Objectives To examine the evolution of the ANA titre in patients with rheumatoid arthritis treated with infliximab (anti TNF- alpha).

Methods 14 patients with active rheumatoid arthritis and unresponsive to at least 3 DMARDs were treated with methotrexate and infliximab. Before infliximab infusion, weeks 0, 2,6,14 and 22, a physical examination, DAS 28 and blood test, which included RF, ANA, immunoglobulin quantification C3 and C4 were done.

Results At the baseline visit 5/14 (35,71%) patients had positive ANA test,2 (1/40),1 (1/80),1 (1/160), 1 (1/640). After the fifth infusion 8/14 (57,14%) had a positive ANA test. Three patients who initially were ANA negative showed a titre of 1/160,1/320 and 1/640. Three out of 5 patients which previously had a positive test, showed an increase in the ANA titre,1/40 to 1/80,1/40 to 1/320 and 1/640 to 1/1280. After the fourth infusion of infliximab, all patients with ANA positive had a Crithidia test performed. In all cases anti DNA were negative.

Conclusion In our experience, treatment with infliximab has shown an increase of the ANA titre in 21,42% of the patients. On the other hand, 21,4% of the patients with a previous negative test for ANA had a positive test after the fourth infusion. All cases were negative for anti-DNA antibodies.