Decreased regulatory T cell, increased Th17 and increased CD8+ T cell levels were measured in blood of AD patients (Oberstein et al., 2018; Ciccocioppo et al., 2019; Burgaletto et al., 2020; Gate et al., 2020), while clonally expanded antigen-specific CD8+ T cells were present in cerebrospinal fluid of AD individuals (Gate et al., 2020), indicative of T cell trafficking into the central nervous system. Here, CD8A is linked to Alzheimer disease.