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 α 1 –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).