Clinical significance of serum interleukin-18 concentration in the patients with atopic dermatitis

Background: Interleukin (IL)-18, a potent inducer of interferon gamma (IFN-gamma), is known to have a role in diseases involving type-2 T helper cell responses including atopic dermatitis. In this study, we aimed to determine the clinical significance of serum IL-18 level in the patients with atopic dermatitis.

Methods: Serum concentration of IL-18, IFN-gamma, IgE, and blood eosinophil were measured in the patients with atopic dermatitis and healthy control subjects, and their association with the clinical score of the disease was analysed.

Results: Serum concentrations of IL-18 were significantly elevated in patients with atopic dermatitis compared to the healthy controls (332 pg/mL vs 151 pg/mL, P<0.05). Serum levels of IL-18 (r=0.41, P=0.001), eosinophil (r=0.36, P=0.003), and IgE (r=0.32, P=0.009) correlated with clinical scores in the patients. Also, multiple regression analysis indicated that serum IL-18 and IgE levels were independent predictors for the clinical score of atopic dermatitis (r2=0.25, beta=0.39, P=0.001 and beta=0.32, P=0.009).

Conclusions: Our results confirmed a significant correlation between the concentration of serum IL-18 and the severity of atopic dermatitis. Although serum IL-18 concentration reflects the disease severity, its usefulness as a clinical test needs to be further investigated, because its additive benefit over those of conventional blood tests is not evident so far.