A diagnostic index of active demyelination: myelin basic protein in cerebrospinal fluid.

We have developed a radioimmunoassay to measure a specific neurological component, the basic protein of myelin, and have used this test for assessing this component in spinal fluid. The levels of basic protein in spinal fluid correlate closely with the clinical activity of multiple sclerosis; therefore the test can be used for objective evaluation of disease activity in patients with that disorder. Moreover, it is a useful adjunct in the diagnosis of multiple sclerosis and evaluation of potential therapy. In addition, the test is helpful in diagnosing other diseases in which acute breakdown of myelin occurs, especially leukoencephalopathy resulting from irradiation and chemotherapy for treatment of leukemia in children.