IL31 and Alzheimer disease: Type 2 cytokines, including IL-4, IL-13, and IL-31; keratinocyte-derived TSLP and IL-33; and type 2 immune cells, including Eos, BS, MC, and Th2 cells, along with elevated serum IgE levels, play critical roles in the pathogenesis of AD and ACD (2, 4, 21, 31, 32).