|Molecular model of tumour necrosis factor-alpha (TNF-alpha) molecules (dark blue), bound to monomeric tumor necrosis factor receptors (light blue) in a cell membrane. Binding of TNF-alpha activates the receptor and results in three receptors forming a complex. TNF-alpha is released by white blood cells, mostly macrophages, during inflammatory immune responses, and acts as a signalling molecule. Its release is triggered by injury or bacterial endotoxins. One of its actions is to kill tumour cells, hence its name. TNF-alpha is also involved in a number of inflammatory diseases, including rheumatoid arthritis, psoriasis and Crohn's disease.