Changes in anti-citrullinated protein antibody titers following treatment with infliximab for rheumatoid arthritis.

BACKGROUND: The presence of anti-citrullinated peptide/ protein antibody (ACPA) has a high specificity and predictive value for the development of rheumatoid arthritis (RA). Some studies have shown decreased titers of this antibody after treatment with infliximab. OBJECTIVES: To assess the changes in ACPA titers in patients with RA after treatment with infliximab as a first biological agent, and to correlate these variations with non-infusion-related adverse effects. METHODS: In a prospective multicenter observational study involving 48 research centers, we assessed 139 patients with established moderate-to-severe RA diagnosed according to American College of Rheumatology criteria. Samples were collected before and 6-12 months after treatment. RESULTS: The mean age of the study patients was 50.6 years and 118 were female (84.9%). Statistically significant variations in ACPA titers were noted in 47 patients (before and after treatment) (P = 0.012). Overall, ACPA titers were decreased in 32 (65.3%) and increased in 15 (34.7%). No correlation was found between severe or mild adverse effects in patients presenting variations in ACPA titers. CONCLUSIONS: The present study showed that infliximab affected ACPA titers, promoting mainly a decrease; however, this was not related to the occurrence of non-infusion-related adverse effects.