13,14 Recent studies reported an increase of T cells in AD mouse models15 and in the leptomeninges, CSF, and hippocampus of patients with AD.16 Moreover, T cell infiltration in AD brains is linked with tau pathology, but not with amyloid pathology, and tau aggregation is considered to be an advanced stage of AD progression.17–19 Wei et al. explored the beneficial role of CD8+ T cells in AD mice.20 The involvement of B cells in AD has been reported less extensively than other immune components. Here, MAPT is linked to Alzheimer disease.