title: Confocal microscopic localization of anti-myelin-associated glycoprotein autoantibodies in a patient with peripheral neuropathy initially lacking a detectable IgM gammopathy.
abstract: We report here on a patient with anti-myelin-associated glycoprotein (MAG) neuropathy in whom examination of a sural nerve biopsy by multichannel confocal microscopy showed a partly overlapping distribution of MAG and IgM deposits in myelinated fibers. Our data demonstrate that MAG in Schmidt-Lanterman incisures and paranodal loops, as well as some additional HNK-1-positive components of the basal lamina, are the major targets of the anti-MAG monoclonal IgM autoantibodies in this neuropathy in vivo. Perforation of the basal lamina can allow the penetration and binding of anti-MAG IgM inside myelinated fibers. Our results support and extend the notion that the production of monoclonal anti-MAG IgM may be antigenically driven by MAG molecules and that this process may occur in the immunologically privileged environment of the nerve prior to the appearance of a genuine gammopathy in serum.
authors.affiliation: Department of Research, University Hospital Basel, Switzerland.
authors.forename: J M
authors.initials: JM
authors.lastname: Gabriel
authors.forename: B
authors.initials: B
authors.lastname: Erne
authors.forename: L
authors.initials: L
authors.lastname: Bernasconi
authors.forename: C
authors.initials: C
authors.lastname: Tosi
authors.forename: A
authors.initials: A
authors.lastname: Probst
authors.forename: L
authors.initials: L
authors.lastname: Landmann
authors.forename: A J
authors.initials: AJ
authors.lastname: Steck
mesh_terms: D001323:Autoantibodies / Q000378:metabolism*; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D018992:Myelin-Associated Glycoprotein / Q000276:immunology / Q000378:metabolism*; D010265:Paraproteinemias / Q000378:metabolism* / Q000473:pathology; D010523:Peripheral Nervous System Diseases / Q000378:metabolism* / Q000473:pathology; D013497:Sural Nerve / Q000473:pathology
chemical_list: D001323:Autoantibodies; D007075:Immunoglobulin M; D018992:Myelin-Associated Glycoprotein