Assessment of the reproducibility of oligoclonal IgM band detection for its application in daily clinical practice.

BACKGROUND: The presence of oligoclonal IgM bands (OCMB) in cerebrospinal fluid (CSF) is an unfavourable prognostic marker in multiple sclerosis. There is no commercial test to investigate OCMB status. However, a sensitive and specific isoelectrofocusing (IEF) and western blot method was described. We aimed to study the inter-centre reproducibility of this technique, a necessary condition for a reliable test to be incorporated into clinical practice. METHODS: The presence of OCMB was analysed by IEF and western blot with prior reduction of pentameric IgM. We assayed the reproducibility of this test in a blinded multicentre study performed in 13 university hospitals. Paired-CSF and serum samples from 52 neurological patients were assayed at every centre. RESULTS: Global analysis rendered a concordance of 89.8% with a kappa value of 0.71. CONCLUSION: These data indicate that OCMB detection by means of IEF and western blot with IgM reduction shows a good interlaboratory reproducibility and thus can be used in daily clinical setting.

Response to interferon in multiple sclerosis is related to lipid-specific oligoclonal IgM bands.

The objective of this study was to investigate whether the presence of lipid-specific oligoclonal IgM bands (LS-OCMB) in cerebrospinal fluid (CSF) influences the response to treatment with beta-interferon in relapsing-remitting multiple sclerosis (RRMS) patients. We performed a collaborative prospective study including RRMS patients with brain MRI and LS-OCMB studies performed before starting interferon treatment. The primary endpoint was the risk of having a relapse after treatment initiation. Secondary endpoints included relapse rate, relapse-rate reduction, proportion of relapse-free patients and proportion of patients with sustained disability increase during follow-up. One-hundred and two patients were included. After a mean follow-up of 37.4 months, the risk of suffering a relapse was two-fold higher in patients with LS-OCMB (hazard ratio 2.0, 95% confidence interval 1.1-3.8). LS-OCMB+ patients showed lower reduction in relapse rate (51.8% versus 80.8%; p < 0.0001), higher relapse rate in the first year (0.8 versus 0.2; p = 0.001), lower proportion of relapse-free patients (25% versus 61.3%; p = 0.003), and higher proportion of patients with sustained 1.0 increase in the Expanded Disability Status Score (45% versus 12.9%; p = 0.0003). In conclusion, LS-OCMB can have an influence on the response to interferon treatment in RRMS patients. They could be used as a biological marker to predict high inflammatory activity after treatment.

The risk of relapse after a clinically isolated syndrome is related to the pattern of oligoclonal bands.

We prospectively assessed the risk of second relapse in 192 patients with clinically isolated syndromes (CIS) divided into three groups: patients lacking oligoclonal IgG bands (OC-IgG, 25.7%), those showing OC-IgG (52.4%), and those with both OC-IgG and lipid-specific IgM bands (LS-OC-IgM, 22%). OC-IgG increased 9.3-fold the risk compared to lacking OC-IgG; OC-IgG+LS-OC-IgM increased the risk 39.6-fold compared to not having OC-IgG and 4.4-fold compared to having only OC-IgG. Median time to second relapse was 0.7 years for patients with OC-IgG+LS-OC-IgM and 3.3 years for those with only OC-IgG. Therefore, CSF analysis identifies CIS patients at risk of second relapse.