Relationship between interleukin 1 (IL1), tumor necrosis factor (TNF) and a neutrophil attracting peptide (NAP-1)

Although IL 1 and TNF are biochemically distinct and bind to different cell membrane receptors, they each exhibit only a few distinct biological properties, and have a great number of activities in common. Thus, IL 1 and TNF are radioprotective, have cytocidal effects for some tumor cells, remodel bone and cartilage, induce fever, inflammation, fibroplasia, and angiogenesis. The overlapping effects of IL 1 and TNF are in part due to the induction of the same spectrum of cytokines and their receptors. Both IL 1 and TNF induce IL 2-receptors, IL 6, colony stimulating factors and acute phase proteins which may contribute to their immunoenhancing, inflammatory and radioprotective effects. IL 1 and TNF frequently also are coordinately released by cells and have cooperative effects. For example, IL 1 together with TNF has synergistic in vivo radioprotective effects and in vitro terminal differentiative effects on tumor cell lines. Overall, these data point to the existence of common as well as distinct post-receptor signal transduction pathways for IL 1 and TNF. IL 1 and TNF each can induce a number of cell types to produce IL 6, which appears to act as another "broad spectrum" cytokine. In addition, both IL 1 and TNF induce NAP-1 production by human monocytes and fibroblasts. This novel cytokine which has been purified, sequenced, cloned, expressed and synthesized, may account for some of the in vivo acute inflammatory effects of these cytokines.