By Ulrike Kaunzner, MD
Synopsis: This retrospective study found that while oligoclonal bands (OCB) remain a highly sensitive and specific marker for multiple sclerosis (MS), they have limited diagnostic utility for other autoimmune central nervous system disorders. The findings underscore that OCB testing should be reserved for suspected MS and interpreted cautiously outside the MS context.
Source: Leech J, Sauer BM, Baduashvili A, et al. Diagnostic accuracy of oligoclonal bands for CNS autoimmune disorders in acutely ill adults. Neurol Clin Pract. 2025;15(5):e200510.
Oligoclonal bands (OCBs) indicate intrathecal immunoglobulin G (IgG) synthesis, typically produced by clonally expanded B cells and plasma cells in the central nervous system (CNS) and are detected in cerebrospinal fluid (CSF) by isoelectric focusing and immunoblotting. They reflect a localized humoral immune response.
Although OCB testing is central to diagnosing multiple sclerosis (MS), its diagnostic utility in undifferentiated neurologic illness remains uncertain. OCBs are not specific to MS. They can appear in other inflammatory, infectious, and autoimmune CNS disorders, including neurosyphilis, neuroborreliosis, subacute sclerosing panencephalitis, autoimmune encephalitis, neurosarcoidosis, and Sjӧgren syndrome. In these non-MS autoimmune conditions, OCBs are detected in only a minority of cases (typically 10% to 25%, as per prior publications) and are less sensitive and specific than in MS. The diagnostic value of OCBs depends heavily on clinical context and magnetic resonance imaging (MRI) and serum findings, since a positive or negative result alone is insufficient to confirm or exclude autoimmune pathology.
Several factors contribute to the broad use of OCB testing beyond MS. High sensitivity in MS may create an overestimation of its value in other autoimmune diseases, and the increasing identification of novel autoantibodies has led clinicians to use OCBs as a nonspecific marker of CNS autoimmunity. However, this practice may risk misdiagnosis, delays in appropriate therapy, and unnecessary interventions.
A retrospective, single-system study analyzed all patients undergoing OCB testing from January 2018 to December 2020 in inpatient and emergency settings, capturing acute, undifferentiated presentations. Among 926 patients, 78 were diagnosed with MS and 148 were diagnosed with other autoimmune CNS disorders. For MS, OCBs demonstrated high diagnostic performance (sensitivity 92%, specificity 89%). In contrast, sensitivity and positive predictive value for non-MS autoimmune CNS disorders were poor (28% and 45%, respectively). Notably, 62% of non-MS autoimmune patients had zero OCBs. Positive OCBs also were found across a wide range of non-autoimmune and vascular conditions, including peripheral nervous system diseases, limiting their discriminatory power outside demyelinating disease.
OCB testing remains invaluable for confirming MS but offers limited utility for other CNS autoimmune or inflammatory disorders. Results must be interpreted in the broader clinical context, incorporating MRI findings, disease history, and specific antibody panels (e.g., myelin oligodendrocyte glycoprotein [MOG], aquaporin-4 [AQP4], or glial fibrillary acidic protein [GFAP]). Key points include that absent OCBs do not exclude autoimmune disease, low-level OCB positivity (one to four bands) is nonspecific, and high OCB counts (five or more bands) modestly increase the likelihood of autoimmunity but warrant further targeted testing rather than stand-alone conclusions. Routine OCB testing in nonspecific neurologic presentations is not recommended. The test should remain a focused diagnostic tool rather than a reflexive screening measure.
Commentary
Although OCBs are pivotal for MS diagnosis, their extension to non-demyelinating conditions offers limited benefit and may complicate clinical decision-making. Limitations of this study include its retrospective design, single-center scope, and lack of quantitative CSF measures, such as IgG index or kappa free light chains. Future research should explore whether advanced immunologic profiling or integration with next-generation antibody assays could improve the detection of true autoimmune activity and clarify the diagnostic role of OCBs across neuroimmunologic and, particularly, CNS neuroinflammatory diseases. Clinicians are encouraged to align OCB testing practices with evidence-based guidelines, ensuring judicious and context-driven use.
Ulrike W. Kaunzner, MD, is Assistant Professor of Clinical Neurology, Weill Cornell Medical College.
