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.