Upregulation of myeloperoxidase in patients with opticospinal multiple sclerosis: positive correlation with disease severity.

To clarify the role of myeloperoxidase (MPO) in multiple sclerosis (MS), we measured serum MPO levels in 86 Japanese patients with relapsing remitting MS, 47 with opticospinal MS (OSMS) and 39 with conventional MS (CMS), and 85 healthy subjects by sandwich enzyme immunoassays and analyzed relationships with clinical features. We found a significant increase in serum MPO in OSMS patients at relapse and remission, and in CMS patients at remission compared with controls. By logistic regression analysis, the clinical variable associated with high level of MPO at remission in OSMS patients (higher than the mean+/-2 S.D. of healthy controls) was only Kurtzke's Expanded Disability Status Scale (EDSS) score in blood sampling (p=0.0245); that is, a greater EDSS scores in the high MPO group, whereas in CMS none were associated. The results of our study suggest that MPO levels in remission are related with severe tissue destruction in OSMS.