Interleukins are a family of proteins that regulate the maturation, diff- entiation, or activation of cells involved in immunity and inflammation, and belong to a broader family termed cytokines. Collectively these proteins are the key orchestrators of host defense and the response to tissue injury. There are currently 23 different interleukins (numbered from IL-1 to IL-23), although the full extent of the interleukin family will only become clear upon analysis of the human genome sequence. Most important, interleukins are central to the pathogenesis of a wide range of diseases that involve...