IGHE and Alzheimer disease: Patients with severe AD showed a significantly higher frequency of IgE reactivity to allergens such as cat (Fel d 1) and house dust mite (Der p 4 and 10), there were no significant differences in the frequencies of IgE reactivity to the grass pollen allergens Phl p 1, 2, 5 and 6 between the two AD groups, and the IgE reactivity profile of patients with severe AD was more spread toward several different allergen molecules as compared to patients with moderate AD (37).