Detection of oligoclonal bands in cerebrospinal fluid by immunofixation electrophoresis

Multiple sclerosis is a severe demyelinating disease, the diagnosis of which is aided by biochemical tests, such as detection of oligoclonal immunoglobulin bands in the cerebrospinal fluid (CSF). Because interpretation of agarose gel electrophoresis (AGE) of CSF for oligoclonal bands is often equivocal, we compared immunofixation electrophoresis (IFE) with AGE for 124 consecutive CSF specimens submitted to the Parkland Memorial Hospital Clinical Chemistry Laboratory (Dallas, Tex) for detection of oligoclonal bands. Both methods used the Paragon Electrophoresis Systems (Beckman Instruments, Brea, Calif). Anti-IgG antisera was used exclusively on all specimens. Oligoclonal bands were identified in 23 specimens (18.5%), while the other 101 (81.5%) were interpreted as negative by both methods. Of the positive specimens, 17 (74%) were positive by both methods, 5 (22%) by IFE alone, and 1 (4%) by AGE alone. Of the 23 patients with positive specimens represented, 17 (74%) had been given a diagnosis of multiple sclerosis. The patient whose specimen was positive by AGE alone had a diagnosis of HIV infection with Guillain-Barré syndrome. The sensitivities (with 95% confidence intervals) of IFE and AGE were 73.9% (51.3-88.9) and 56.5% (34.9-76.1), respectively. The specificities of both methods were identical at 95.0% (88.3-98.2). Subjective assessment of the gels demonstrated that the IFE method is consistently easier to interpret than AGE. The IFE method seems to be superior in identifying oligoclonal bands and thus aiding in diagnosis of demyelinating disorders.