Comparison between agarose gel electrophoresis and isoelectric focusing of CSF for demonstration of oligoclonal immunoglobulin bands in neurological disorders.

Isoelectric focusing and agarose gel electrophoresis of CSF and serum revealed similar frequencies of oligoclonal bands in multiple sclerosis (100% with both methods), infectious CNS disorders (38 and 23%) and other neurological diseases (8 and 10%). In selected cases with unsure CSF oligoclonal bands on agarose gel electrophoresis, isoelectric focusing displayed definite oligoclonal bands. In contrast to agarose gel electrophoresis, isoelectric focusing revealed evidence for oligoclonal bands in serum as well as in CSF in 41% of the multiple sclerosis patients, indicating diffusion from CSF to serum. In 4 cases with gammaglobulin bands appearing in both CSF and serum on agarose gel electrophoresis, isoelectric focusing revealed normal CSF and serum protein patterns at pH above 6.4 where most IgG is migrating.