Clinical and Analytical Evaluation of an Enzyme Immunoassay for Myelin Basic Protein in Cerebrospinal Fluid

Abstract Background: RIA of myelin basic protein (MBP) in cerebrospinal fluid (CSF) is commonly used as a biochemical marker of demyelination in patients with multiple sclerosis (MS). Our aim was to develop a sufficiently sensitive ELISA for MBP and evaluate it clinically in patients with MS. Methods: The ELISA used anti-bovine MBP antibody coated on plates and biotinylated anti-MBP antibody. The bound antibody complex was quantified with streptavidin-horseradish peroxidase. MBP was determined in CSF from 84 MS patients and 55 patients with other neurological diseases. Results: The respective within- and between-assay CVs were 4.7% and 7.2% at 200 ng/L, and 6.3% and 8.8% at 2000 ng/L. The detection limit was 30 ng/L. Most of the MS patients with acute exacerbations had markedly increased MBP in the CSF. Longitudinal studies of six MS patients with recurrent exacerbation confirmed this observation. MBP concentrations from 78 MS patients, as tested with our ELISA, correlated well with those obtained by RIA (r = 0.9; P <0.01), but the detection limit of the ELISA was much lower than that of the RIA. Conclusions: This convenient ELISA with higher sensitivity than the existing assays is a suitable routine assay that provides a diagnostic indicator of myelin breakdown in the central nervous system; moreover, it is an excellent indicator of MS disease activity.