Anti-GD2-like IgM autoreactivity in multiple sclerosis patients

Seric IgM autoreactivity in 100 multiple sclerosis (MS) and 106 control (70 of whom had other neurological diseases) patients was assessed either by immunohistochemistry on normal human CNS tissue or to GD2, GD1a, GD3 by ELISA and thin layer chromatography (TLC) techniques. By double immunohistochemistry, we found that 44% of the total MS population showed seric IgM reactivity to oligodendrocytes and myelin, this finding being particularly frequent in patients with secondary progressive MS. In the non-MS cohort, positive signals were seen only in one patient. In all cases, extraction of lipids from CNS sections abolished the immunoreactivity. Among the gangliosides investigated by ELISA, anti-GD2-like IgM autoantibodies were detected in the serum of 30% of MS patients, a subgroup of whom (below 10%) reacted also with GD1a and/or GD3. More than 85% of MS cases with anti-GD2-like IgM immunoreactivity by ELISA showed also IgM antioligodendrocyte/myelin staining by immunohistochemistry. However, no immunostaining in MS sera was observed when gangliosides were resolved by TLC. A positive correlation with neurological disability was observed, as the Expanded Disability Status Scale of MS patients with anti-GD2-like IgM autoreactivity by ELISA was significantly worse than seronegative MS cases. The results of the present study enforce the role of glycolipids as potential autoantigens and of IgM autoantibodies in MS pathogenesis.