Components in multiple sclerosis cerebrospinal fluid that are detected by radioimmunoassay for myelin basic protein

Components in cerebrospinal fluid that are antigenically related to myelin basic protein have been identified by a technique described recently [Barbarese, E., Braun, P. E. & Carson, J. H. (1977) Proc. Natl. Acad. Sci. USA 74, 3360-3364] involving separating the cerebrospinal fluid proteins by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and measuring the individual components by radioimmunoassay for myelin basic protein. Samples of cerebrospinal fluid from 48 different patients (23 with definite multiple sclerosis, 4 with suspected multiple sclerosis, and 21 with other neurological diseases) were examined by this technique. The results indicate that cerebrospinal fluid can contain at least three separate components that are detected by radioimmunoassay for myelin basic protein. On the basis of their apparent molecular weights, the three components were identified as follows: component I, intact myelin basic protein; component II, proteolytic fragments of myelin basic protein; and component III, a protein of unknown origin with an apparent molecular weight of 50,000. Most samples of cerebrospinal fluid (45 of 48) from patients with multiple sclerosis and from patients with other neurological diseases contained components I and II. Component III was detected in all of the samples from patients with definite multiple sclerosis, in three of four samples from patients with suspected multiple sclerosis, and in none of the samples from patients with other neurological diseases. Some implications of these findings are discussed.