Immunohistochemical demonstration of pancreatic α-amylase and trypsin in intrahepatic bile ducts and peribiliary glands

Abstract

Epithelia of intrahepatic bile ducts and peribiliary glands were immunohistochemically examined for pancreatic alpha-amylase and trypsin in 54 normal autopsied livers. alpha-Amylase was evaluated with a polyclonal antibody, and trypsin was assayed with both polyclonal and monoclonal antibodies. alpha-Amylase was observed in large ducts, septal ducts and peribiliary glands in most livers and was seen in interlobular ducts in seven (13%) livers. Trypsin immunoreactivity with the polyclonal antibody was observed in peribiliary glands in 21 (39%) livers; it was absent in intrahepatic bile ducts in all but one liver. Trypsin immunoreactivity with the monoclonal antibody was present in large ducts, septal ducts and peribiliary glands in about 70% of the livers and was seen in interlobular ducts in two (4%) livers. Bile ductules were always negative for the two antigens. Some epithelia of peribiliary glands positive for both alpha-amylase and trypsin histologically resembled pancreatic acinar cells. alpha-Amylase and trypsin immunoreactivities of intrahepatic biliary epithelia and pancreatic aninar cells were eliminated by absorption of primary antibodies by alpha-amylase or trypsin, suggesting the specificities of the immunoreactivities. These data suggest that epithelia of intrahepatic large ducts, septal ducts and peribiliary glands contain pancreatic alpha-amylase in most livers and that they contain trypsin in about 70% of livers. alpha-Amylase and trypsin may be secreted into intrahepatic bile duct lumens, thereby exerting important effects on the physiology of the intrahepatic biliary tree and hepatic bile.