Impact of treatment with infliximab on serum cytokine profile of patients with rheumatoid and psoriatic arthritis

This article analyzes the serum cytokine profile of a nonrandomized group of patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA) who are destined to be treated with infliximab following failure after failure of different disease-modifiying antirheumatic drugs (DMARDs). Serial serum samples were collected from 11 patients with refractory RA, three with PsA and one with undifferentiated spondyloarthropathy. All were treated with the antitumor necrosis factor (TNF)α agent, infliximab, after failing to sustain a clinical remission with conventional DMARDs. Blood samples were obtained at different phases of their therapy. Serum levels of tumor necrosis factor (TNF)α, interferon (IFN)γ, interleukin (IL)-1β, IL-6, sIL-2R, IL-10, and IL-1 receptor antagonist (IL-1RA) were determined by commercial ELISA kits. Interestingly, only eight of the 11 patients with RA had elevated TNFα serum levels (at least once in their serial measurements). Only one was unresponsive to therapy and despite anti-TNFα therapy her serum TNFα levels remained extremely high. Two RA patients who responded to infliximab had normal TNFα serum levels prior to and following infliximab administration. One RA patient improved after infliximab therapy despite unrelenting high serum levels of TNFα, IL-6, and sIL-2R. Patients with active PsA who responded to infliximab therapy had sustained high serum TNFα levels. In an unselected population of RA and PsA patients, we noticed diverse patterns of serum cytokine profiles. These results imply that the cytokine profiles of RA and PsA are diverse and their pathogenesis is heterogeneous.