title: Assessment of antibodies to double-stranded DNA induced in rheumatoid arthritis patients following treatment with infliximab, a monoclonal antibody to tumor necrosis factor alpha: findings in open-label and randomized placebo-controlled trials.
abstract: OBJECTIVE
  To compare the incidence of anti-double-stranded DNA (anti-dsDNA) antibodies in rheumatoid arthritis (RA) patients receiving either single or multiple doses of a chimeric anti-tumor necrosis factor alpha (anti-TNFalpha) antibody or placebo infusions, with or without methotrexate, in open-label, randomized, placebo-controlled trials.
  
  
  METHODS
  Multiple sera obtained from 156 patients before and after treatment with infliximab and from 37 patients treated with placebo infusions were tested for anti-dsDNA antibodies by 3 methods: Crithidia luciliae indirect immunofluorescence test (CLIFT), a commercial Farr assay (Ortho Diagnostics radioimmunoassay [RIA]) in which the antigen source is mammalian DNA, and a Farr assay employing 125I-labeled circular plasmid DNA (Central Laboratory of The Netherlands Red Cross Blood Transfusion Service [CLB] RIA). Patients with positive findings on the CLIFT were also tested for antibodies to histones (H1-H5) and chromatin and for IgM rheumatoid factors (IgM-RFs).
  
  
  RESULTS
  None of the RA patients had a serum sample that was positive for anti-dsDNA antibodies by the CLIFT prior to infliximab therapy. Of the 22 patients who developed a positive CLIFT result, 11 (7% of 156 exposed to infliximab) also had positive findings on the Ortho RIA at a concentration of >10 units/ml and another 8 (5%) were positive at a concentration of >25 units/ml. In all but 1 patient, the anti-dsDNA antibodies were solely of the IgM isotype. Only 1 patient had detectable anti-dsDNA antibodies by the CLB RIA. All sera containing anti-dsDNA by the CLIFT contained antibodies to chromatin, and sera from 2 patients also contained antibodies to histones. IgM-RF titers showed a significant reduction following infliximab therapy in these 22 patients. One patient developed anti-dsDNA antibodies of IgG, IgA, and IgM isotype and had positive results on both Farr assays (peaking at 22 weeks and resolving by 54 weeks); this was associated with a reversible lupus syndrome.
  
  
  CONCLUSIONS
  Anti-dsDNA antibodies of IgM class are induced by infliximab therapy; the frequency is dependent on the assay method used. Only 1 of the 156 patients who were treated with infliximab developed a self-limiting clinical lupus syndrome; that patient developed high titers of anti-dsDNA antibodies of IgG, IgM, and IgA class, as detected by the CLIFT and by 2 different Farr assays.
authors.affiliation: Kennedy Institute of Rheumatology, London, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Charles
authors.forename: R J
authors.initials: RJ
authors.lastname: Smeenk
authors.forename: J
authors.initials: J
authors.lastname: De Jong
authors.forename: M
authors.initials: M
authors.lastname: Feldmann
authors.forename: R N
authors.initials: RN
authors.lastname: Maini
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000188:drug therapy*; D004247:DNA / Q000276:immunology; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D000069285:Infliximab; D008180:Lupus Erythematosus, Systemic / Q000097:blood; D016032:Randomized Controlled Trials as Topic; D012217:Rheumatoid Factor / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D018501:Antirheumatic Agents; D007075:Immunoglobulin M; D014409:Tumor Necrosis Factor-alpha; D004247:DNA; D012217:Rheumatoid Factor; D000069285:Infliximab