CLASS-I AND CLASS-II MAJOR HISTOCOMPATIBILITY COMPLEX ANTIGEN EXPRESSION ON HEPATOCYTES - A STUDY IN CHILDREN WITH LIVER-DISEASE

Controversy exists regarding major histocompatibility complex antigen expression on hepatocytes. In this study, hepatocyte expression of class I and II major histocompatibility complex antigens was investigated in diseased and normal livers, using indirect immunofluorescent staining of mechanically isolated, viable hepatocytes. Hepatocytes were obtained from 76 children: 10 with autoimmune chronic active hepatitis, nine with primary sclerosing cholangitis, nine with chronic hepatitis B virus infection, five after liver transplantation, 19 with extrahepatic biliary atresia, 11 with α1‐antitrypsin deficiency, four with idiopathic neonatal hepatitis and nine with histologically normal liver. Immunohistochemistry was performed in all cases; flow cytofluorimetry was performed for class I antigens in 38 cases and performed for class II antigens in 18 cases. From three children with autoimmune chronic active hepatitis and two with chronic hepatitis B virus infection, isolated hepatocytes were also incubated with γ‐interferon before staining and analysis. By fluorescence microscopy, class I antigens were detected on hepatocytes from all children, the highest percentage (100%) of positive cells and the most intense staining were observed in untreated patients with autoimmune chronic active hepatitis or primary sclerosing cholangitis and in those with acute rejection of a liver transplant. Reduced class I antigen expression occurred in chronic hepatitis B virus infection. Class II antigens were only detected on hepatocytes from eight patients: three with autoimmune chronic active hepatitis and five with primary sclerosingcholangitis, all untreated. Flow cytofluorimetric analysis confirmed the results obtained by fluorescence microscopy, but it also demonstrated a weak class II antigen expression during liver allograft rejection. After culture with γ‐interferon, the hepatocytes from all five children showed an increase in staining intensity for class I and the acquisition of staining for class II antigens. This study shows that, whereas class I antigens are invariably expressed on liver cells, class II antigens are only found on hepatocytes from untreated patients with immune‐mediated liver disorders in whom class I antigen display is also enhanced. (HEPATOLOGY 1990;12:224–232). Copyright © 1990 American Association for the Study of Liver Diseases