The small sodium-channel blocking factor in the cerebrospinal fluid of multiple sclerosis patients is probably an oligopeptide

An endogenous factor that is able to reduce the fast transient sodium current of excitable cells has been reported to exist in the cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients. This was confirmed with nine clinically definite MS patients in the acute relapse. In order to purify and chemically identify the factor, microconcentration and gel filtration high-performance liquid chromatography (HPLC) were applied. After each purification step the activity-containing fraction was determined using a biological assay. With all CSFs the activity was contained in the fraction corresponding to 600-800 Da molecular weight, indicating that the factor is chemically homogeneous. The biological activity of the CSF specimens was not correlated to the laboratory CSF data; however, it was correlated to the area under the 210 nm UV light absorption peak in the corresponding chromatogram, i.e. the 600-800 Da MW fraction. As the factor was degradable by acid hydrolysis and a carboxypeptidase, it is suggested that it might be a small peptide. (C) 2000 Elsevier Science B.V. All rights reserved.