John Libbey Eurotext

European Cytokine Network


Serum and urinary levels of IL-18 and its inhibitor IL-18BP in systemic lupus erythematosus Volume 21, numéro 4, December 2010

Clinical Immunology Unit, Department of Internal Medicine, University of Pisa, Pisa, Italy, Immunobiology Unit, Institute of Biomedical Technologies, National Research Council, Pisa, Italy, Dept. Infectious Diseases, University of Colorado Medical School, Denver, CO, USA

Overproduction of inflammation-related cytokines plays an important role in systemic lupus erythematosus (SLE). A crucial cytokine is IL-18, a member of the IL-1 family involved in the regulation of both innate and acquired immune responses. The aim of this study was to evaluate free IL-18 levels in the serum and urine of SLE patients, in order to establish their relationship with other biomarkers of disease activity. Serum and urine levels of IL-18 and IL-18BP were measured by ELISA in 50 SLE patients and in 32 healthy subjects; free IL-18 was calculated using the law of mass action. Serum levels of total IL-18, IL-18BP and free IL-18 were higher in SLE patients than in healthy controls. Total and free serum IL-18 levels were higher in patients with active disease (with nephritis or active non-renal disease), and correlated with the ECLAM score. Urinary levels of total and free IL-18 were higher in patients than in controls, but did not correlate with disease activity. The data collected in this study show that increased levels of both IL-18 and its natural inhibitor IL-18BP, characterise SLE. Despite the overproduction of IL-18BP, free IL-18 is still significantly higher in SLE patients than in controls, and its serum levels are a marker of disease activity.