Oligoclonal IgG in rabbits with experimental allergic encephalomyelitis: Non-reactivity of the bands with sensitizing neural antigens

Oligoclonal IgG bands have recently been reported to occur in cerebrospinal fluid (CSF) and serum of rabbits with experimental allergic encephalomyelitis (EAE). To examine the specificity of these bands, a) individual bands eluted from rabbit CSF and sera were tested by radioimmunoassay (RIA) for anti-MBP activity and b) rabbit sera were absorbed with the neuroantigens used for sensitization. RIA of eluates from sequential agar gel slices of the entire IgG region of serum or CSF from MBP sensitized rabbits showed that anti-MBP activity occurred throughout the IgG region and did not localize to specific band-containing fractions. Furthermore, there was no change in banding patterns following absorption of EAE rabbit sera with washed brain homogenates, soluble MBP or MBP conjugated to Sepharose beads. Therefore, our results indicate that the oligoclonal IgG response in EAE is not preferentially directed against the sensitizing neuroantigen, and we raise the possibility of nonspecific B cell activation.