Induction of autoantibodies in refractory rheumatoid arthritis treated by infliximab.

Objectives: To investigate autoantibody induction in rheumatoid arthritis (RA) patients treated with infliximab.

Methods: We included 59 refractory RA patients treated with infliximab in combination with low-dose prednisone and methotrexate or leflunomide. We tested the sera of the patients for antinuclear antibodies (ANA), rheumatoid factor (RF), anti double-stranded DNA antibodies (anti dsDNA), anti-histone and anti-extractable nuclear antigen antibodies (aENA) at baseline and before infusion at weeks 6 and 30. Infliximab, initiated at a dose of 3 mg/kg, was increased to 5 mg/kg if insufficient improvement was observed after three infusions.

Results: At week 6, only the frequency of anti-histone IgM antibody-positive patients had significantly increased (19 vs 42%, p = 0.009). At week 30, the frequency of patients with ANA had increased from 29% to 69% (p < 0.001), that of patients with anti-dsDNA antibodies had increased from 0% to 3% for IgG (NS) and from 0% to 32% for IgM (p < 0.001); the frequency of antihistone IgG detection had increased from 22% to 32% (p = 0.04) and that of IgM detection, from 18% to 79% (p < 0.001). No lupus-like syndrome was observed. RF decreased significantly (87 IU to 52.5 IU, from baseline to week 30; p < 0.001). No significant difference was observed between the 16 non-responders and the responders, in terms of autoantibody status at baseline and changes with infliximab therapy.

Conclusion: Infliximab therapy lead to the selective and delayed induction of autoantibodies. This induction was not associated with clinical symptoms until week 30 and did not differ between responders and non-responders.