Furthermore, although the number of infiltrating eosinophils, CD4+ T cells and mast cells in the skin was not significantly affected by the topical application of 17-AAG, circulating eosinophil percentages, serum levels of histamine, and eosinophil peroxidase (EPX) activity in the skin were significantly reduced in 17-AAG-treated AD mice compared to vehicle-treated AD mice. This evidence concerns the gene CD4 and Alzheimer disease.