High interleukin levels ((IL)-1β, IL-2, IL-6, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, the soluble IL-6 receptor (IL-6R), and the IL-1 receptor antagonist (IL-1RA)) and dysregulation of the hypothalamic-pituitary-adrenocortical (HPA) have been identified in patients with depressive disorders. Here, TNF is linked to depressive disorder.