For instance, in the case of ME/CFS, symptomatology (assessed by the HADS, COMPASS-31, and PSQI) was positively associated with inflammatory markers such as ET-1, IL-4, IL-6, IL-8, and leptin, whereas this was not the case for long COVID patients. Here, CXCL8 is linked to myalgic encephalomeyelitis/chronic fatigue syndrome.