An isoelectric focusing overlay study of the humoral immune response in Theiler's virus demyelinating disease.

Oligoclonal immunoglobulin G (IgG) bands are a frequent feature of inflammatory diseases of the central nervous system (CNS). In multiple sclerosis (MS), cerebrospinal fluid (CSF) oligoclonal IgG bands are a potential clue to the pathogenesis of the disease; however, their particular antigenic target is unknown. We sought to characterize the IgG response in an experimental CNS persistent demyelinating infection by isoelectric focusing (IEF) studies of serum and CSF from mice infected with Theiler's murine encephalomyelitis virus (TMEV). Following IEF, we used a new technique in order to identify TMEV-specific antibodies; focused immunoglobulins were blotted onto nitrocellulose paper which was then overlaid with radiolabeled virus. Autoradiograms showed that most of the TMEV antibody was locally synthesized within the CNS since CSF, but not serum, TMEV antibody had an anodal distribution. CSF IEF TMEV antibody spectrotypes were very similar, presumably because the CSFs were collected from the same inbred mouse strain. CSF TMEV antibody displayed less restricted heterogeneity than the very restricted cathodal CSF oligoclonal IgG bands seen in MS. The new IEF immunoblotting antigen overlay technique will be a powerful detection system to probe for the antigenic target against which MS CSF IgG may be directed.