Tumor Necrosis Factor Beta (TNF beta) or lymphotoxin-alpha (LT-α) is a 19 kDa tumor necrosis factor family protein with 171 amino acid residues. TNF beta is mainly expressed from lymphocytes, and mediates variety of inflammatory, immunostimulatory, and antiviral responses. TNF beta also involves development in secondary lymphoid organs. It is cytotoxic for different tumor cells in vitro and in vivo.