Immunopathology of multiple sclerosis.

Multiple sclerosis (MS) is an immune-mediated disease of the CNS that is characterized by inflammation, demyelination, and axon loss. The inflammation in MS appears to be caused by an overactive pro-inflammatory T(H)1 profile in T cells. Demyelination can result as a consequence of direct damage to myelin by inflammatory cells or indirectly because of the environment produced by inflammation. Axon loss occurs in MS lesions starting early in the disease. Treatments now approved by the FDA are most effective in the inflammatory phase of the disease. Because axon loss is irreversible and is responsible for long-term disability, therapies are also needed that enhance remyelination or are neuroprotective.