IGHE and Alzheimer disease: Effector/memory Tregs express high levels of ICOS, which contributes to the survival and expansion of Tregs.36 Moreover, ICOS+ Tregs, which likely derive from expansion of thymus‐derived Tregs, are potentially highly suppressive.37 We found that the percentages of ICOS+ Tregs are increased in the blood of AD patients, regardless of FLG mutation status, serum IgE level and EASI score (Figure 4A).