Clinical Significance of Serum Interleukin-18 Concentration in the Patients with Atopic Dermatitis

Do-Sim Park; Young-Hoon Youn

doi:10.3343/kjlm.2007.27.2.128

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Park and Youn: Clinical Significance of Serum Interleukin-18 Concentration in the Patients with Atopic Dermatitis

Original Article

Korean J Leg Med 2007;27(2):128-132.

Published online: 10 February 2007

DOI: https://doi.org/10.3343/kjlm.2007.27.2.128

Clinical Significance of Serum Interleukin-18 Concentration in the Patients with Atopic Dermatitis

Do-Sim Park, M.D.^1,³, Young-Hoon Youn, M.D.^2,³

¹Department of Laboratory Medicine, School of Medicine, Wonkwang University, Iksan, Korea

²Department of Dermatology, School of Medicine, Wonkwang University, Iksan, Korea

³Department of Institute of Wonkwang Medical Science, School of Medicine, Wonkwang University, Iksan, Korea

Received 27 October 2006 Revised 29 January 2007 Accepted 29 January 2007

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Interleukin (IL)-18, a potent inducer of interferon gamma (FN-γ), 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-γ, 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, β=0.39, P=0.001 and β=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.

Keywords: Interleukin 18, Atopic dermatitis, Cytokine

References

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Fig. 1.

Mean concentrations (rectangles) and 95% confidence intervals (error bars) of blood eosinophil, IgE, IL-18, and IFN-γ in healthy controls, total atopic dermatitis (AD), and each disease grade group (mild, moderate, and severe) of AD.

Fig. 2.

ROC curve analysis for the screening efficiency of serum IL-18.

Table 1.

Characteristics of atopic dermatitis patients and healthy controls

	Atopic dermatitis (SCORAD range)				Controls
	Total	Mild (<25)	Moderate (25–50)	Severe (>50)	Controls
Number	65	15	20	30	61
Age (yr)	15±10	14±8	14±9	17±10	19±7
	(2–41)	(6–37)	(2–30)	(2–41)	(3–39)
Sex (M/F)	43/22	9/6	11/9	23/7	40/21
SCORAD	45	19	36	63
index	(40–50)	(18–21)	(34–39)	(59–67)

Age (yr) is shown as the mean±1SD and range. The levels of SCO-RAD index are presented as mean and 95% confidence interval for mean.

Abbreviation: NS, not significant.

Table 2.

Correlation among clinical severity and blood markers evaluated by Pearson correlation

		SCORAD	IL-18	Eosinophil counts	IgE
IL18	r	0.41
	P	0.001^*
Eosinophil counts	r	0.36	0.41
	P	0.003^*	0.001^*
IgE	r	0.32	0.01	0.13
	P	0.009^*	NS	NS
INF-γ	r	0.07	0.02	0.16	0.13
	P	NS	NS	NS	NS

^* P<0.05.

Abbreviation: NS, not significant.

Table 3.

Multiple linear regression analysis evaluating the independent factors for clinical severity of atopic dermatitis patients

Model	r²	Predictor	SCORAD Coefficients (β)	P
A	0.16	IL-18	0.39	0.002
B	0.25	IL-18	0.39	0.001
		IgE	0.32	0.009

Excluded variables are age, sex, eosinophil, IgE, and IFN-r in model A; and age, sex, eosinophil, and IFN-γ in model B by stepwise linear regression.

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