The signs of activation of Th2 immune response in schizophrenia include the increase of the IL-4 and IL-10 levels in blood serum, decrease of Th1/Th2 cytokine level ratio (IFN-γ/IL-4, IFN-γ/IL-10, IL-2/IL-4, TNF-α/IL-4) [28]. Here, IL4 is linked to schizophrenia.