Myelinotoxic activity on tadpole optic nerve of cerebrospinal fluid from patients with optic neuritis.

The myelinotoxic activity of unconcentrated cerebrospinal fluid (CSF) from eight optic neuritis (ON) and five multiple sclerosis (MS) patients with oligoclonal IgG, and from five ON patients without oligoclonal IgG, was tested in the tadpole optic nerve system. CSF from ON or MS patients with oligoclonal CSF IgG gave a significantly greater number of myelinotoxic lesions than did CSF from ON patients without oligoclonal CSF IgG, CSF from control patients, or physiologic saline. Induction of myelinotoxic lesions may be coupled with the presence of oligoclonal IgG. The findings support the hypothesis that there are two different forms of ON, of which one, characterized by oligoclonal IgG in the CSF, is more closely related to MS.