Mast cells are known to be present in human liver but their distribution and density in normal livers and in chronic liver diseases have not previously been examined. In this study, we quantified mast cell numbers and examined their distribution in percutaneous biopsy specimens from normal livers (n = 8) and in two chronic progressive liver diseases: primary biliary cirrhosis (PBC) (n = 40) and alcoholic liver disease (n = 33). We compared differences in mast cell density between these two forms of chronic liver disease because it had been suggested that mast cells may play a role in the development of liver fibrosis, particularly in patients with chronic cholestatic liver disease who frequently have increased plasma histamine levels. Mast cells were identified by immunohistochemistry using a specific monoclonal antibody (AA1) raised against mast cell tryptase after an initial study showed this to be more sensitive for the detection of mast cells than the conventional histochemical stain, toluidine blue. Our results showed that small numbers of mast cells (3.9 ± 3.3/mm2) are present within the portal tracts and sinusoids of normal livers. In progressive chronic liver disease, increased numbers of mast cells were present, which correlated with the increasing amounts of liver fibrosis present. We found significantly more mast cells in the PBC group compared with the alcoholic group for a given amount of fibrosis. Our findings suggest that mast cells and their mediators may play a role in liver fibrogenesis. (HEPATOLOGY 1995; 22:1175–1181.).

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Vascular endothelial cells are antigenically heterogeneous and therefore it has been recommended that a range of immunohistochemical markers is employed to show the presence of cells of endothelial origin in surgical pathology. In this study we applied three monoclonal antibodies--to factor VIII-related antigen, JC70 (CD31), QBend 10 (CD34)--and Ulex europaeus agglutinin type 1 lectin (UEA-1), to six consecutive cases of left atrial myxoma. We found that JC70 and QBend 10 consistently stained myxoma cells in all their different growth patterns contrasting with factor VIII-related antigen expression and UEA-1 binding which were restricted to areas which showed morphological evidence of vascular differentiation. These findings suggest that the constituent cells of atrial myxomas show more widespread endothelial differentiation than has previously been recognized and that differences in immunohistochemical staining may reflect the maturation status of these cells.

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