Chronic immune activation in the eosinophilia-myalgia syndrome

Eosinophilia-myalgia syndrome (EMS) is a multisystem illness of uncertain pathogenesis that occurred in an epidemic related to the ingestion of contaminated L-tryptophan. To investigate the role of immune dysfunction in EMS we prospectively measured a serologic index of T-cell activation, the soluble interleukin-2 receptor (sIL-2R), in 7 patients followed into the late stages of the illness. As a group, EMS patients had significantly elevated sIL-2R levels throughout the study. Five patients suffered chronic symptoms of myalgia, arthralgia, muscle cramps, fatigue, or subjective memory impairment and all had persistently elevated sIL-2R levels. Two patients had near-resolution of EMS and normal sIL-2R levels. We conclude that chronic symptoms are common in EMS and are associated with persistent T-cell activation as measured by serum sIL-2R levels. These findings suggest that immunosuppressive treatment may be beneficial in EMS.