These cells play a critical role by producing antiviral cytokines and removing virus-infected cells.124 CD8+ T cells can also produce inflammatory cytokines such as TNF, which then activate microglia and other immune cells.125 Recent studies have found an increased number of CD8+ T cells present in patients with Alzheimer’s disease, which result in an increase in neuroinflammation.126,127 Although, other studies found no significant difference in CD8+ T cell frequencies compared with healthy controls.59 These inconsistencies may exist due to differences in the stage of disease studied. This evidence concerns the gene CD8A and Alzheimer disease.