Myelin Associated Glycoprotein Antibodies (MAG)

Myelin associated glycoprotein (MAG) is found in central and peripheral nervous system myelin. MAG appears on oligodendrocytes and Schwann cells. The localisation of MAG in the peripheral region in myelin suggests that MAG may participate in neuron-glial cell interaction that leads to myelination. This hypothesis is supported by the observation that MAG antibodies may lead to demyelination. MAG antibodies are believed to be pathogenic [1]. IgM autoantibodies against MAG are found in sensory motor neuropathies and IgM paraprotein associated neuropathies. The determination of MAG antibodies helps to separate IgM associated neuropathies from other commonly acquired polyneuropathies (e.g. chronic inflammatory demyelinating polyneuropathy). Both disorders may be slowly progressive and appear as a predominantly demyelinating neuropathy by electrophysiological and morphological studies. Also, both may have an elevated CSF protein concentration and may respond to immunosuppressive therapy. MAG antibodies have occasionally been found in multiple sclerosis and myesthenia gravis [2].