Objective: To evaluate serum and synovial fluid (SF) levels of macrophage migration inhibitory factor (MIF) and in vitro MIF production by peripheral blood mononuclear cells (PBMCs) in patients with juvenile idiopathic arthritis (JIA).
Methods: Serum, SF, and culture supernatant levels of MIF were measured by enzyme-linked immunosorbent assay. Production of MIF by PBMCs was investigated by culturing PBMCs in the absence or presence of 2 different concentrations of concanavalin A.
Results: Serum MIF levels were increased in patients with JIA, and the highest levels were present in patients with systemic-onset JIA. In systemic-onset JIA, serum levels of MIF correlated with the persistence of systemic features and the number of active joints. PBMCs from patients with systemic-onset JIA, when cultured under unstimulated conditions or at suboptimal stimulation, released higher amounts of MIF compared with those from patients with oligoarticular-onset JIA or healthy controls. MIF levels in the SF of patients with systemic-onset JIA were significantly higher than those in patients with oligoarticular-onset JIA. In individual joints, in both systemic-onset JIA and oligoarticular-onset JIA, SF MIF levels were inversely correlated with the duration of the clinical remission induced by intraarticular administration of triamcinolone hexacetonide.
Conclusion: MIF appears to be a relevant cytokine in the pathogenesis of JIA, particularly in systemic-onset JIA.