Myelin Basic Protein (MBP), Cerebrospinal Fluid

This test provides a measure of myelin fragments released into the spinal fluid as a result of the breakdown of myelin during acute phases in the course of demyelinating disease of the CNS (most common example of which is multiple sclerosis). MBP is a 169 amino acid peptide that comprises 30% of the protein of the myelin sheath. While MBP is a useful test in the diagnosis of active MS, some patients with this disorder will have normal limits, especially during remissions, and elevations may be seen in other disorders as well. Therefore, tests such as CSF oligoclonal bands and IgG index, which are positive in 90% of MS patients during active disease or remission, are preferred for the initial diagnosis. However, MBP is useful for providing objective evidence of disease activity.

CSF MBP levels were found to decrease to the level of controls in a group of 11 cases of chronic progressive multiple sclerosis patients receiving immunosuppressive therapy (cyclophosphamide and prednisone). These findings suggest that MBP might be used to monitor the hoped for beneficial effect of such therapy in some cases of MS.

It has been suggested that MBP levels in the CSF might be used in the assessment of radiation-induced myelopathy. MS patients in relapse have been shown to have increased interleukin 1 and interleukin 2 production as the result of MBP stimulated peripheral blood mononuclear cells.