IL31 and Alzheimer disease: The strong activation of adaptive immunity driven by Th2 cells seems to be the dominant mechanism in the acute phase of AD (155), mainly characterized by the secretion of cytokines such as IL-4, IL-5, IL-13 and IL-31, which are involved in the occurrence of keratinocyte apoptosis, inflammation and itching symptoms, to confirm the influence of T cells in the pathogenesis of AD.