Analysis of anti-ganglioside antibodies by a line immunoassay in patients with chronic-inflammatory demyelinating polyneuropathies (CIDP).

Background: Unlike for acute immune-mediated neuropathies (IN), anti-ganglioside autoantibody (aGAAb) testing has been recommended for only a minority of chronic IN yet. Thus, we used a multiplex semi-quantitative line immunoassay (LIA) to search for aGAAb in chronic-inflammatory demyelinating polyneuropathy (CIDP) and its clinical variants. Methods: Anti-GAAb to 11 gangliosides and sulfatide (SF) were investigated by LIA in 61 patients with IN (27 typical CIDP, 12 distal-acquired demyelinating polyneuropathy, 6 multifocal-acquired demyelinating sensory/motor polyneuropathy, 10 sensory CIDP, 1 focal CIDP and 5 multifocal--motoric neuropathy), 40 with other neuromuscular disorders (OND) (15 non-immune polyneuropathies, 25 myasthenia gravis), 29 with multiple sclerosis (MS) and 54 healthy controls (HC). Results: In contrast to IgG, positive anti-GAAB IgM against at least one ganglioside/SF was found in 17/61 (27.9%) IN compared to 2/40 (5%) in OND, 2/29 MS (6.9%) and 4/54 (7.4%) in HC (p = 0.001). There was a statistically higher prevalence of anti-sulfatide (aSF) IgM in IN compared to OND (p = 0.008). Further, aGM1 IgM was more prevalent in IN compared to OND and HC (p = 0.009) as well as GD1b in IN compared to HC (p < 0.04). The prevalence of aGM1 IgM in CIDP was lower compared to in multifocal motor neuropathy (MMN) (12% vs. 60%, p = 0.027). Patients showing aSF, aGM1 and aGM2 IgM were younger compared to aGAAb negatives (p < 0.05). Patients with aSF IgM -positivity presented more frequently typical CIDP and MMN phenotypes (p < 0.05, respectively). Conclusions: The aGAAb LIA revealed an elevated frequency of at least one aGAAb IgM in CIDP/MMN patients. Anti-SF, aGM1 and aGM2 IgM were associated with younger age and anti-SF with IN phenotypes.