Contribution of CD8 T lymphocytes to the immuno-pathogenesis of multiple sclerosis and its animal models

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) characterized by multi-focal demyelination, axonal loss, and immune cell infiltration. Numerous immune mediators are detected within MS lesions, including CD4+ and CD8+ T lymphocytes suggesting that they participate in the related pathogenesis. Although CD4+ T lymphocytes are traditionally considered the main actors in MS immunopathology, multiple lines of evidence suggest that CD8+ T lymphocytes are also implicated in the pathogenesis. In this review, we outline the recent literature pertaining to the potential roles of CD8+ T lymphocytes both in MS and its animal models. The CD8+ T lymphocytes detected in MS lesions demonstrate characteristics of activated and clonally expanded cells supporting the notion that these cells actively contribute to the observed injury. Moreover, several experimental in vivo models mediated by CD8+ T lymphocytes recapitulate important features of the human disease. Whether the CD8+ T cells can induce or aggravate tissue destruction in the CNS needs to be fully explored. Strengthening our understanding of the pathogenic potential of CD8+ T cells in MS should provide promising new avenues for the treatment of this disabling inflammatory disease.