However, it is questionable whether histamine release from mast cells is involved in the itching and scratching behavior that is most characteristic of atopic dermatitis, and therefore the cellular mechanisms of the following AD-associated cytokines such as IL-4, IL-13, and IL-31 need to be elucidated, considering that the pathogenesis of AD is promoted by neutrophils, basophils, and CD4+T cells [47,48]. This evidence concerns the gene CD4 and Alzheimer disease.