Interestingly, studies showed that AD is a biphasic inflammatory allergic skin disease that can predominantly secrete the Th2 cytokine like IL-4, which plays a pivotal role in acute phase in AD and responsible for B cell class switching to IgE production, whereas in the chronic phase in AD, Th1 cells secrete IL-2, IL-12, and IFN- γ, all of which plays a crucial role in the resolution of allergic-related immunopathology. This evidence concerns the gene IL2 and Alzheimer disease.