Background: Multiple sclerosis (MS) is an inflammatory disease of the central nervous system with multifocal areas of demyelination. Despite an increased understanding of the mechanisms causing MS, immunological factors that indicate disease activity are only starting to be discovered. Chronic brain inflammation is often associated with an increase in production of IgG in the CSF as determined by the IgG index (normal ≤0.77) and oligoclonal bands (OCBs). Different studies have found variable correlations between these two factors and disease progression. We herein evaluate the correlation of IgG index and OCB with disease progression in Iranian MS patients.

Methods: The IgG index was measured in 54 patients with multiple sclerosis. The progression index (PI), type of disease course and the presence of OCBs were compared in patients with normal, high and very high IgG index.

Results: PI was higher in patients with very high IgG indexes (0.10±0.13) vs. patients with high (0.06±0.05) and normal IgG indexes (0.05±0.07; p>0.05). Secondary progressive (SP) patients had higher IgG indexes than those with relapsing-remitting (RR) courses (2.04±1.24 for SP vs. 1.78±1.45 for RR; p>0.05). The PI was higher in OCB-positive MS patients (0.08±0.10) vs. OCB-negative patients (0.05±0.04) (p>0.05).

Conclusion: Although the findings of this study need to be treated with some caution since this is not a prospective evaluation, the results indicate a trend toward better prognosis of the disease in patients with lower IgG index values. We think that the IgG index is a useful marker of disease activity in MS. Patients with IgG indexes above 1.1 could have an increased risk of progression and they would benefit from early treatment with immunomodulator agents. Our results did not reveal statistically significant prognostic value for IgG index in patients with multiple sclerosis. Thus the results warrant prospective studies to verify the prognostic value of intrathecal IgG synthesis in multiple sclerosis.