Confocal microscopic localization of anti-myelin-associated glycoprotein autoantibodies in a patient with peripheral neuropathy initially lacking a detectable IgM gammopathy.
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.
Gabriel
J M
JM
Department of Research, University Hospital Basel, Switzerland.
Erne
B
B
Bernasconi
L
L
Tosi
C
C
Probst
A
A
Landmann
L
L
Steck
A J
AJ
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
D001323:Autoantibodies; D007075:Immunoglobulin M; D018992:Myelin-Associated Glycoprotein