Different preparations of IgG anti-IgE purified from patients with AD and rabbit IgG anti-IgE were compared for their triggering effects on the in vitro release of histamine and type 2 cytokines (IL-4, IL-13) from basophils and of histamine and lipid mediators (prostaglandin D2 and cysteinyl leukotriene C4) from human skin and lung mast cells. This evidence concerns the gene IGHE and Alzheimer disease.