Radioimmunoassay of myelin basic protein in spinal fluid. An index of active demyelination.

With a sensitive radioimmunoassay that can measure as little as 2 ng of basic protein in cerebrospinal fluid we studied 303 patients with a variety of neurologic diseases. Patients with active demyelinating diseases had high levels (17 to 100 ng per milliliter) of basic protein. Moreover, patients with multiple sclerosis in acute exacerbation had these high levels, those with slowly progressive multiple sclerosis had lower levels (6 to 16 ng per milliliter), and those in remission had less than 4 ng per milliliter, comparable to the control population. Thus, the assay appears to be a useful index of active demyelination.