Epstein-Barr virus-specific intrathecal oligoclonal IgG production in relapsing-remitting multiple sclerosis is limited to a subset of patients and is composed of low-affinity antibodies

Background: The purpose of this study was to investigate intrathecal production and affinity distributions of Epstein-Barr virus (EBV)-specific antibodies in multiple sclerosis (MS) and controls. Methods: Cerebrospinal fluid (CSF) and serum concentrations, quantitative intrathecal synthesis, oligoclonal bands (OCB) patterns and affinity distributions of anti-Epstein Barr virus (EBV) antibodies were evaluated in 100 relapsingremitting MS (RRMS) patients and 200 age- and sex-matched controls with other inflammatory neurological disorders (OIND) and other noninflammatory neurological disorders (NIND). Results: Levels of anti-EBNA-1 and anti-viral capsid antigen (VCA) IgG were different in both the CSF (P < 0.0001 and P < 0.01, respectively) and serum (P < 0.001 and P < 0.05, respectively) among the RRMS, OIND and NIND. An intrathecal synthesis of anti-EBNA-1 IgG and anti-VCA IgG, as indicated by the antibody index, was underrepresented in the RRMS, OIND and NIND (range 1 to 7%). EBV-specific OCB were detected in 24% of the RRMS patients and absent in the controls. High-affinity antibodies were more elevated in the RRMS and in the OIND than in the NIND for CSF anti-EBNA-1 IgG (P < 0.0001) and anti-VCA IgG (P < 0.0001). After treatment with increasing concentrations of sodium thiocyanate, the EBV-specific IgG OCB had low affinity in all 24 RRMS patients analyzed. Conclusions: Our findings do not support the potential role of an EBV persistent brain chronic infection in MS and suggest that an EBV-specific intrathecal oligoclonal IgG production can occur in a subset of MS patients as part of humoral polyreactivity driven by chronic brain inflammation.