CD8A and Alzheimer disease: Within the brain, CD8+ T cells can induce phenotypic changes in neurons and microglia [64], and are involved in axonal degeneration and neuronal killing via MHC-I-dependent interactions [65–68], IFN-γ-mediated inhibition of neural stem cell proliferation [69], synaptic elimination by microglia [70, 71] and associate with a decline in synaptic plasticity and cognition in AD pathology [18, 8].