CD4 and Alzheimer disease: The skin lesions present in AD are frequently colonized with S. aureus strains that produce SsAgs [23, 43] and recent evidence has indicated that one type of skin-homing T cell (CD4 +/Foxp3 +) in AD patients exerts effector TH2-like functions promoting SsAg stimulation, which may aggravate allergic skin inflammation [25].