IL4 and Alzheimer disease: Immunohistochemical and molecular analyses have shown that immune activation of Th2 cells and Th2-derived cytokines (i.e., IL-4, IL-5, IL-13, and IL-31), Th22 cells and Th22-derived cytokines (i.e., IL-22), and Th17 cells and Th17-derived cytokines (i.e., IL-17) is involved in development of acute AD lesions, and progressive activation of Th2 and Th22 cells and their cytokines and significant upregulation of Th1 cells and Th1-derived cytokines (i.e., IFN-γ) are involved in chronic lesions [2,44,45,46,47].