TNF alpha, also known as Tumor necrosis factor alpha, is 157 amino acids (soluble form). This protein is produced by neutrophils, CD4+ T cells, macrophage, NK cells, LAK cells, astrocytes endothelial cells, and smooth muscle cells. TNF alpha is cytolytic and plays an important role in immune regulation including hemorrhagic tumor necrosis/cytotoxicity and inflammation, and in regulation of antiviral and immune proliferative and activation responses. Genetic variations in TNF are a cause of susceptibility psoriatic arthritis (PSORAS).