IGHE and Alzheimer disease: In addition, Simpson et al. demonstrated that AD patients that had been colonized with S. aureus had higher levels of type-2 biomarkers (higher blood eosinophil counts and serum levels of total IgE, CCL17, and periostin) and exhibited greater allergen sensitization than both non-colonized AD patients and non-atopic, non-colonized control individuals [46].