Purpose of review: In central nervous system (CNS) autoimmune disorders, CD8+ T cells have been reported to exert cytotoxic as well as regulatory functions. In virus-induced (meningo) encephalitis, they are essential for viral clearance, but can also cause severe immunopathology. This review aims to summarize the multifaceted roles CD8+ T cells can play in inflammatory CNS disorders.
Recent findings: Recent evidence for a role of CD8+ T cells in multiple sclerosis comes from genetic association studies confirming a protective effect of the HLA-A0201 allele. Besides their dominance in white matter lesions, CD8+ T cells contribute to immune infiltrates in cortical demyelinating lesions. Having infiltrated the CNS, CD8+ T cells migrate along an inflammation-induced fibrous network. Although CD8+ T cells are generally considered to be crucial for acute viral clearance, they can also induce autoimmune-like immunopathology by, for example, encountering a virus in adulthood while being at the same time latently infected by a related virus. Inadequate control of latent viruses under immunosuppressive treatments or immunodeficiencies is becoming increasingly important in neurology clinical work.
Summary: Future research should aim at identifying the specificity and functional phenotype of brain-infiltrating CD8+ T cells in autoimmune diseases and viral immunopathology in order to develop therapeutic strategies specifically targeting CNS-relevant immune reactions.