Electron microscopy of liver lesions in primary biliary cirrhosis. II. A bile duct with chronic non-suppurative destructive cholangitis.

An 80 micrometers bile duct with typical features of chronic non-suppurative destructive cholangitis was examined by electron microscopy. Many inflammatory cells, including lymphocytes, macrophages and plasma cells infiltrated among epithelial cells of the bile duct. Epithelial cells were compressed and deformed by infiltrating lymphocytes. These lymphocytes were in contact with epithelial cells at small points or large areas. The intercellular distance was about 10 or 20 nm at the contact areas. The mode of contact and intercellular distance coincided with the results of in vitro experiments on lymphocyte cytotoxicity against target cells. Some epithelial cells in contact with lymphocytes showed degenerative changes. Necrotic changes were observed in bile duct epithelial cells undergoing emperipolesis. The invading lymphocyte in the epithelial cell had osmiophilic substances on the surface. These sites of emperipolesis seem to be the areas of lymphocyte cytotoxicity against epithelial cells.