Anti-myelin-associated glycoprotein IgM antibody titers in neuropathy associated with macroglobulinemia.
Twenty-seven patients with neuropathy and IgM monoclonal gammopathy were tested for antigen specificity of the M-protein and for anti-myelin-associated glycoprotein (MAG) IgM levels by immunoblot. In 16 patients (59.2%) the M-protein reacted with MAG and with cross-reactive glycoconjugates. Anti-MAG IgM titers in these patients ranged between 1:12,800 and 1:100,000. A fainter IgM reactivity with MAG and related glycoconjugates was detected in 3 additional patients with neuropathy, but also in 8 of 24 patients with IgM M-protein without neuropathy (33.3%). This reactivity was not due to the M-protein and corresponded to antibody titers of 1:400 or less in all but 1 patient with a titer of 1:3,200. Low titers of anti-MAG IgM (1:200 or less) were also detected in 17 of 101 control patients without IgM M-proteins (16.8%), while 1 patient with neuropathy of unknown cause had anti-MAG IgMK titers of 1:25,600. In 1 patient with neuropathy and IgM M-protein that was not anti-MAG, the M-protein bound to other antigens in nerve, while in 6, other possible causes or mechanisms for the neuropathy were found. In this study, high titers of anti-MAG IgM antibodies were always associated with neuropathy. The presence of low levels of anti-MAG IgM in a significant proportion of controls suggests that monoclonal expansion of naturally occurring B-cell clones secreting anti-MAG IgM may be responsible for the high incidence of this antigen specificity of the M-protein.
Nobile-Orazio
E
E
Institute of Clinical Neurology, Centro Dino Ferrari, Italy.
Francomano
E
E
Daverio
R
R
Barbieri
S
S
Marmiroli
P
P
Manfredini
E
E
Carpo
M
M
Moggio
M
M
Legname
G
G
Baldini
L
L
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007148:Immunoglobulin mu-Chains / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009185:Myelin Proteins / Q000276:immunology*; D018992:Myelin-Associated Glycoprotein; D009422:Nervous System Diseases / Q000209:etiology / Q000276:immunology*; D008258:Waldenstrom Macroglobulinemia / Q000150:complications / Q000276:immunology*
D007148:Immunoglobulin mu-Chains; D009185:Myelin Proteins; D018992:Myelin-Associated Glycoprotein