Objective: Since interleukin-7 (IL-7) has been shown to induce monocyte production of IL-1, IL-6, IL-8, and tumor necrosis factor-alpha, we investigated plasma and synovial fluid levels of IL-7 in patients with juvenile rheumatoid arthritis (JRA).
Methods: IL-7 levels were measured using an ELISA in 60 patients with JRA and in 25 patients with other rheumatic disorders (ORD).
Results: In patients with systemic JRA, but not in patients with polyarticular or pauciarticular JRA or with ORD, plasma IL-7 levels were significantly higher (p < 0.0001) than those of healthy controls. IL-7 was undetected in all synovial fluid tested. Among patients with systemic JRA, those with persistent systemic symptoms had IL-7 levels significantly higher (p < 0.01) than those of patients in which systemic symptoms subsided.
Conclusion: Plasma IL-7 levels are elevated in patients with systemic JRA and are associated with the presence and severity of systemic symptoms.