Analysis of sequential changes in major histocompatibility complex expression in human liver grafts after transplantation.

The expression of class I and class II major histocompatibility complex (MHC) antigens in human liver grafts was analyzed in 88 liver biopsies from 22 patients. For the staining of MHC antigens, a panel of monoclonal antibodies directed against monomorphic determinants of class I and class II molecules and an indirect immunoperoxidase method were used. In the reference biopsies, class I antigens were expressed on all cell types but only weakly on hepatocytes; class II was only expressed on Kupffer cells, interstitial cells, and endothelia. After transplantation, this pattern of MHC expression was markedly modified. Increased class I expression on hepatocytes and HLA-DR expression on bile ducts occurred in the absence of clinical rejection. During acute rejection, class I was strongly expressed and HLA-DR weakly expressed on hepatocytes; on bile ducts, HLA-DR expression was further increased. Cytomegalovirus hepatitis caused class I and HLA-DR induction on hepatocytes; strong induction of HLA-DR on bile ducts was also found in cholangitis. These findings have a number of implications for the pathophysiology of rejection of the transplanted liver.