Immunologic studies of chronic relapsing EAE in guinea pigs: similarities to multiple sclerosis.

IgG/albumin ratios and presence of oligoclonal bands were studied in neutral pH brain extracts and sera of guinea pigs with chronic relapsing experimental allergic encephalomyelitis (R-EAE). The ratios were found to be significantly increased in central nervous system extracts of animals sacrificed during the first relapse and late stages of the disease relative to those of controls and of animals with acute EAE. These results are consistent with an intracerebral synthesis of IgG found in patients with multiple sclerosis (MS). When the immunofixation (after isoelectric-focusing) patterns of brain extracts and CSF from R-EAE animals were compared with those of controls, R-EAE animals showed distinct oligoclonal IgG bands in the pH region of 7.0 to 9.3, in contrast to diffuse patterns seen in controls. The finding of oligoclonal IgG in brain extracts of these animals further supports the usefulness of R-EAE as an experimental model for MS.