Interleukin-31 (IL-31) is a cytokine of the IL-6 family mainly produced by CD4+ Th2 cells3 It binds to the IL-31R complex, which is composed of IL-31 receptor α (IL-31RA) and oncostatin M receptor β (OSMRβ), mediating the induction of pruritus and the release of numerous proinflammatory mediators such as IL-4, IlL-6, IL-8, IL-13, IL-16, and IL-324 High serum levels of IL-31 have been demonstrated in both intrinsic and extrinsic AD, and these levels seem to correlate with disease activity.5 Here, CD4 is linked to Alzheimer disease.