title: The distinct subgroup of patients with rheumatoid arthritis shown by Ig G3-reactive rheumatoid factor.
abstract: The reactivity of rheumatoid factor (RF) with immunoglobulins of the IgG3 subclass was examined in 49 patients with rheumatoid arthritis (RA) using two types of IgG3 myeloma (routine and IgG3m-15 allotype). Among 49 patients, serum from eight cases showed positive reactivity with both types of IgG3 myeloma by radio-immunoassay (RIA). The isotype of IgG3-reactive RF was not specific; it belonged to the IgM class as well as the IgG subclasses IgG1, IgG2 and IgG4. The patients with IgG3-reactive RF belonged to the clinically-severe classification of RA, having a high erythrocyte sedimentation rate (ESR), high titre in the RA hemagglutination (RAHA) test, and above all they had low levels of complement. Generally, it is concluded that patients with IgG3-reactive RF have serious arthritis and that IgG3-reactive RF might play an important role in the inflammatory process. Furthermore, it was also shown that the RF-reactive site was not associated with the protein-A binding site of IgG3, since RF reacting with IgG3m-15 reacted similarly with routine IgG3, regardless of the difference of the protein-A binding activity. This was confirmed by adding protein-A to the reaction of RF and IgG3m-15 which binds with protein-A. This suggests that the actual reactive site of RF is different to the site that binds protein-A.
authors.affiliation: Department of Internal Medicine, Juntendo University, School of Medicine, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tokano
authors.forename: S
authors.initials: S
authors.lastname: Arai
authors.forename: H
authors.initials: H
authors.lastname: Hashimoto
authors.forename: S
authors.initials: S
authors.lastname: Hirose
authors.forename: H
authors.initials: H
authors.lastname: Yagita
authors.forename: H
authors.initials: H
authors.lastname: Nakauchi
authors.forename: Y
authors.initials: Y
authors.lastname: Kumagai
authors.forename: Y
authors.initials: Y
authors.lastname: Arata
authors.forename: K
authors.initials: K
authors.lastname: Okumura
mesh_terms: D000328:Adult; D000368:Aged; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D001172:Arthritis, Rheumatoid / Q000145:classification* / Q000276:immunology; D005260:Female; D006386:Hemagglutination Tests; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D007132:Immunoglobulin Isotypes / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009194:Myeloma Proteins / Q000276:immunology; D011961:Receptors, Fc / Q000276:immunology*; D012217:Rheumatoid Factor / Q000276:immunology*; D012720:Severity of Illness Index; D013205:Staphylococcal Protein A
chemical_list: D000888:Antibodies, Anti-Idiotypic; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M; D009194:Myeloma Proteins; D011961:Receptors, Fc; D013205:Staphylococcal Protein A; D012217:Rheumatoid Factor