BUDAPEST, HUNGARY — While infliximab therapy for the treatment of rheumatoid arthritis lowers rheumatoid factor titers, the biologic appears to have little effect on another increasingly relevant marker of disease activity: anticyclic citrullinated peptide antibodies, Nathalie Bardin, M.D., said at the 4th International Congress on Autoimmunity.
“The long-term effect of infliximab therapy leads to a reduction in rheumatoid factor titers and the induction of IgG anti-double-stranded DNA [anti-dsDNA].” Yet there was no change in anticyclic citrullinated peptide (anti-CCP) levels,” said Dr. Bardin of Hôpital de la Conception, Marseille, France.
In a study of 33 rheumatoid arthritis (RA) patients, 20 treated with infliximab (Remicade), 13 untreated, and 20 controls with undetermined arthritis, the researchers measured levels of anti-CCP, anti-dsDNA antibodies, and IgM rheumatoid factor (RF).
Anti-CCP antibodies were identified in 70% of RA patients, regardless of treatment, but only 10% of those with undetermined arthritis. RF was found in 60% of RA patients but only 10% of the controls. The frequency of RF was 55% in treated patients compared with 69% in untreated patients.
Dr. Bardin also followed 16 RA patients over 2 years of infliximab therapy. No change in anti-CCP level was found, but there was a drop in RF titers, she said. “IgG anti-dsDNA was only detected in patients treated with infliximab.” Because of its high specificity and sensitivity, anti-CCP antibody testing is increasingly seen as an important marker of disease activity in RA patients.
In a study of 54 patients with early RA, 35 patients with established RA, 33 healthy donors, and 76 patients with non-RA autoimmune diseases, researchers at the University of Florence (Italy) confirmed that the presence of anti-CCP antibodies is specific to the diagnosis of RA and is also an indicator of bone lesions (Autoimmunity 2004;37:495-501).