Oligoclonal bands in cerebrospinal fluid: a comparative study of isoelectric focusing, agarose gel electrophoresis and IgG index

Objective - To compare the sensitivity and specificity of isoelectric focus ing (IEF) with immunofixation, agarose gel electrophoresis (AGE) and the Ig G index in detecting intrathecally synthesized IgG in multiple sclerosis (M S) and in other nervous system disorders. Materials and methods - Cerebrosp inal fluid (CSF) and serum from 147 patients with various nervous system di seases, 20 of whom had MS, were compared with IEF, AGE and the IgG index. R esults - CSF-restricted oligoclonal bands (OCB) were found in 20 of 20 pati ents with MS using IEF and in 9 of 20 using AGE. OCB were found in 12 patie nts with other nervous system disorders (OND) using IEF and 4 using AGE. Th e mean IgG index was 0.50 in OND and 0.96 in MS (P < 0.0001). Of 20 MS pati ents, 9 had an IgG index above the defined cut-off value of 0.72. Conclusio ns IEF is about twice as sensitive as AGE in detecting OCB in MS. IEF is al so far superior to the IgG index in determining intrathecal IgG synthesis.