1　TNF ligand and receptor superfamily membersTumor Necrosis Factor (TNF) supergene family and its cognate family of rel ated r eceptors (TNF-R) have expanded in the past few years to include at least 17 lig ands and 22 receptors (The New TNF Nomenclature Scheme, http://www.gene.ucl.ac.uk/users/nomenclature/genefamily/tnfinfo.html)[1]. With the exception of LTα,whichlacks a hydro phobic transmembrane region, allof the ligands are type Ⅱintegral membrane pro teins that may also function as soluble proteins. Many of the TNF superfamily ligands pair with a single, although some specific receptor, including TNFα, LT α, TRAIL, FasL, LIGHT and TRANCE/RANKL, bind to multiple receptors (Tab 1).