Comparison of agar gel electrophoresis and isoelectric focusing in multiple sclerosis and subacute sclerosing panencephalitis.

Isoelectric focusing (IEF) and agar gel electrophoresis (AGE) were used to examine cerebrospinal fluid (CSF) and sera from patients with multiple sclerosis (MS) and subacute sclerosing panencephalitis (SSPE). All 15 SSPE samples and 29 of the 33 MS CSF samples showed oligoclonal IgG bands by AGE and IEF. Serum bands were more frequent in SSPE than in MS and were more commonly detected by IEF than by AGE. In MS CSF the number of bands on IEF correlated with: (1) disease duration, (2) CSF IgG, (3) CSF IgG/albumin ratio, and (4) central nervous system IgG synthesis. Serial studies revealed increases in IEF band number in 4 of 10 MS and 3 of 5 SSPE CSF specimens; fluctuations in band intensity were also noted. Densitometric scans of CSF IEF gels showed high, sharply angled IgG band peaks in SSPE; the CSF band peaks in MS were flatter and had higher background IgG. The SSPE pattern could be made to resemble the MS pattern through addition of normal polyclonal IgG to SSPE CSF. These findings suggest that in addition to oligoclonal IgG, polyclonal IgG is synthesized locally within the central nervous system in MS.