Isoelectric focusing of cerebrospinal fluid proteins in the diagnosis of multiple sclerosis.

Isoelectric focusing was adapted for analysis of cerebrospinal fluid (CSF) proteins with commercially available materials. CSF from cases of multiple sclerosis or chronic neurologic infections showed abnormal populations of IgG, verified by immunofixation, particularly in the high-alkaline regions (high-alkaline bands). Agarose electrophoresis showed a similar number of abnormal specimens, but patterns were more clearly defined by isoelectric focusing. Despite increased sensitivity, isoelectric focusing is too complex to replace agarose electrophoresis, but it may be useful in clinically difficult cases when agarose electrophoresis patterns are questionable.