IL4 and myalgic encephalomeyelitis/chronic fatigue syndrome: Horning et al. reported that patients with chronic myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) exhibit an exhausted immune system, as evidenced by significant decreases in IL-1b, IL-1ra, IL-4, IL-10, IL-12, IL-17, and increases in chemokine (C-C motif) ligand 2 (CCL2) and the major monocyte chemoattractant [83].