TNF-β, also called lymphotoxin-α (LT-α), is expressed by a variety of cells, including T cells, B cells and natural killer (NK) cells. It can be secreted and, like TNF-α, binds with high affinity to TNF receptors 1 and 2 (TNFR-1 and TNFR-2), and it is transiently expressed on the cell surfaces of activated B and T cells, where it forms a complex with LT-β as an LTα1β2 heterotrimer. TNF-β can activate many kinds of immune cells, and prompt secretion of other cytokines for infection clearance. For some physiological processes, TNF and LTαβ work together as components of an integrated signaling network that is defined in part by communal sharing of receptors and ligands.