Tnf-α effect on oxygen free radical scavenging and generating enzymes in rat liver

The presence of cancer induces metabolic alterations in distant, tumor-free tissues and organs of the host. A remote humoral effect of cancer growing extrahepatically is an increase in the activity of oxidant and a decrease of antioxidant enzymes in the liver of the tumor-bearing animal. We speculated that TNF-α, produced by host cells, the cancer, or both, is responsible for these changes. When human recombinant TNF-α, 100 μg/kg/d i.p. for 5 days, was injected in groups of rats fed ad libitum, starved, or pair-fed, a decrease in the activity of superoxide dismutase and glutathione peroxidase and an increase in xanthine oxidase was observed, particularly with pair-fed controls. It is concluded that TNF-α, directly or indirectly, causes these enzyme alterations in the tumor-free liver of a tumor-bearing host.