IGHE and Alzheimer disease: To date, 18 blood/serum biomarkers are known to be associated with disease activity of AD including % eosinophils in blood cell count, lactate dehydrogenase, total IgE, soluble IL-2 receptor, CCL17, CCL18, CCL22, CCL26, CCL27, IL-13, IL-22, IL-24, IL-25, IL-31, IL-33, TSLP, periostin and squamous cell carcinoma antigen-2 [64].