Binding of human IgM from a rheumatoid factor to IgG of 12 animal species.
The binding of IgM from a rheumatoid factor (RF-IgM) to IgG from 12 animal species was analyzed by an ELISA system. The RF-IgM bound various animal IgG with dissimilar affinities. The binding of RF-IgM to animal IgG was inhibited by addition of protein A, which binds some animal IgG by recognizing the junctional site on CH2-CH3 domains in the Fc region. As previously reported, no significant correlation was observed between the binding of RF-IgM to IgG and the content of galactose-free oligosaccharides, which is increased in IgG of rheumatoid arthritis patients or autoimmune mice. We suggest that the crucial epitope of IgG for RF-IgM binding is not the oligosaccharide structure generated specifically in IgG of autoimmune diseases but that RF-IgM may recognize a certain protein conformation of a region in IgG near the binding site of protein A.
Hamako
J
J
Division of Biomedical Polymer Science, Fujita Health University, Toyoake, Japan.
Ozeki
Y
Y
Matsui
T
T
Yamamoto
Y
Y
Inoue
T
T
Yukitake
J
J
Titani
K
K
D000818:Animals; D001665:Binding Sites; D002645:Chickens / Q000097:blood* / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008322:Mammals / Q000097:blood* / Q000276:immunology; D011485:Protein Binding; D012217:Rheumatoid Factor / Q000097:blood*; D013205:Staphylococcal Protein A / Q000097:blood
D007074:Immunoglobulin G; D007075:Immunoglobulin M; D013205:Staphylococcal Protein A; D012217:Rheumatoid Factor