An Immunohistochemical Study on the Distribution of Endotoxin

ABSTRACT

This study was performed to investigate the distribution of endotoxin in various organs after intraperitoneal injection of E. coli homogenator(0111:B4, 3X10(9)cells/200g of body weight). Sprague-Dawley rats were intraperitoneally injected with E. coli homogenator and sacrificed 1 and 3 hours after injection. The lung, liver, and kidney were immunohistochemically stained with avidin-biotin complex method and observed by light and electron microscopy. On the light microscopy, granular deposits of reaction products of immunohistochemical stain were found on the cytoplasmic membrane of endothelial cells and some of parenchymal cells of all organs observed. Electron microscopic study revealed finely granular reaction products on the surface of endothelial cells and some of parenchymal cells. The pinocytotic vesicles of endothelial cells demonstrated reaction products in the early phase of experiment. The distribution of reaction products were prominent in the liver among three organs. The Kupffer cells showed the most sensitive and strongest positive reaction. The hepatocytes and endothelial cells revealed weak positive reaction 3 hours later. The alveolar macrophages of the lung were also positive from the early phase of endotoxemia, while the pneumocytes and alveolar septa demonstrated weakly positive reaction in the later phase. The capillary endothelium of the kidney revealed positive reaction from the early phase. According to above results, it is concluded that the endotoxin entered into the systemic circulation was captured in the liver and lung. And both mononuclear phagocytic system and endothelial cells could be activated or damaged by endotoxin.