Intrathecal synthesis of autoantibodies to myelin basic protein in multiple sclerosis.

A solid phase radioimmunoassay was used to detect anti-myelin basic protein (MBP) antibodies in the CSF and serum of multiple sclerosis (MS) patients and controls. CSF and serum samples were assayed prior to acid hydrolysis in order to detect free anti-MBP as well as after acid hydrolysis to measure the total (free and bound) amount of antibody. An anti-MBP index controlling for serum levels as well as the degree of breakdown of the blood brain barrier was used to estimate intrathecal synthesis of anti-MBP. MS patients with acute exacerbations or chronically progressive disease have significantly elevated levels of both free and total CSF anti-MBP. The anti-MBP index is also significantly increased in MS patients with both forms of active disease. Anti-MBP antibodies are intrathecally produced in MS patients with active disease.