Cytokines are proteins released by the cells in your immune system that help regulate your immune response.
It's possible that people with chronic fatigue syndrome (CFS or ME/CFS) have high levels of cytokines, which, along with several other factors, indicates that their immune system is active even when no virus is present. However, there is conflicting evidence as to whether increased levels of cytokines and other manifestations of immune dysfunction are associated with flares of ME/CFS.
Some experts say treatments aimed at regulating cytokine levels appear promising.
In fibromyalgia, the possible role of cytokines also is under investigation. Some researchers believe acute or reptetitive-stress injuries may lead to long-term activation of pain receptors in the spinal cord, thus resulting in central sensitization.