Serum IgG antibodies to a 35-kDa P0-related glycoprotein in motor neuron disease.
Using an immunoblot technique we found a significantly higher frequency of serum IgG antibodies to a 35-kDa peripheral nerve myelin glycoprotein in patients with motor neuron disease (MND) (39% of 70) than in patients with neuropathy (13% of 61), other neurological disease (9% of 32) and normal subjects (5% of 20) (P < 0.005 in all cases), but not with multiple sclerosis (MS) (20% of 30) or non-neural immune diseases (25% of 32). Most positive patients had antibody titers of 1:200 or 1:2000 while higher titers were only found in seven patients with MND, one with chronic inflammatory demyelinating neuropathy, two with MS, two with non-neural immune diseases and one with stroke. The reacting protein had a higher molecular mass than P0 and was only faintly bound by an anti-P0 antiserum, but had the same N-terminal amino acid sequence of P0. The difference in molecular mass between P0 and the 35-kDa protein and the IgG reactivity of one patient's IgG with the 35-kDa protein persisted after its deglycosylation and dephosphorylation. Although there is no evidence that these antibodies are pathogenic, their frequent occurrence in MND and other immune-mediated conditions supports the hypothesis of an activation of the immune system in MND.
Nobile-Orazio
E
E
Institute of Clinical Neurology, Centro Dino Ferrari, Ospedale Maggiore Policlinico, University of Milan, Italy.
Manfredini
E
E
Sgarzi
M
M
Spagnol
G
G
Allaria
S
S
Quadroni
M
M
Scarlato
G
G
D000906:Antibodies / Q000032:analysis*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D016472:Motor Neuron Disease / Q000276:immunology*; D009185:Myelin Proteins / Q000276:immunology*; D009422:Nervous System Diseases / Q000276:immunology*
D000906:Antibodies; D007074:Immunoglobulin G; D009185:Myelin Proteins