Storage of alpha‐1‐antitrypsin in intrahepatic bile duct cells in alpha‐1‐antitrypsin deficiency (Pi Z phenotype)

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Abstract
Storage of .alpha.-1-antitrypsin (AAT) was found in a small number of bile duct cells in liver tissue specimens from patients with Pi MZ, Pi SZ and Pi ZZ phenotypes. The storage appeared in the form of intracellular AAT immunoreactive inclusions. On EM investigation, AAT-like material was detected within cisternae of the RER [rough endoplasmic reticulum] and SER [smooth endoplasmic reticulum]. Such AAT inclusions were found in proliferating bile ductules in conditions such as cirrhosis, focal nodular hyperplasia and extrahepatic obstruction. They were also observed in normal biliary structures at the level of the canals of Hering, bile ductules and interlobular ducts in 13 out of 47 cases. Apparently, the intrahepatic bile duct cells are a further source of AAT and in case of defective export of AAT from the cell, as is the case for the Z protein, the protein accumulates not only in hepatocytes but in biliary cells as well.