Chronic Fatigue: Immune System Abnormalities

Some, although not all, studies have reported that a majority of CFS patients have allergies to food, pollen, metals (such as nickel or mercury), or other substances. (Most allergic people, in any case, do not have CFS.) Some research indicates that people with both allergies and emotional disorders, such as anxiety or depression, may be more vulnerable to the effects of the inflammatory response. This is a harmful overreaction of the immune response, which triggers the release of a number of immune factors, that can cause fatigue, joint aches, and fever, which can also affect the hypothalamus-pituitary-adrenal system in the brain.

One theory that may help tie in some of the various factors common to CFS suggests that allergies, stress, and infections may deplete a chemical in the body called adenosine triphosphate (ATP). This chemical stores energy in cells and studies have reported a deficiency in many CFS patients. Supporting this theory was a study in which patients reported reduced CFS symptoms after they took a coenzyme called NADH, which increases ATP levels.

The risk profile for chronic fatigue syndrome is similar to the risk profiles for a number of autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome, and multiple sclerosis. These disorders also have early symptoms resembling CFS. Common to such diseases are the presence of high levels of autoantibodies, antibodies that attack the patient's own cells. Some studies are finding high levels of autoantibodies directed against substances in cell nuclei in CFS patients. Others, however, have found no evidence of an autoimmune factor.

In one study, some patients, particularly those with severe CFS symptoms, had higher-than-normal numbers of infection-fighting white blood cells known as CD8 killer T cells, which launch attacks on invading viruses and other disease-causing microorganisms. These same people had lower-than-normal levels of another white blood cell known as the suppressor T cell, which helps to shut down the immune response once the invading organisms have been killed. In such cases, the immune system becomes persistently overactive and produces fatigue, muscle aches, and other symptoms of CFS.

Other studies have indicated lower amounts of so-called natural killer cells, (which comprise a major component of the innate immune system) in many CFS patients, which might make them more susceptible to viruses.