title: Frequency and clinical correlates of anti-neural IgM antibodies in neuropathy associated with IgM monoclonal gammopathy.
abstract: We studied the frequency and clinical correlates of different IgM specificities in 75 patients with neuropathy associated with IgM monoclonal gammopathy. Patients were tested for IgM reactivity with the myelin-associated glycoprotein, P0, neurofilaments, and tubulin by immunoblot; with GM1, asialo-GM1, GM2, GD1a, GD1b, sulfatide, and chondroitin sulfate C by enzyme-linked immunosorbent assay; and with brain and nerve glycolipids by overlay high-performance thin-layer chromatography. Forty-two patients (56%) had high titers of IgM antibodies to MAG; 4 (5%), to sulfatide (1 also to myelin-associated glycoprotein); 4 (5%), to the 200-kd neurofilament (2 also to myelin-associated protein); and 1 each, to GD1b and chondroitin sulfate C. No reactivity was found in 26 patients (35%). More patients with anti-myelin-associated glycoprotein IgM (62%) than with unknown IgM reactivity (31%) had a predominantly sensory neuropathy (p < 0.025). Nerve conduction findings were consistent with a demyelinating neuropathy in 77% of patients reactive to myelin-associated glycoprotein and 24% with unknown reactivity (p < 0.0001) and the mean conduction velocity of peroneal nerve was lower in the former group (22.9 m/sec) than in the latter group (39.6 m/sec) (p < 0.000001). Patients with anti-sulfatide IgM had a sensorimotor neuropathy with morphological evidence of demyelination while anti-neurofilament IgM was not associated with homogeneous findings. Patients with anti-GD1b or anti-chondroitin sulfate C IgM had a predominantly motor impairment. The frequent occurrence of anti-neural IgM antibodies in neuropathy associated with IgM gammopathy, and their frequent, though not constant association with similar neuropathy features, support their possible pathogenetic role in the neuropathy.
authors.affiliation: Institute of Clinical Neurology, Centro Dino Ferrari, Ospedale Maggiore-Policlinico, University of Milan, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Nobile-Orazio
authors.forename: E
authors.initials: E
authors.lastname: Manfredini
authors.forename: M
authors.initials: M
authors.lastname: Carpo
authors.forename: N
authors.initials: N
authors.lastname: Meucci
authors.forename: S
authors.initials: S
authors.lastname: Monaco
authors.forename: S
authors.initials: S
authors.lastname: Ferrari
authors.forename: B
authors.initials: B
authors.lastname: Bonetti
authors.forename: G
authors.initials: G
authors.lastname: Cavaletti
authors.forename: F
authors.initials: F
authors.lastname: Gemignani
authors.forename: L
authors.initials: L
authors.lastname: Durelli
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000209:etiology / Q000276:immunology*; D010265:Paraproteinemias / Q000150:complications / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D007075:Immunoglobulin M