In our current study, we observed that even though elevated total plasma IgE levels were associated with IgE reactivity to either S. aureus or E. coli, not all AD patients with high IgE showed reactivity to the bacterial extracts (S. aureus IgE‐negative sample with IgE 2800 kU/L; E. coli IgE‐negative sample with IgE 10 600 kU/L), and some patients with relatively low total IgE levels had IgE to bacteria (S. aureus IgE‐positive sample with IgE 38 kU/L; E. coli IgE‐positive sample with IgE 150 kU/L). Here, IGHE is linked to Alzheimer disease.