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Serum interleukin 17 and interleukin 18 levels in familial Mediterranean fever

S. Haznedaroglu¹, M.A. Öztürk¹, B. Sancak², B. Goker¹, A.M. Onat³, N. Bukan², I. Ertenli³, S. Kiraz³, M. Calguneri³

¹Department of Rheumatology and ²Department of Biochemistry, Gazi University School of Medicine, Ankara; ³Department of Rheumatology, Hacettepe University School of Medicine, Ankara, Turkey.

ABSTRACT
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.

Key words
Familial Mediterranean fever, interleukin 17, interleukin 18.

This study was supported by the Gazi University Scientific Research Project Foundation.
Please address correspondence to: Dr. Mehmet Akif Öztürk, Ostim mahallesi 89. sokak, AK-84 sitesi, A-2 blok no:8, TR-06170, Yenimahalle-Ankara, Turkey.
E-mail: makifozturk@yahoo.com