In people with chronic pain that has no obvious cause, chemical messengers that rev up or slow down inflammation are often out of balance, a new study finds. These proteins, called cytokines, are made predominantly by immune cells.
Millions of people have chronic pain without any known injury or disease, a condition sometimes called fibromyalgia syndrome. Diagnostic tests are unreliable and treatments are often unsatisfactory, says Claudia Sommer, a neurologist at the University of Würzburg in Germany. To assess whether cytokines influence such chronic pain, she and her colleagues identified 40 people who had endured unexplained chronic pain for an average of 14 years. Most had symptoms that fit the description of fibromyalgia.
The scientists compared blood samples from these patients with samples from 40 people without pain who matched them in age and gender. All the people—with or without chronic pain—had similar complements of three inflammation-caus