Pascoal et al. (2021) first confirmed the role of activated microglia in the spatial transmission of Tau protein in the brain of patients with AD by positron emission tomography (PET). However, it is not only the central innate immune cells but also the peripheral immune system that are critical for the maintenance of the CNS homeostasis and the progress of AD (Jevtic et al., 2017; Castellani and Schwartz, 2020). This evidence concerns the gene MAPT and Alzheimer disease.