Antibody to myelin basic protein in extracts of multiple sclerosis brain

Autoimmunity to a neural antigen is a suspected cause of multiple sclerosis (MS), and a candidate autoantigen is myelin basic protein (MBP). Accordingly, saline extracts of brain from patients with MS and other diseases were prepared and the content of immunoglobulin (Ig) determined. Antibody to MBP was measured with a highly-sensitive solid-phase radioimmunoassay using 125I-staphylococcal Protein A. Anti-MBP activity was detected in brain extracts of all eleven MS patients, and in seven out of the eight brain extracts from the patients with other diseases; however the level of anti-MBP activity was significantly higher in the MS extracts (P less than 0.01). Analysis of the MS brain extracts after purification by affinity chromatography columns revealed that the anti-MBP activity was specifically mediated by IgG and resided in the IgG1, IgG2, and/or IgG4 subclasses.