title: Development of antiinfliximab antibodies and relationship to clinical response in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  Treatment of patients with infliximab, a chimeric monoclonal IgG1 antibody against tumor necrosis factor, may result in the formation of infliximab-specific IgG antibodies. This study evaluated the clinical significance of these antibodies in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Antiinfliximab antibodies were measured using a newly developed radioimmunoassay in a cohort of 51 consecutive patients with RA treated with infliximab, with a followup of 1 year. In addition, serum infliximab levels were determined by enzyme-linked immunosorbent assay. The results were analyzed in relation to the clinical response to treatment according to the European League Against Rheumatism criteria.
  
  
  RESULTS
  Antibodies against infliximab were detected in 22 patients (43%). Patients without detectable antiinfliximab antibodies (n = 29 [57%]) were significantly more often classified as responders (20 of 29 [69%]) compared with patients with detectable antiinfliximab antibodies (8 of 22 [36%]; P = 0.04). Three patients had an infusion-related allergic reaction, all of whom had detectable antiinfliximab antibodies.
  
  
  CONCLUSIONS
  In this study, nearly half of the RA patients treated with infliximab developed antiinfliximab antibodies within the first year of treatment. This seems to be clinically relevant, since development of antiinfliximab antibodies is associated with a reduced response to treatment.
authors.affiliation: Department of Immunopathology, CLB Sanquin Amsterdam and Jan van Breeman Institute, Amsterdam, The Netherlands. G.Wolbink@janvanbreeman.nl
authors.forename: Gerrit Jan
authors.initials: GJ
authors.lastname: Wolbink
authors.forename: Marijn
authors.initials: M
authors.lastname: Vis
authors.forename: Willem
authors.initials: W
authors.lastname: Lems
authors.forename: Alexandre E
authors.initials: AE
authors.lastname: Voskuyl
authors.forename: Els
authors.initials: E
authors.lastname: de Groot
authors.forename: Michael T
authors.initials: MT
authors.lastname: Nurmohamed
authors.forename: Steven
authors.initials: S
authors.lastname: Stapel
authors.forename: Paul P
authors.initials: PP
authors.lastname: Tak
authors.forename: Lucien
authors.initials: L
authors.lastname: Aarden
authors.forename: Ben
authors.initials: B
authors.lastname: Dijkmans
mesh_terms: D000906:Antibodies / Q000097:blood; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000627:therapeutic use*; D000917:Antibody Formation; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology*; D005260:Female; D006801:Humans; D000069285:Infliximab; D008297:Male; D011863:Radioimmunoassay
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D000069285:Infliximab