Antiviral effects of recombinant tumour necrosis factor in vitro

Tumour necrosis factor (TNF) was first described1as a factor in the serum of mice injected with tubercle bacilli (BCG) and several days later with lipopolysaccharide (LPS). The gene encoding TNF has recently been cloned and pure recombinant human TNF is now available2,3. TNF is known for its in vivoantitumour effect and in vitrocytotoxicity on certain transformed cell lines4,5. Similarities in amino acid sequence and biological activity to lymphotoxin and cachectin have been reported2,6, and very recently a growth-factor-like activity oh diploid fibroblasts was observed7. There is no similarity between these proteins and interferons (IFNs), which are also induced during in vivoinduction of TNF8. Here we describe the antiviral activity of pure recombinant human TNF in a typical in vitroantiviral assay which we discovered while investigating the possible role of TNF as an inducer of IFN.