Anti-MAG IgM: differences in antibody tests and correlation with clinical findings

• Published in: Neurological sciences 2020-02, Vol.41 (2), p.365-372
• Main Authors: Matà, Sabrina, Ambrosini, Stefano, Saccomanno, Domenica, Biagioli, Tiziana, Carpo, Marinella, Amantini, Aldo, Giannini, Fabio, Barilaro, Alessandro, Toscani, Lucia, Del Mastio, Monica, Comi, Giacomo Pietro, Sorbi, Sandro
• Format: Article
• Language: English
• Subjects: Adolescent; Animals; Antibodies; Autoantibodies - blood; Child; Child, Preschool; Demyelination; Disease; Enzymes; Female; Glycoproteins; Hospitals; Humans; Immunofluorescence; Immunoglobulin M; Immunoglobulin M - immunology; Laboratories; Male; Medicine; Medicine & Public Health; Myelin; Myelin Sheath - immunology; Myelin-associated glycoprotein; Myelin-Associated Glycoprotein - immunology; Myelin-Associated Glycoprotein - metabolism; Neurology; Neuroradiology; Neurosciences; Neurosurgery; Original Article; Peripheral nerves; Peripheral Nervous System Diseases - drug therapy; Peripheral Nervous System Diseases - immunology; Peripheral neuropathy; Phenotypes; Polyneuropathies - immunology; Polyneuropathy; Psychiatry; Rats; Sulfatide; Variables; Young Adult
• ISSN: 1590-1874; 1590-3478
• DOI: 10.1007/s10072-019-04089-7

Objectives Anti-myelin-associated glycoprotein (MAG) antibody is associated with clinically heterogeneous polyneuropathies. Our purpose was to compare neuropathy phenotypes identified by different anti-MAG tests’ results. Methods Cohort study: Sera from 40 neuropathy anti-MAG EIA positive patients were tested for anti-MAG by Western blot (WB), for anti-peripheral nerve myelin (PNM) on monkey nerve by immunofluorescence assay (IFA), and for anti-HNK1 on rat CNS slices by IFA. Anti-sulfatide antibodies, for comparison, were also tested by EIA. Results Among 40 anti-MAG EIA positive sera, 85% also had anti-PNM IFA reactivity and 67.5% bind HNK1 on rat CNS. Anti-HNK1 positive patients had the classical predominantly distal acquired demyelinating symmetric (DADS) neuropathy with a benign course, while anti-PNM positive but anti-HNK1 negative patients had predominantly axonal neuropathy with a high frequency of anti-sulfatide reactivity and the worst long-term prognosis. Anti-MAG EIA positive patients without anti-PNM or anti-HNK1 IFA reactivity had a CIDP-like polyneuropathy. Conclusion Different methods to test for anti-MAG antibodies identify different clinical and electrophysiological findings, as well as long-term outcome. HNK1 reactivity is the strongest marker of DADS.