In AD, T cells are hyperdifferentiated into T helper 2 (Th2) cells, and the mRNA expression levels of the Th2 cytokines such as interleukin (IL)-4, IL-5, IL-13, and interferon-γ (IFN-γ) are significantly increased when they are compared to those in normal skin [3]. Here, IL4 is linked to Alzheimer disease.