Intrathecal IgM species as potential prognostic biomarkers in relapsing-remitting multiple sclerosis

BACKGROUND: Although biomarkers exist for the diagnosis of MS, there is no consensus regarding a prognostic marker, though several forms of intrathecal IgM expression have been suggested, including CSF-restricted bands of oligoclonal IgM (OCMB), and IgM to protein nitrosylation. MATERIALS AND METHODS: The study used a cohort of patients with a diagnosis of relapsing-remitting MS (RRMS), n = 37, studied for up to 17 years. Three biological parameters for IgM were investigated for their prognostic potential. A cohort of patients with diffuse symptoms but no demonstrable neurological disease served as controls (n = 57). RESULTS: Patients with RRMS had signs of inflammation, frequently including an increase in total CSF IgM, the presence of OCMB, as well as an increase in CSF anti-S-nitrosylated protein IgM (α-SNOcys). There was a strong correlation between these IgM species. Patients without both OCMB and α-SNOcys had more benign development of disease, compared to patients with both IgM species at baseline. These latter patients had more aggressive disease development. Whereas the presence of only OCMB indicated worse long-term prognosis, the additional presence of α-SNOcys indicated earlier progression. CONCLUSIONS: This retrospective pilot study suggests that α-SNOcys as well as OCMB are both useful for the prognosis of RRMS, respectively in the shorter and longer term, and might therefore assist the physician in clinical decisions.