Tumor necrosis factor induces enzymatic changes in liver comparable to those in extrahepatic cancer.

Human recombinant tumor necrosis factor was administered to rats in small doses to determine whether it causes changes in the activity of liver enzymes similar to those observed in cancer growing extrahepatically. Intraperitoneal injection of increasing doses of tumor necrosis factor (20-100 micrograms/kg/day for 5 days) resulted in a 20-50% decrease in hepatic alanine aminotransferase (P < or = 0.05), a 10-20% decrease in aspartate aminotransferase (P < or = 0.04), and a 50-200% increase in alkaline phosphatase (P < or = 0.02). The activity of hepatic 5'-nucleotidase was unchanged. In the serum, there was no significant change in the activity of any of the enzymes. Histologically, there was no damage detectable by light or electron microscopic examination of the liver, and no evidence of biliary obstruction. However, in frozen liver sections stained histochemically for alkaline phosphatase, there was a dramatic increase in the activity of this enzyme in hepatocytes, which was confined to the bile canaliculi. There was also a 3- to 9-fold increase in the mitotic activity of hepatocytes. Comparable changes have been reported in the tumor-free liver of animals with cancer.