A recent study identified a microglia–T cell communication axis that retains CD8+ T cells in brains with amyloid pathology. Data from this study indicate that CD8+ T cells restrict Alzheimer’s disease pathogenesis.
Gone are the days of considering the brain an immune-privileged site that is isolated from the peripheral immune system. The presence of inflammatory CD8+ T cells within the brain is now known to be associated with a number of neurological disorders, including Alzheimer’s disease1. CD8+ T cells have been described in the brains of individuals with Alzheimer’s disease2 and in mouse models of the disease3; however, whether they contribute to removing proteinaceous aggregates that define the disease or accelerate disease processes is not well understood. Most recent studies support the hypothesis that T cells worsen disease, but new research from Su et al.4 reported in this issue of Nature Immunology instead describes brain-infiltrating CD8+