New Perspective: Bench to Bedside Evidence of the Role of CD8+ T Cells in Alzheimer's Disease.

INTRODUCTION: Amyloid beta plaques and tau tangles are the primary hallmarks of Alzheimer's disease (AD). Recently, passive anti-Aβ immunotherapy for AD has markedly advanced, as supported by evidence from AD animal models and clinical trials. Whereas innate immunity significantly contributes to AD pathology, it does not fully represent the immune mechanisms linked to this condition. Therefore, focus should be directed toward adaptive immunity, encompassing both humoral and cellular immunity. METHODS: Relevant publications and clinical trial data up to February 2026 were systematically reviewed to summarize the mechanisms, therapeutic targets, safety profiles, and translational applications of CD8+ T cells in AD. RESULTS: Clinical and animal studies have particularly suggested a potential involvement of T cells in AD pathogenesis. T cells that infiltrate the central nervous system (CNS) exert both protective and detrimental effects on neural tissue in AD. Because autoreactive CD8+ T cells are generally expected to have cytotoxic effects on CNS cells, they have received less attention. Nevertheless, accumulating evidence suggests that CD8+ Treg cells are involved in various diseases. CONCLUSION: However, the function of anti-Aβ-specific CD8+ T cells in Alzheimer's disease (AD) remains ambiguous. Many subsets of CD8+ T cells have been well-studied in autoimmunity. We suggest that CD8+ T cell subsets identified in AD studies may constitute a promising area for future AD research.