IGHE and Alzheimer disease: Among two other relatively clear phenotypes, intrinsic AD (normal IgE level) shows significantly elevated expression of IL-17, IL-23, IL-22 cytokines associated with S100As, elafin/PI3, CCL20 expression by keratinocytes (thus resembling psoriasis), whereas extrinsic AD (high IgE level) shows similar expression levels of Th2 cytokines (29).