Tumor necrosis, << neh KROH sihs, >> factor (TNF) is a protein that performs many functions in the body. Some of its effects are beneficial, but others are harmful. TNF belongs to a large family of proteins known as cytokines . Some cytokines act to increase inflammation, and others serve to decrease or control inflammation. Inflammation is a response by the body to injury or infection (see Inflammation ). TNF acts to increase inflammation. But it also helps moderate and balance the function of other cytokines.
TNF has a wide variety of effects in human beings and other animals. The cells of nearly all tissues in the body have receptors that bind TNF and trigger a reaction in the cell. However, the effect of TNF on a cell depends on the type of cell and tissue stimulated by it. For example, the effect of elevated TNF levels on some brain cells results in decreased appetite and energy levels. In bone and cartilage, it decreases the amount of calcium in the bone and weakens or erodes the cartilage. In bone marrow, TNF acts to decrease the production of red blood cells in some people.
Many diseases are associated with inappropriate or uncontrolled inflammation and increased levels of tumor necrosis factor. These conditions include various forms of arthritis, such skin disorders as psoriasis and atopic dermatitis, multiple sclerosis, and certain types of cancer and hepatitis. In addition, increased levels of tumor necrosis factor have been found in the brain and spinal cord after injury.
However, tumor necrosis factor does not always cause damage in the body. In moderate levels, TNF is an important part of the body’s response to a number of infectious diseases, including malaria and tuberculosis.
Scientists have developed drugs that block the action of TNF on TNF receptors. These drugs are used to treat certain diseases in which increased levels of TNF cause harm, such as various types of arthritis, psoriasis, and Crohn’s disease, a gastrointestinal disease. Scientists are working to develop ways these drugs can be used to treat other diseases. They are also working to develop new drugs. However, researchers continue to study the long-term suppression of TNF and how it affects the body.
