Evidence of local synthesis of smooth-muscle antibodies in the central nervous system in isolated cases of multiple sclerosis and chronic lymphocytic meningoencephalitis.

Paired samples of serum and concentrated cerebrospinal fluid (CSF) from 53 patients with multiple sclerosis (MS) and from 36 patients with other neurological diseases were adjusted to an equal concentration of IgG and examined for occurrence of auto-antibodies. Anti-nuclear antibodies, anti-mitochondrial antibodies, and rheumatoid factor were not detected with increased frequency in the materials studied. Smooth-muscle antibody (SMA) was, however, detected in CSF and serum from three patients with MS and one patient with chronic lymphocytic meningoencephalitis, and in the CSF only from one additional patient with MS. The SMA activities of the CSF were 4 to 16 times higher than in the matching sera, suggesting a local SMA synthesis within the central nervous system. The SMA was associated with electrophoretically restricted fractions of IgG, but an association between SMA and oligoclonal IgG of the CSF could not be demonstrated in the SMA-positive patients by the methods used.