The existence of HLA-DR antigens was investigated in biliary atresia, using monoclonal anti-HLA-DR antibody.In 4 of the 5 patients with BA, biliary epithelial cells of the frozen liver biopsy specimen taken at the time of Kasai operation showed positive for anti-HLA-DR antibody. Because of the availability of anti-HLA-DR antibody that can be used for the formalin-fixed spacimen, 15 liver biopsy specimen previously taken from 9 patients with BA were investigated for the positivity. In 11 of the 15 specimens, HLA-DR antigen was positive, while 4 was negative. All of these negative 4 were the specimen taken at reoperations performed at after 130 days old. As there are recent reports on increased expression of HLA-DR antigen of epithelium in the patients with various immunopathologial conditions such as primary biliary cirrhosis, rejected liver graft, and graft-versus-host disease. This increased expression of HLA-DR antigens in BA suggests that the pathogenesis of BA be an immunological assalt.
