Optic neuritis anti-myelin basic protein synthetic peptide specificity

Elevated titers of anti-myelin basic protein (anti-MBP) are highly associated with acute idiopathic unilateral optic neuritis as well as acute relapses of multiple sclerosis (MS). During acute phases of optic neuritis, free/bound antibody ratios are generally above unity, with high titers of free anti-MBP and relatively low or undetectable values of bound antibody. Three to 5 months after the acute phase when the majority of patients have recovered, free/bound anti-MBP ratios are below unity with low titers of free antibody and relatively higher levels of bound anti-MBP. Anti-MBP purified from cerebrospinal fluid of patients with optic neuritis are neutralized by synthetic peptides of human MBP containing overall amino acid residues 61-106 and do not react with synthetic peptides corresponding to residues 1-60 and 107-170. Anti-MBP may either have multiple epitopes in the region corresponding to residues 61-106 or it may react with a discontinuous epitope in this range. The mechanism of the optic nerve demyelination may be associated with anti-MBP binding in situ to MBP in the 61-106 amino acid region.