To investigate the effect of oral methotrexate (MTX) on circulating levels of interleukin 6 (IL-6) and soluble IL-2 receptor (sIL-2R) in patients with rheumatoid arthritis (RA).
We measured serum concentrations of IL-6 (n = 20) and sIL-2R (n = 16) before MTX therapy and again after 12 weeks.
MTX significantly reduced IL-6 and sIL-2R after 12 weeks of therapy, and although the levels remained low at 24 weeks of therapy, the reduction was not significant. Reduction in cytokine levels was paralleled by an improvement in clinical indices. Placebo treatment did not significantly alter IL-6 or sIL-2R.
MTX appears capable of cytokine modulation, although the mechanism is not clear.