TNF-α is a 17 kDa cytokine produced by monocytes, macrophages, neutrophils, NK cells, and CD4+T cells. It has a variety of regulatory functions in the immune response and also acts as a potential pyrogen. In response to irritants (infectious agents or tissue damage), TNF-α circulates throughout the body, activates neutrophils, alters the properties of vascular endothelial cells, regulates metabolic activity in other tissues, and exhibits tumor-killing activity by inducing local coagulation. TNF-α plays an important role in the pathogenesis of inflammation in joint tissues and other tissues.