Depression was associated with abnormal levels of peripheral cytokines and chemokines compared to HCs. IL-6, TNF-a, IL-10, sIL-2R, CCL-2, IL-13, IL-18, IL-12, and sTNFR2 were significantly elevated, IFN-gamma was slightly reduced. Eighty-two case-control studies (50). This evidence concerns the gene IL18 and major depressive disorder.