Autoimmunity in multiple sclerosis.

Multiple sclerosis reportedly coexists with disorders of autoimmune origin. The prevalence with which such disorders occur in the MS population has not been adequately investigated. We reviewed the medical records of 828 patients with definite MS and found that 4.8% had a past or present associated disorder in which autoimmune mechanisms presumably play a role. The cumulative prevalence of these disorders was no higher than that estimated for the general population. Serum from 105 patients, without clinical evidence of an associated autoimmune disorder, was tested for the presence of antinuclear, thyroid, parietal cell, smooth muscle, and mitochondrial antibodies. A significantly higher prevalence (p less than 0.01) of generally low titers of one or more autoantibodies was found in serum from the MS group, compared with a control group of 105 patients with other neurologic disorders. The increased frequency of serum autoantibodies probably reflects the existence of a nonspecific B cell overactivity in MS.