Mast cell subpopulations in chronic inflammatory hepatobiliary diseases

Aim/Background: In various hepatobiliary diseases mast cells have been found to be associated with fibrogenesis. However, mast cell subpopulations have not been investigated in the human liver in normal subjects or in disease. Human mast cells are categorized into mast cells positive for tryptase (MCT) only and mast cells positive for both tryptase and chymase (MCTC). Methods: In this study we investigated mast cell subpopulations (MCT and MCTC) by double immunostaining for mast cell tryptase and chymase as well as by a computer-aided quantitative morphometry in 13 normal livers and in 193 liver tissue specimens comprising of primary biliary cirrhosis (n=43), autoimmune hepatitis (n=11), chronic hepatitis B (n=37), chronic hepatitis C (n=41), alcoholic liver disease (n=40) and hepatolithiasis (n=21). Results: The densities of MCT and MCTC per 1 mm(2) stroma were low in normal livers but high in chronic liver diseases, and correlated positively with the degree of fibrosis. The percentages of MCT and MCTC subpopulations were 25% and 75%, respectively. The percentage was almost the same in normal livers and various hepatobliliary diseases, as well as between less fibrotic cases and more fibrotic cases in liver diseases. Conclusions. These results suggest that MCT and MCTC subpopulations in healthy and diseased livers do not change during liver fibrosis of any etiology.