BACKGROUND: The introduction of tumor necrosis factor (TNF) antagonists (adalimumab, infliximab, and etanercept) was a major advance and was highly important and beneficial in most rheumatoid arthritis (RA) patients. The adverse effects of this treatment are infrequent, but include opportunistic intracellular infection (especially the reactivation of latent Mycobacterium tuberculosis); exacerbation of demyelinating disorders; and the production of various types of antibodies such as antinuclear antibodies (ANA) or double-stranded DNA autoantibodies (dsDNA) and antiphospholipid antibodies (aPL) such as anti-cardiolipin antibodies (aCL) and anti-B2GP-I antibodies (B2GP-I). The aim of the study was to determine the prevalence of aCL and B2GP-I in IgM and IgG classes, using ELISA tests, during 6 months of follow-up in patients with refractory RA successfully treated with infliximab.

MATERIAL AND METHODS: We determined the prevalence of aCL and B2GP-I in IgM and IgG classes, using ELISA tests, during 6 months of follow-up in patients with refractory RA successfully treated with infliximab.

RESULTS: We observed a statistically important increase only in the group of B2GP-I IgM (p<0.05). There are contradictory results concerning the ability of infliximab to induce aPL, but most authors confirm this phenomenon.

CONCLUSIONS: Further investigations are needed to determine if the new aPL appears in patients with β2-GPI gene polymorphisms such as leucine-to-valine substitution at position 247, which can lead to a conformational changes in β2-GPI protein, leading to aPL synthesis. The role of aPL in pathogenesis of APS is still unclear, but we should remember the immunogenic aspect of TNF antagonist treatment. Therefore, we recommend early detection of aPL and observation of the patient, paying special attention to signs and symptoms of thromboembolism.

Keywords: Antibodies, Antiphospholipid - blood, Antibodies, Monoclonal - pharmacology, Arthritis, Rheumatoid - drug therapy, Cardiolipins - immunology, Enzyme-Linked Immunosorbent Assay, Follow-Up Studies, Methotrexate - pharmacology, Time Factors, Tumor Necrosis Factor-alpha - antagonists & inhibitors, beta 2-Glycoprotein I - immunology