CXCL8 and rheumatoid arthritis: Two studies [173,174] demonstrated IL-8 levels in the CSF of FM patients that were higher than those of HC and rheumatoid arthritis patients; in addition, in FM patients, IL-8 levels in CSF were higher than in peripheral blood samples, leading the authors to conclude that the first source of this chemokine is the CNS—in particular, astrocytes and microglial cells.