NGF and myalgic encephalomeyelitis/chronic fatigue syndrome: In contrast, research on CFS has identified a cytokine signature associated with the severity of CFS: higher circulating levels of CCL11 (Eotaxin-1), CXCL1 (GROα), CXCL10 (IP-10), IFN-γ, IL-4, IL-5, IL-7, IL-12p70, IL-13, IL-17 F, leptin, G-CSF, GM-CSF, LIF, NGF, SCF, and TGF-α have been reported in more severe CFS cases [27].