Differentiating patterns of oligoclonal banding in the cerebrospinal fluid improves diagnostic utility for multiple sclerosis

Background: Detection of oligoclonal bands (OCBs) in the cerebrospinal fluid (CSF) is an important adjunct to the diagnosis of multiple sclerosis (MS) and clinically isolated syndromes (CIS). OCBs are considered present if two or more extra IgG bands are present in CSF in comparison to a simultaneously collected serum sample. However, using isoelectric focusing and immunofixation with anti-IgG, we observed two distinct banding patterns, one in which the bands were numerous and prominent (which we termed 'delta') and a much more subtle pattern, with fewer, more indistinct bands ('theta'). Aim: To perform a prospective study to determine the diagnostic implications of the two OCB patterns for multiple sclerosis. Methods: Over a 2-year period, 56 consecutive CSF samples with OCBs were identified. Clinical information and radiological data were collected and correlated with the two banding patterns. Results: Of the 56 positive CSF samples, 46 (82%) demonstrated a delta pattern, and 10 (18%), a theta pattern. The delta pattern was associated with MS/CIS in 34 of 46 (74%) samples, compared with zero of the 10 theta samples (0%, p<0.001). Exclusion of the theta pattern samples increased the positive predictive value of OCB testing from 61% to 74% for MS/CIS. Conclusion: The diagnostic significance of oligoclonal bands in CSF for MS/CIS can be improved by restricting interpretation to the delta banding pattern alone.