Major histocompatibility antigen expression in the liver in acquired immunodeficiency syndrome

Human leukocyte antigen (HLA) class I molecules are normally detected on most nucleated cells, but not on hepatocytes, while the expression of HLA class II antigens is mainly restricted to certain cell types of the immune system. This normal distribution pattern may be altered in human liver in a variety of disorders, particularly in infectious and immune diseases. In view of multiple infections and severe immune alterations in acquired immunodeficiency syndrome (AIDS), we studied the expression of HLA class I and class II antigens in liver obtained at autopsy from ten patients with AIDS and eight control patients, using a panel of monoclonal antibodies and the indirect immunofluorescence method. In spite of viral, bacterial, and fungal infections, HLA class I antigens were detected on hepatocytes in only two patients with AIDS. Human leukocyte antigen class II antigens were found unexpectedly on bile duct epithelium in five of ten patients with AIDS and in one of eight control patients. The aberrant HLA class II antigen expression on bile ducts does not appear to be linked to bile duct damage or infection with cytomegalovirus or other agents, but may be related to immune alterations in patients with AIDS.