CXCL8 and myalgic encephalomeyelitis/chronic fatigue syndrome: The median IL-8 concentrations did not differ between patient cohorts but were above the normal reference value (> 150 pg/ml) in 12 of the 16 PCS patients and seven of the 14 ME/CFS patients in the PAT cohort as well as in 17 of the 25 ME/CFS patients and 15 of the 29 PCS patients in the validation cohort.