Preferential synthesis of the G1m(1) allotype of IgG1 in the central nervous system of multiple sclerosis patients.

Quantitations of the G1m(1) and G1m(3) allotypic determinants of human immunoglobulin G were performed by radioimmunoassay on cerebrospinal fluid and serum samples from patients with multiple sclerosis and from patients with other neurological disorders. In multiple sclerosis patients that were heterozygous for these determinants, G1m(1) concentration in the cerebrospinal fluid was greatly increased-reflected by an increased ratio of G1m(1)-in comparison with that of patients with other neurological disorders. These results suggest that in the heterozygous multiple sclerosis patients, most of the plasma cells in the central nervous system that secrete oligoclonal immunoglobulin G preferentially synthesize G1m(1) IgG1 molecules.