Cerebrospinal fluid oligoclonal bands in the diagnosis of multiple sclerosis. Isoelectric focusing with IgG immunoblotting compared with high-resolution agarose gel electrophoresis and cerebrospinal fluid IgG index.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. We compared the diagnostic performance of isoelectric focusing (IEF) combined with IgG immunoblotting to high-resolution agarose gel electrophoresis for the detection of intrathecal synthesis of IgG due to the MS disease process. In 20 patients with definite MS, IEF and high-resolution agarose gel electrophoresis had sensitivities of 90% and 60%, respectively. In the 51 patients with no evidence of MS, the methods had specificities of 94% and 96%, respectively. With a prevalence of 15% in this test population, IEF and high-resolution agarose gel electrophoresis had positive predictive values of 73% and 73% and negative predictive values of 98% and 93%, respectively. The IEF method improves the sensitivity and the negative predictive value of the oligoclonal-banding assay, the IEF gels are easier to interpret, and the IEF assay requires a smaller cerebrospinal fluid volume.