Apoptosis, or programmed cell death, occurs during normal cellular differentiation and development of multicellular organisms. Apoptosis is induced by certain cytokines including TNF and Fas ligand of the TNF family through their death domain containing receptors, TNFR1 and Fas. A novel cell death receptor was recently identified by several groups independently and designated DR3, Wsl-1, Apo-3, TRAMP and LARD1-5. The ligand for this novel cell death receptor has not yet been defined. DR3 is highly expressed in the tissues enriched in lymphocytes including PBL, thymus and spleen. Like TNFR1, DR3 induces apoptosis and NF-κB activation.