[Intrathecal immunity in multiple sclerosis: comparison of quantitative and qualitative methods of analysis].

The diagnosis of multiple sclerosis (MS) is difficult in the early cases, and the demonstration of oligoclonal IgG bands in cerebrospinal fluid (CSF) is the most frequent and undisputed laboratory abnormality observed. Intrathecal synthesis of immunoglobulins can be proved by three methods: quantitatively by the IgG index, and qualitatively by demonstration of oligoclonal bands in the CSF (electrophoresis and electrofocusing method). Electrofocusing method is a new technique to research oligoclonal IgG bands and has a higher resolution than electrophoresis. In 81 patients with clinically definite MS, 96.2% of CSF were abnormal with electrofocusing method instead of 60.4% of electrophoresis and 83.9% of IgG index. In our cases, electrofocusing was the best method to prove an immunoglobulin intrathecal synthesis in MS.