With regards to levels of IL-2, IL-8, IL-17 A and TNF-α (the cytokines that were regulated by IFN-α but did not distinguish between PF and RF), for IL-2 there were no significant differences between groups (p =  0.14), while for the others there were significant differences between the groups (p values ranging <0.001 - 0.003, see Table 2), and differences were all similar to those described for IL-6 and IL-10, i.e., higher in both PF and RF groups compared with CFS and controls, but not different between PF and RF or between CFS and controls. Here, CXCL8 is linked to myalgic encephalomeyelitis/chronic fatigue syndrome.