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IMMUNOLOGY: Letting Killers Through
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Stephen J. Simpson

Multiple sclerosis (MS) is an immune-mediated demyelinating disease
affecting nerves of the central nervous system (CNS). Animal models of MS
have illuminated how helper-type CD4+ T cells could influence the human
form of the disease. Because CD8+ killer T cells are involved in cell-
mediated autoimmunity and can be detected in the lesions of some MS
patients, it is possible that they too might contribute to the pathology
observed in MS.

To test this, Huseby et al. generated CD8+ cytotoxic T cell clones from
mice immunized with a protein component of nerve myelin sheath.
Transferring these cells into normal mice caused loss of coordination,
spastic reflexes, and paralysis. The CNS lesions responsible for these
effects were generally restricted to small blood vessels of the brain and
proximal regions of white matter, a pathology that is distinct from other
forms of CD4-mediated demyelinating disease. This type of perivascular
lesion in the upper CNS suggests that CD8+ T cells might induce distinct
forms of MS or mediate particular stages of the disease. -- SJS

J. Exp. Med. 194, 669 (2001).