title: A hidden immunoglobulin G2 in patients with rheumatoid arthritis detected by nuclear magnetic resonance.
abstract: OBJECTIVE
  The ratios of immunoglobulin (Ig) G1 and IgG2 in patients with rheumatoid arthritis (RA) were examined by nuclear magnetic resonance (NMR) and the results were compared to data obtained by ELISA.
  
  
  METHODS
  The IgG of 11 patients with RA were prepared with a DE-52 column and the specific signals for IgG1 and IgG2 were measured by NMR. The ratios of IgG1 and IgG2 were determined by the intensity of this signal. The samples were also measured by ELISA.
  
  
  RESULTS
  The ratios of IgG2 in patients with RA measured by NMR were increased significantly compared to controls. However, there were no significant differences in the data determined by ELISA. Thus, a discrepancy exists in the analysis of IgG2 ratios between NMR and ELISA methods.
  
  
  CONCLUSIONS
  There was a discrepancy in the IgG2 ratios of patients with RA between NMR and ELISA methods, and we attribute this to a conformational difference in IgG2 in patients with RA.
authors.affiliation: Department of Rheumatology and Immunology, Juntendo University, School of Medicine, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tokano
authors.forename: S
authors.initials: S
authors.lastname: Endo
authors.forename: F
authors.initials: F
authors.lastname: Hayashi
authors.forename: S
authors.initials: S
authors.lastname: Harada
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: H
authors.initials: H
authors.lastname: Tsuda
authors.forename: Y
authors.initials: Y
authors.lastname: Takasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kyogoku
authors.forename: Y
authors.initials: Y
authors.lastname: Arata
authors.forename: K
authors.initials: K
authors.lastname: Okumura
authors.forename: H
authors.initials: H
authors.lastname: Hashimoto
authors.forename: S
authors.initials: S
authors.lastname: Hirose
mesh_terms: D000328:Adult; D000936:Antigen-Antibody Complex / Q000032:analysis; D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis* / Q000145:classification / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000032:analysis
chemical_list: D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D012217:Rheumatoid Factor