Objective: Familial Mediterranean fever (FMF) attacks are characterized by serosal inflammation rich in PMNL leukocytes and activation of a definite cytokine network. Moreover, there is sustained inflammation in attack-free FMF patients. Interleukin (IL)-17 and IL-18 are recently described proinflammatory cytokines, which can modulate certain neutrophil functions. In this study we measured serum levels of IL-17 and IL-18 in FMF patients.
Methods: The study groups comprised of 18 FMF patients in attack-free period (mean age: 30.2 +/- 9.5 years; male/female: 10/8), and 18 patients with an acute FMF attack (mean age: 25.4 +/- 4.9 years; male/female: 10/8). Twenty age-matched healthy subjects were included as a control group (male/female: 10/10). Levels of IL-17 and IL-18 were determined by commercial ELISA kits (Biosource International, USA).
Results: Serum IL-17 levels were 42.8 +/- 3.7, 42.7 +/- 3.2, and 39.9 +/- 2.3 pg/mL for FMF patients in attack-free period, FMF patients with acute attack, and healthy controls, respectively. Serum IL-18 levels were 878.8 +/- 315.0, 854.2 +/- 261.4, and 314.6 +/- 80.8 pg/mL for FMF patients in an attack-free period, FMF patients with acute attack, and healthy controls, respectively. Levels of both IL-17 and IL-18 were significantly higher in FMF patients with and without acute attack compared to control group (p < 0.05). Concentrations of those cytokines were comparable in FMF patients with acute attack and in attack-free period (p > 0.05).
Conclusion: Our data suggest that IL-17 and IL-18 contribute to the cytokine network in the inflammatory cascade of FMF. However, their roles for the initiation of FMF attacks remain to be established.