IL2 and hepatitis C virus infection: Thompson and Barkhuizen [45] reported on alterations of IL2, IL2 receptor (IL2R), IL8, and IL1 receptor antagonist (IL1RA) in fibromyalgia and described the mechanism by which alterations in cytokines (in fibromyalgia and hepatitis C) may trigger hyperalgesia and other symptoms mediated by the presence of cytokine receptors on certain cells.