Infliximab Reduces the Frequency of Interleukin 17-Producing Cells and the Amounts of Interleukin 17 in Patients With Rheumatoid Arthritis

Background: To detect frequency changes in interleukin 17 (IL-17)(+) CD4(+) T cells and the amounts of IL-17 in supernatants between baseline and 30 weeks after Infliximab combined with methotrexate (MTX) or MTX-alone therapy. Methods: Flow cytometry was used to analyze the frequency of IL-17(+) CD4(+) T cells in rheumatoid arthritis (RA) patients and control subjects at baseline and 30 weeks after therapy. Secretion of IL-17 by peripheral blood mononuclear cells was measured by enzyme-linked immunosorbent assay. Results: The percentages of IL-17(+) CD4(+) T cells were increased in the peripheral blood mononuclear cells of patients with RA compared with healthy subjects. The percentages of IL-17(+) CD4(+) T cells were correlated with the number of swelling joints and C-reactive protein of RA patients. Likewise, concentrations of IL-17 in supernatants from patients with RA were significantly higher compared with those from control subjects. After infliximab combined with MTX or MTX-alone therapy, the number of swelling joints, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and Disease Activity Score 28 decreased significantly compared with baseline. Only in the infliximab + MTX group that the frequency of T(H)17 cells and concentration of IL-17 decreased. Conclusions: These data support the hypothesis that infliximab therapy can have an effect on T(H)17 cells and decrease disease activity.