Oligoclonal IgM band patterns in multiple sclerosis: A two-center study

Background: Cerebrospinal fluid (CSF) oligoclonal IgM bands (OCMBs) have been suggested as prognostic biomarkers in MS, but serum OCMBs meaning is still uncertain. Objectives: We aimed to assess frequency and clinical relevance of all OCMB patterns. Methods: In this retrospective cohort study, 136 paired sera-CSF from consecutive persons with MS (pwMS) were tested in 2 centers for OCMBs using isoelectric focusing-immunoblotting. Active disease was defined as clinical or radiological relapse occurring during two-year follow-up. Predictors of active disease were analyzed with logistic regressions and Kaplan-Meier survival curves. Results: OCMBs were found in 6.6 % of pwMS as unique-to-CSF (pattern #2), and in 20.6 % as identical in serum-CSF (pattern #4), without between-cohort difference. Active disease was more frequent in those with pattern #2 (88.9 %) and #4 (64.3 %) than in those OCMB-negative (33.3 %, p < 0.001). In multivariate analysis, pattern #2 (OR: 15.9; 95 % CI [1.8-136]), and pattern #4 (OR: 3.3 95 % CI [1.3-8.3]) were independent predictors of active disease. In survival analysis, pattern #2 (p < 0.001) and #4 (p = 0.017) predicted radiological relapses. Conclusions: Our data confirm that CSF OCMB marks poor prognosis in MS. However, both OCMB pattern #4 and pattern #2, with different strength prediction, might be useful to stratify pwMS deserving more aggressive treatments, although the stratification could be achieved in the near future with more standardized and easily measurable biomarkers (e.g., serum neurofilaments).