Development of capillary electrophoresis as an alternative to high resolution agarose electrophoresis for the diagnosis of multiple sclerosis.

Abstract

The presence of oligoclonal bands in cerebrospinal fluid (CSF) is used as a diagnostic indicator of multiple sclerosis (MS). These bands, gamma-globulins thought to result from a restricted antibody response directed against autoantigens or viral antigens, are consistent with CSF-specific immunoglobulin synthesis when observed in the spinal fluid and not in the serum. Current methodology commonly involves electrophoresing concentrated CSF with high-resolution agarose gel electrophoresis (HRAGE) followed by protein staining in order to visualize the oligoclonal bands. Capillary zone electrophoresis (CZE) was evaluated as an alternative method. Separation of CSF and serum proteins from 54 patients in a bare silica capillary containing a high pH borate buffer allowed for resolution of the five major zones including the gamma-region and showed a 90% concordance with the results from HRAGE banding studies. Since a simple borate buffer did not provide adequate resolution of the oligoclonal bands in the gamma-region, the separation buffer was augmented with polyethylene glycol (PEG) which provided a significant enhancement in resolution of proteins in this region (24 patient study). In addition to obtaining banding information from electropherograms obtained with these separation conditions, it was feasible to calculate a CSF Index which compared favorably with the results from nephelometry. Finally, we show that zwitterionic additives such as O-phosphorylethanolamine may further enhance resolution and that capallary electrophoresis (CE) may allow oligoclonal banding information to be obtained directly from CSF without concentration.