ABSTRACT
Tumor necrosis factor (TNF) was originally described as a factor present in the serum of induced mice and capable of causing hemorrhagic necrosis in methylcholanthrene-induced sarcomas in Balb/c mice. The genes for both human TNF and murine TNF were cloned independently by several research groups. TNF is produced mainly by macrophages activated by bacterial products, viruses, parasites, and probably other stimuli. The receptors can be found in human serum and urine, and can inhibit TNF effects on target cells. The cellular effects of TNF eventually lead to activation, differentiation, or death of the target cells. The effects of TNF on the liver are seldom direct, but are nevertheless worthwhile discussing. TNF is a cytokine that has an important role in inflammatory reactions and in the response against infection. The relationship between TNF and the liver is bidirectional, since the liver can also produce substances that protect against the lethal activities of TNF.
