Immunocytochemical localization of a kallikrein-like serine protease (esterase A) in rat salivary glands.

Light and electron microscopic (EM) immunocytochemical methods have been used to localize arginine esterase A, a kinin-generating enzyme immunologically similar to tissue kallikrein, in rat salivary glands. Both polyclonal and monoclonal antibodies to arginine esterase A were used in these studies. By means of a polyclonal antiserum, esterase A was found in granular tubules of submandibular glands and in striated ducts of all three major salivary glands, in a distribution similar to that of tissue kallikrein.

Electron microscopic immunostaining of kallikrein in rat submandibular glands.

The subcellular localization of glandular kallikrein in ducts and tubules of the rat submandibular gland was determined using a postembedding immunostaining (peroxidase--antiperoxidase) technique on thin sections of Eponembedded tissue. Kallikrein was found in large granules of granular convoluted tubule cells and in small, apical granules of striated duct cells. It was also present in patchy aggregates along the surface of striated duct cells and intercalated duct cells, but not in granules of the latter.