The pathogenesis of biliary atresia in Japan: immunohistochemical study of HBV-associated antigen.

An immunohistochemical study of HBV-associated antigen in the liver of 16 Japanese infants with biliary atresia revealed positive findings in 13 of the cases for HBc and/or HBs antigens. The positive cells were mainly small liver cells distributed in the peripheral zone of the lobule, and a few lymphocytes were observed in contact with or around the positive liver cells for HBV-associated antigen. Again, HBc antigen was demonstrated almost exclusively in the cytoplasm of positive liver cells. As these findings suggest the possibility of destruction and drop-out of cells constituting the interlobular bile duct in the junctional area by an immunological mechanism, the probability of HBV infection being an important factor in causing and accelerating biliary atresia cannot be denied. Positive findings for HBV-associated antigen similar to those found in biliary atresia are also seen in neonatal hepatitis and choledochal cysts. These conditions are therefore presumed to belong to the same category.