Normothermic ischemia induces major histocompatibility complex class I expression in hepatocytes

The hepatic expression of major histocompatibility complex (MHC) antigens is normally limited. However aberrant expression may occur in cholestatic diseases or following liver transplantation. The aim of this work was to investigate the effect of normothermic ischemia on hepatocellular MHC expression. Temporary (90-min) normothermic ischemia of the liver was induced in inbred rats. There was a significant elevation of aspartate aminotransferase and alanine aminotransferase levels after ischemia, rising to their maximum by 6 h. Histologic findings showed large, confluent areas of necrosis, and preserved areas were seen with centrolobular congestion and macrovacuolar steatosis. Expression of MHC class I and II antigens was detected using the immunoperoxidase technique, 1 h, 12 h, 3 days, 7 days and 1 month after the end of intervention. A marked induction of the expression of class I, but not of class II, MHC antigens was observed on the hepatocyte membranes after ischemia. We suggest that normothermic ischemia can occur postoperatively in human liver transplantation and may cause increased expression of class I MHC antigens on hepatocytes, leading to increased sensitivity of liver allografts to rejection by cytotoxic T cells.