Study of urinary leukotriene E4 in atopic dermatitis: relation to disease severity

Abstract

Background: Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease prevalent in patients with a personal or family history of atopy. Cysteinyl leukotrienes (LTs) are inflammatory mediators which play a role in the pathogenesis of atopic diseases. Urinary leukotriene E4 (LTE4) has been used as an index of the whole body cysteinyl LTs production. Objective: This study was meant to evaluate the importance of LTs in atopic dermatitis (AD) and to study the correlation of urinary LTE4 with disease severity and some commonly altered parameters in AD. Methods: The study included 30 children and adolescents diagnosed to have atopic dermatitis. Ten age and sex matched healthy children and adolescents were enrolled for comparison. They were subjected to clinical evaluation and measurement of urinary LTE4, absolute eosinophilic count, serum IgE and IL-4 and IL-5 in peripheral blood mononuclear cell culture (PBMC) supernatant. The patients were categorized into mild (n=5), moderate (n=16) and severe (n=9) AD subgroups. Results: The study revealed a significant increase in absolute eosinophilic count, urinary LTE4, serum IgE and IL-4 and IL-5 in PBMC culture supernatant in the patients as compared to controls. Moreover, urinary LTE4 levels were significantly increased in moderate and severe cases of AD as compared to the control group, whereas mild cases had levels that were comparable to the controls. Urinary LTE4 levels were higher in severe (p < 0.01) and moderate cases (p < 0.05) when compared to mild cases. Significant positive correlations could be elicited between urinary LTE4 and PBMC IL-4, disease severity scale, absolute eosinophilic count and serum total IgE. However, urinary LTE4 could not be correlated statistically with PBMC IL-5. Conclusion: Elevation in urinary LTE4 excretion in AD patients was demonstrated reflecting increased production of cysteinyl LTs. Urinary LTE4 was correlated to clinical and laboratory markers of severity suggesting that it could be an easy, non invasive and objective prognostic test in AD. Trials of 5-lipoxygenase inhibitors and LT receptor antagonists as additional lines of therapy in AD could thus be suggested.

Keywords: atopic dermatitis, urinary LTE4, IgE, IL-4, IL-5, eosinophilic count

Egypt J Pediatr Allergy Immunol 2003; 1(2): 134-9