What is the definition or description of: tumor necrosis factor-alpha?

A cytokine: Tnf Alpha is a protein molecule involved in communication between cells, it is involved in inflammation. The main function is part of the immune system response. It is primarily produced by cells called macrophages but may be produced by many other cells. It causes fever, may induce programmed cell death (apoptosis) and is important in the response to sepsis (via molecules called interleukins).

Immune Cytokine: Tnf-alpha is the prototypic member of a family of protein "hormones" made by the immune system that can cause some cancer cells to kill themselves. It also can cause fever and contributes to weight loss in patients with advanced cancer. It has been tested as a cancer treatment and has not proven to be very effective, but further research is ongoing.