CD4 and Alzheimer disease: Accordingly, there is: (i) a greater degree of clonal expansion of CD8+ T cells in the CSF of AD patients compared to healthy controls,78 (ii) an increased clonal expansion of CD4+ T cells in CSF of AD patients relative to control individuals95 and (iii) tau-mediated clonal T cell expansion in the brain parenchyma in the TE4 mouse model84 have all been reported.