Immunohistological detection of Saruplase (recombinant single-chain urokinase-type plasminogen activator) in normal rat tissue.

Saruplase--a recombinant single-chain urokinase-type plasminogen activator was identified immunohistochemically in normal rat tissue after intravenous administration by means of a polyclonal antibody. For this purpose, rat tissues were fixed in various ways (liquid nitrogen, ethanol, formaldehyd solution). Saruplase could be detected by the PAP method, streptavidinbiotin system and indirect immunofluorescence in the kidney (proximal tubule), liver (hepatocytes, Kupffer cells) and spleen (reticular cells). Saruplase was not localized in the rat endothelium. It is discussed that the rat-specific receptors for urokinase-type plasminogen activator on endothelial cells cannot bind Saruplase due to the extreme species specificity.