IGHE and Alzheimer disease: Regarding the immunopathogenic abnormalities, lymphocytes play a critical role, since T helper 2 (Th2) lymphocyte activation and the cytokines released by them lead to elevated production of immunoglobulin E (IgE) (Figure 1), increased inflammation in the skin, and aggravate the skin barrier defect in AD (Meagher et al., 2002; Klonowska et al., 2018).