In MDD and suicide-related behavior, inflammatory cytokines such as interleukin (IL)-1, IL-6, IL-17, tumor necrosis factor-α (TNF-α), and IL-4 trigger the secretion of various anti-inflammatory cytokines, including IL-10, IL-13, and transforming growth factor-β (TGF-β) [13]. The gene discussed is IL4; the disease is major depressive disorder.