the head. By enzyme assay, activities of cathepsins B and H showed a similar dis tribution to that of the immunoreactivity. The cathepsin L-specific ac tivity was distributed evenly in each part of the epididymis and was a lso detected in epididymal fluids obtained from the body and tail part s. By immunoblotting, proforms of cathepsins B, H, and L were present in the seminal fluid. The results suggest that cathepsins B and H are involved in the intracellular degradation system of epididymal epithel ial cells, and proforms of cathepsins B, H, and L may be secreted into the epididymal duct lumen.