Clinical immunology Effect of methotrexate on serum levels of anti-CCP antibodies and different classes of rheumatoid factors in rheumatoid arthritis patients

Background: Anti-cyclic citrullinated peptide (anti-CCP) antibodies are highly specific to rheumatoid arthritis and are predictive of rapid progression and erosive disease. There are contradictory reports on the impact of therapy on the titers of these autoantibodies and their correlation with treatment response. Objective: To investigate the effect of methotrexate treatment on anti-CCP antibodies and rheumatoid factors (RFs) in patients with rheumatoid arthritis (RA). We also analyzed whether treatment response was associated with specific changes in anti-CCP antibodies. Material and methods: The study group consisted of 44 patients with RA. All patients were treated with MTX once weekly (dose range: 10-25 mg). Disease activity was determined by the DAS 28 index and treatment response was assessed according to EULAR response criteria. Anti-CCP antibodies and IgA, IgM, and IgG RFs were tested in serum samples in methotrexate-nal..ve patients and after six months of treatment using a commercial second-generation ELISA kit. Results: The serum titers of anti-CCP antibody and IgA, and IgM RFs (but not IgG RF) decreased significantly after six months of treatment with MTX. The differences in IgA and IgM RF were most pronounced in patients with good treatment response according to EULAR criteria. Anti CCP antibodies differed significantly before and after treatment in patients with good and moderate response (p = 0.02). In patients with no response there were no significant differences. Conclusions: Methotrexate treatment of RA patients results in a decrease in the serum titers of anti-CCP antibodies and IgM and IgA RFs in patients showing clinical improvement. These parameters may be used as complementary indicators of treatment efficacy.