AbstractMultiple sclerosis is a highly complex and heterogeneous disease. At the onset it often presents as a clinically isolated syndrome. Thereafter relapses are followed by periods of remissions, but eventually, most patients develop secondary progressive multiple sclerosis. It is widely accepted that autoantibodies are important to the pathogenesis of multiple sclerosis, but hitherto it has been difficult to identify the target of such autoantibodies. As an alternative strategy, cell-based methods of detecting autoantibodies have been developed. The objective of this study was to explore differences in the binding of antibodies from sera and CSF of multiple sclerosis patients and controls to oligodendroglial and neuronal cell-lines, related to antibody type, immunoglobulin (IgG/IgM), matrix (serum/CSF) and disease course. The oligodendroglial and neuronal cell-lines were expanded in tissue culture flasks and transferred to 96-well plates at a concentration of 50 000 cells/well followed by fixation and blocking with bovine serum albumin. Sera and CSF samples, from healthy controls and multiple sclerosis patients, were incubated with the fixed cells. Epitope binding of immunoglobulins (IgG and IgM) in sera and CSF was detected using biotinylated anti-human IgM and IgG followed by avidin conjugated to horseradish peroxidase. Horseradish peroxidase activity was detected with 3,3′,5,5′-tetramethylbenzidine substrate. Serum from 76 patients and 30 controls as well as CSF from 62 patients and 32 controls were investigated in the study. The binding was similar between clinically isolated syndrome patients and controls, whereas the largest differences were observed between secondary progressive multiple sclerosis patients and controls. Antibodies from multiple sclerosis patients (all disease course combined) bound more to all investigated cell-lines, irrespectively of matrix type, but binding of immunoglobulin G from CSF to human oligodendroglioma cell-line discriminated best between multiple sclerosis patients and controls with a sensitivity of 93% and a specificity of 96%. The cell-based enzyme linked immunosorbent assay (ELISA) was able to discriminate between multiple sclerosis patients and controls with a high degree of accuracy. The disease course was the major determinant for the antibody binding.