Several studies reported AD-associated changes in peripheral immune cell compositions in AD patients, such as increase of memory CD4 T cells and activated CD8 and CD4 T cells, and a parallel decrease of CD4 naïve T cells, compared to healthy control subjects (Larbi et al., 2009; Pellicanò et al., 2012; Lueg et al., 2015). Here, CD4 is linked to Alzheimer disease.