IL13 and major depressive disorder: In comparison to healthy controls, MDD patients have higher levels of IL-6, tumor necrosis factor (TNF)-, IL-10, soluble IL-2 receptor, IL-13, C-C chemokine ligand-2, IL-13, IL-18, IL-12, IL-1 receptor antagonist, and soluble TNF receptor 2 in their peripheral blood (17).