INTERLEUKIN-6 (IL-6) - A MOLECULE WITH BOTH BENEFICIAL AND DESTRUCTIVE POTENTIALS

Interleukin-6 (IL-6), a member of the neuropoietic cytokine family, in itially was described in terms of its activities in the immune system and during inflammation. Accumulating evidence supports an essential r ole of IL-6 in the development, differentiation, regeneration and dege neration of neurons in the peripheral and central nervous system. Majo r sites of IL-6 synthesis are neurons and glial cells. Interleukin-6 f unctions are mediated by a specific receptor system composed of a bind ing site and a signal transducer. This receptor system can be modulate d by a complex of IL-6 and soluble IL-6 receptor acting as agonist. Th e IL-6 can exert completely opposite actions on neurons, triggering ei ther neuronal survival after injury or causing neuronal degeneration a nd cell death in disorders such as Alzheimer's disease. Development of selective IL-6 agonists and antagonists, as well as the usage of solu ble IL-6 receptors. offers new possibilities for the treatment of neur odegenerative disorders. Furthermore, optimized genetic mouse models, including transgenic and knockout animals, should help to define the p hysiological and pathophysiological role of IL-6 in the nervous system . (C) 1997 Elsevier Science Ltd.