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)alpha 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)alpha, interferon (IFN)gamma, interleukin (IL)-1 beta, 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 TNF alpha serum levels (at least once in their serial measurements). Only one was unresponsive to therapy and despite anti-TNF alpha therapy her serum TNF alpha levels remained extremely high. Two RA patients who responded to infliximab had normal TNF alpha serum levels prior to and following infliximab administration. One RA patient improved after infliximab therapy despite unrelenting high serum levels of TNF alpha, IL-6, and sIL-2R. Patients with active PsA who responded to infliximab therapy had sustained high serum TNF alpha levels. In an unselected population of RA and PsA patients, we noticed diverse patterns of serum profiles. These results imply that the cytokine profiles of RA and PsA are diverse and their pathogenesis is heterogeneous. cytokine