Human monoclonal IgG rheumatoid factor has structural homology with bacterial Fc receptor proteins.
A cloned lymphoblast cell line, hRF-1, that secreted human monoclonal IgG4 rheumatoid factor autoantibody was produced by Epstein-Barr virus transformation of lymphocytes from rheumatoid arthritis synovium. The binding of hRF-1 rheumatoid factor to IgG globulins of different mammalian species was similar to the binding specificity of Staphylococcus aureus protein A (SpA) and to antibodies found in the sera from patients with rheumatoid arthritis. hRF-1 also had the same binding pattern to human IgG subclasses as SpA. Direct competition was observed between SpA and hRF-1 in binding IgG Fc. These results provide evidence for structural homology between a bacterial Fc receptor protein (SpA) and the monoclonal IgG rheumatoid factor.
D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000276:immunology; D002460:Cell Line; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D011961:Receptors, Fc; D012217:Rheumatoid Factor / Q000276:immunology*; D013045:Species Specificity; D013205:Staphylococcal Protein A / Q000276:immunology*
D000888:Antibodies, Anti-Idiotypic; D007074:Immunoglobulin G; D011961:Receptors, Fc; D013205:Staphylococcal Protein A; D012217:Rheumatoid Factor