Cytokine networks: do we understand them well enough to facilitate clinical benefits?

Cytokines are chiefly local transmitters. The cloning of these molecules has been driven by the belief that they will be of major therapeutic benefit, despite the problems inherent in their clinical administration systemically, a non-physiological route. This brief review discusses the clinical use of cytokines and the possibilities for clinical benefit of interfering with cytokine function. A major step forward in the past few years has been the realization that shed extracellular domains of cytokine receptors are the most common natural cytokine inhibitors, described for TNF, IFN gamma, IL-2, IL-4, IL-7, for example. These natural cytokine inhibitors may offer interesting therapeutic possibilities, as they are enhancing or "replacing" the natural anti-cytokine mechanisms.