Abstract: Objective To evaluate the significance of human interleukin-31 （IL-31） in the pathogenesis of atopic dermatitis and its correlation with pruritus in patients with atopic dermatitis （AD）. Methods Twenty-two children with mild to severe atopic dermatitis and 22 age-matched healthy controls were included in this study. Patients and controls were randomly and equally assigned into stimulation and non-stimulation groups. Venous blood samples were obtained from all participants, peripheral blood mononuclear cells were isolated from these samples and cultured with （stimulation groups） or without （non-stimulation groups） staphylococcal enterotoxin B （SEB） for 24 hours. Then, the mRNA expression of IL-31 on PBMCs was assessed via real-time reverse transcription-PCR. ELISA was used to detect the total serum IgE level in these objects. The severity of AD in patients was rated according to scoring atopic dermatitis （SCORAD）. The relationship between the mRNA expression of IL-31 and the level of serum total IgE, severity of atopic dermatitis, and degree of pruritus, was evaluated. Results The expression of IL-31 mRNA on non-stimulated PBMCs from patients was 23.2 folds as high as that from the healthy controls （P < 0.01）. The stimulation with SEB upregulated the mRNA expression of IL-31 on PBMCs, and the increase on PBMCs from patients was 20.44 times of that from the controls. The total serum IgE level was 260.05 IU/mL （5.9 - 1131.01 IU/mL） and 17.7 IU/mL （5 - 140.7 IU/mL） in the patients and controls respectively （P < 0.01). There was no significant correlation between the mRNA expression of IL-31 and disease severity or total serum IgE level （r = 0.07, 0.22 respectively, both P > 0.05） in patients with AD. Conclusions IL-31 is involved in the pathogenesis of AD, which is unlikely to be IgE-dependent. SEB can induce the rapid expression of IL-31 on PBMCs of healthy human, and is an important modulator for the production of IL-31.

Key words: atopic dermatitis, Interleukin-31, pruritus