Cachectin--Tumour necrosis factor: a cytokine that mediates injury initiated by invasive parasites.

The primary role for which the immune system evolved was a protective one, yet there is no doubt that immune mechanisms can also injure the host. Frequently cited examples of immune-mediated injury include complement-induced disease processes, diseases caused by immune complexes, or those that result from cell-mediated hypersensitivity. During the past few years however, it has become clear that the immune system can also express itself through the action of various cytokines. Gradually, it has been appreciated that these agents may cause disease when produced excessively or inappropriately, and in this article Bruce Beuder and Anthony Cerami discuss one of the most important of these cytokines - cochectin or tumour necrosis factor (TNF).