IL-18 mRNA expression and IFN-g induction in bronchoalveolar lavage from Behçet's disease 

A. Hamzaoui1,3, H. Ghraïri1,3, J. Ammar1,3, S. Zekri3, F. Guemira2, K. Hamzaoui3

1Department of Respiratory Diseases, Pneumology Hospital A. Mami, Ariana; 2Biochemical and Oncology Laboratory and 3Homeostasis and Cell Dysfunction Unit Research, Medicine University of Tunis, Tunis, Tunisia.

ABSTRACT
Objective
IL-18 expression and functional activity has been identified in several autoimmune and infectious diseases. To clarify the potential role of IL-18 during pulmonary Behçet's disease (BD), we have explored the capacity of IL-18 to induce the expression of IFN-g.

Methods
We studied bronchoalveolar lavage (BAL) from 12 patients with BD, 10 patients with silicosis as the control disease and 10 BAL from healthy subjects. BAL fluid, and BAL fluid cell cultures were investigated for IL-18 estimation by ELISA. Analysis of IL-18 and IFN-g gene expression was carried out before and after LPS stimulation. 

Results
BD patients had significantly elevated levels of IL-18 in BAL fluid compared with control disease and healthy subjects. Induction of IFN-g and IL-18 were observed from BD-BAL fluid cells both spontaneously and after LPS stimulation, at higher levels compared to silicosis patients and healthy subjects (HC). Spontaneously only BD BAL cells expressed IL-18 mRNA and IFN-g mRNA. Forty-eight hours after LPS stimulation IL-18 mRNA and IFN-g mRNA were observed in BD, silicosis and HC cells. Recombinant IL-18 induced IFN-g production in BD- BAL fluid cells. 

Conclusion
Administration of IL-18 induced greater IFN-g production in BD-BAL fluid cells, than in normal BAL fluid cells. Our data indicate that IL-18 up-regulation is a feature of BD and suggest that IL-18 and IFN-g may contribute to the local inflammatory response in BD.

Key words
Behçet's disease, inflammation, cytokines, Th1, IL-18, IFN-g.

Please address correspondence to: Kamel Hamzaoui, MD, Medicine University Tunis, 15 Rue Djebel Lakhdar Bab Saadoun, 1007 Tunis, Tunisia. 
E-mail: Kamel.Hamzaoui@fmt.rnu.tn

Clin Exp Rheumatol 2003; 21: (Suppl. 30): S4-S14.
© Copyright Clinical and Experimental Rheumatology 2003.