IL4 and Alzheimer disease: To investigate the expression of the functional cytokines of CD4+ T cells, plasma IFN-γ, IL-4, IL-9, IL-17, IL-22, and Treg levels were measured by ELISA, and higher IFN-γ, IL-9, IL-17, and IL-22 levels and decreased IL-4 and IL-35 concentrations were observed in the AD group than in the NAD group (Figures 3(a) and 3(b)); this trend was consistent with the observed CD4+ T cell levels.