IL6 and major depressive disorder: Depression is associated with higher levels of IL-1β, IL-6, IFN-γ and TNF-a [154] schizophrenia has been find to exhibit increased concentrations of IFN-γ, IL-2 and IL-6 [153] whereas IL-2, IL-6,IL-8 and IFN-γ were found to be overproduced during BD [152].