Sensitized immunofixation: a new technique for analyzing the oligoclonal pattern of CSF immunoglobulins

Intrathecal immunoglobulin synthesis is observed in more than 90% of all cases of multiple sclerosis, producing a specific CSF IgG oligoclonal electrophoretic pattern. The consensual method used as reference is isoelectric focusing (IEF). We developed a new CSF Ig analysis method by immunofixation (IF). The method includes an immunoenzymatic detection step performed directly on the gel allowing the use of unconcentrated CSF and avoiding the blotting step. The reliability of this method was established by the analysis of 210 CSF/serum pairs including defined, probable and possible MS, other inflammatory CNS diseases and controls (noninflammatory CNS diseases and peripheral nervous system diseases). Intrathecal IgG synthesis was detected in 95.5% of defined MS cases. The specificity for CNS inflammatory diseases including MS diagnosis, evaluated by comparison with controls, was 98.8%. This new method is quicker and visual interpretation is easier than with IEF. It is a semi-automated method that should be considered for standardization of CSF IgG analysis.