Tumor necrosis factor (
TNF,
tumor necrosis factor alpha,
TNFa,
cachexin, or
cachectin) is a cell signaling protein (
cytokine) involved in systemic
inflammation and is one of the cytokines that make up the
acute phase reaction. It is produced chiefly by activated
macrophages, although it can be produced by many other cell types such as
CD4+ lymphocytes,
NK cells,
neutrophils,
mast cells,
eosinophils, and
neurons.