Determination of the affinity of monoclonal human IgM for myelin-associated glycoprotein and sulfated glucuronic paragloboside.
We determined the association constant of eight monoclonal IgM with two of their targets, i.e. the myelin-associated glycoprotein (MAG) or the sulfated glucuronic paragloboside (SGPG). All IgM had a 10- to 100-fold higher affinity for MAG than for SGPG. The affinity of the different IgM for MAG ranged from 1.3 x 10(-6) to 7 x 10(-9) mol/liter. The Scatchard plots for MAG were curvilinear, half of the sites being of high or low affinity. In contrast, the plots were linear in the assay using SGPG. No obvious correlations were found between the fine specificity of these IgM for the glucuronyl sulfate epitope and their affinity, although most IgM with a high affinity reacted exclusively with SGPG derivatives retaining a sulfate group. There was no parallelism between the severity of the neuropathy and the affinity of the IgM for MAG or SGPG.
Laboratory of Immunology and Immunopathology, U.108 INSERM, Hôpital Saint-Louis, Paris, France.
J C
JC
Brouet
X
X
Mariette
A
A
Chevalier
B
B
Hauttecoeur
D005915:Globosides / Q000378:metabolism*; D005965:Glucuronates / Q000378:metabolism; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism*; D009185:Myelin Proteins / Q000378:metabolism*; D018992:Myelin-Associated Glycoprotein; D010523:Peripheral Nervous System Diseases / Q000209:etiology
D005915:Globosides; D005965:Glucuronates; D007075:Immunoglobulin M; D009185:Myelin Proteins; D018992:Myelin-Associated Glycoprotein; C036363:paragloboside