Pathogenic anti-myelin-associated glycoprotein immunoglobulin M autoantibody (anti-MAG IgM)

Pathogenic anti-MAG IgM autoantibodies are immunoglobulin M class autoantibodies that recognize a highly specific carbohydrate epitope (the HNK-1 glycoepitope) expressed on myelin-associated glycoprotein (MAG) as well as certain peripheral nerve glycolipids (like SGPG)[1][3]. These antibodies are causally implicated in anti-MAG neuropathy, a rare, chronic, demyelinating polyneuropathy characterized by progressive sensory deficits, tremor, and ataxia, predominantly affecting older adults[6]. The pathogenicity of these autoantibodies is due to their direct binding to peripheral myelin and subsequent activation of complement, causing demyelination and impaired nerve conduction[5]. Their levels are a key biomarker for diagnosis and monitoring, though the relationship between titer reduction and clinical improvement is variable[4]. Therapies targeting anti-MAG IgM aim to remove, neutralize, or inhibit their production using B cell-directed agents like rituximab or antigen-specific scavenger molecules[1][2].

Other names

anti-MAG IgManti-MAG autoantibodyanti-myelin-associated glycoprotein IgMAnti-MAG monoclonal IgM paraprotein

B cell depletion (e.g., rituximab targets CD20+ B cells, reducing autoantibody production)[4]. Antibody scavenging/neutralizing: glycopolymers mimic the HNK-1 carbohydrate epitope, binding and sequestering anti-MAG IgM, thereby preventing their pathogenic interaction[2][1].