DISTRIBUTION OF INTRAHEPATIC MAST-CELLS IN VARIOUS HEPATOBILIARY DISORDERS - AN IMMUNOHISTOCHEMICAL STUDY

There is evidence that mast cells are involved in a number of pathophy siological processes. The significance of mast cells in hepatic fibros is was examined in 28 patients with histologically normal livers, 34 w ith acute liver diseases, 51 with chronic liver diseases, and 59 with cholestatic biliary diseases, using immunostaining of the mast cell-sp ecific proteinase, tryptase. Mast cells that were positive for tryptas e and for chymase were significantly increased in frequency in fibroti c portal tracts and fibrous septa, particularly in cholestatic/biliary diseases. Mast cells were also increased in frequency around the fibr otic septal and intrahepatic large bile ducts and peribiliary glands o f biliary diseases. However, they were less common or even rare in the sclerotic bile ducts and in scarred portal or septal fibrosis. More t han half of these more numerous mast cells were positive for histamine , and some were also positive for basic fibroblast growth factor. Thes e two substances were detectable by immunoelectron microscopic in the cytoplasmic granules of mast cells. In contrast, mast cell numbers wer e not significantly increased in acute viral or drug-induced hepatitis , or in zones 2 and 3 of the hepatic acinus with respect to pericellul ar and perivenular fibrosis in chronic liver diseases. These findings suggest that mast cells increase in number in cholestatic/biliary dise ases, and to a lesser degree in chronic liver diseases, and are involv ed in the active fibrous enlargement of portal tract and fibrous septa formation and also in the fibrosis of the intrahepatic bile ducts as they display fibrosis-promoting factors such as tryptase, fibroblast g rowth factor and histamine.