Tumor Necrosis Factors: Gene Structure and Biological Activities

Tumor necrosis factor (TNF) is the name given to a serum-derived factor that is cytotoxic for many transformed cell lines in vitro and causes the necrosis of certain tumors in vivo (Carswell et al. 1975). The name lymphotoxin was proposed in 1968 for a factor with similar biological properties that is synthesized by mitogen-stimulated lymphocytes (Granger and Kolb 1968; Ruddle and Waksman 1968). Both of these activities are now known to correspond to distinct proteins. Many other proteins with cytotoxic activities have been described and given a variety of names; however, whether any of these activities can be attributed to cytokines distinct from TNF and lymphotoxin is still not clear. On the basis of structural homology and similarity in biological function, the names TNF-α and TNF-β have been given to TNF and lymphotoxin, respectively. Reviews on the current status of research on TNF-α (Old 1985; Pennica and Goeddel 1986) and...