Tumor necrosis factor alpha (TNF-alpha) got its name from its ability to kill off tumor cells in mice. It’s a protein that’s released from a wide range of cells in order to activate the immune system.

It accomplishes this in a variety of ways, including (but not limited to) inducing fever, helping initiate the “acute phase response,” which increases inflammation in response to injury and can help fight off microbes and clean up, as well as attracting white blood cells to sites of injury and infection. Since it “moves cells” to do its job and because it promotes inflammation, it is known as a “proinflammatory cytokine.” In short, TNF-alpha boosts the immune system.

While “boosting the immune system” may sound like a good thing, the immune system is pretty powerful and can cause a lot of collateral damage in the body if boosted too much. For instance, some of the effects^[1] of malaria infection are not due to the parasite itself, but because of overproduction of TNF-alpha. It may also cause some trouble in other major diseases, including inflammatory bowel disease^[2], Alzheimer’s^[3], and depression^[4]. Lower levels may be associated with longevity as well, but the research on this has been conflicting^[5].