An extensive search for autoantibodies to myelin basic protein in cerebrospinal fluid of non-multiple-sclerosis patients: implications for the pathogenesis of multiple sclerosis.

Inflammation of multiple sclerosis (MS) brain and spinal cord tissue consists of macrophages, T lymphocytes and cytokines as well as B lymphocytes and immunoglobulins (IgGs). IgG can be detected in high concentrations in both central nervous system tissue and cerebrospinal fluid (CSF). Using a sensitive radioimmunoassay (RIA), autoantibodies to myelin basic protein (anti-MBP) can be detected in the CSF of 90-95% of MS patients with active disease. The purpose of the present report was to determine whether these same autoantibodies can be reliably detected in non-MS patients. Between 1978 and 1998, CSF was collected from 1,968 control non-MS patients with psychiatric, inflammatory and noninflammatory neurological diseases as well as nonneurological systemic diseases, and anti-MBP were measured by the same RIA used to detect anti-MBP in MS CSF. Anti-MBP were undetectable in 98% of CSF samples from non-MS controls. In the remaining 2% of control samples, CSF IgGs capable of binding to MBP in vitro were unpredictably detected. This latter group included 1% of patients with miscellaneous diseases such as encephalomyelitis, 5 siblings with familial spastic paraparesis, rare patients with strokes, Wernicke-Korsakoff's syndrome, inherited leukodystrophy, motor neuron disease and some patients with miscellaneous spinal cord diseases. An additional 1% of patients included a group with neurological symptoms suggestive of early or predisseminated MS. The high prevalence of free and/or bound anti-MBP in the CSF of MS patients and the rare and unpredictable occurrence in the CSF of non-MS patients suggest that autoimmunity to MBP may be operative in the demyelination of MS. Molecular clones of anti-MBP with specificity towards variable surface or cryptic MBP epitopes in vivo may determine whether or not they are involved in the demyelinating process, and this variability may also be present within the MS population. Potential mechanisms of anti-MBP-mediated demyelination in MS patients are discussed.