Role of Antigen-Induced Cytokine Release in Atopic Pruritus

Abstract

In order to further evaluate the role of cytokines in the induction of atopic pruritus, leukocytes from 10 atopic eczema patients or 10 nonallergic controls were stimulated in vitro with mite or birch pollen antigen for 1 and 4 days. Subjects were prick-tested with the supernatants, and whealing and itching were evaluated 20 and 60 min later. The supernatants were also examined for the contents of GM-CSF, IL-2, IL-6 and IL-8 by ELISA and TNFα. Two hours prior to testing, the antihistamine cetirizine (20 mg) or a placebo tablet were given to the patients according to a randomized, double-blind study protocol. After pricking with antigen-stimulated leukocyte supernatants, 6 of 10 patients but no controls reacted mostly at 20 min with whealing and/or pruritus. In the cetirizine-treated group, no decrease in these skin reactions was seen compared to placebo. Analysis for cytokines showed increased levels of IL-8 in allergen-stimulated samples, with no correlation to the induction of itching or whealing by these supernatants. IL-6 levels were low and variable, and GM-CSF, IL-2 and TNFα levels were always below standard values. These data show that leukocytes selectively release IL-8 in response to in vitro antigen stimulation. They furthermore provide additional support for the concept that as yet to be identified products play a role in atopic pruritus.

Mast cell mediators other than histamine induce pruritus in atopic dermatitis patients: a dermal microdialysis study

“…42 However, no correlation of IL-6 content with itch intensity was found in atopic patients, 43 and IL-2 only induced minor itch sensation in AD patients 44 or controls. 43 Ha Ègermark et al reported chymase-induced itch in humans, 45 but data on pruritic effects of mast cell chymase and tryptase are sparse. 43 Ha Ègermark et al reported chymase-induced itch in humans, 45 but data on pruritic effects of mast cell chymase and tryptase are sparse.…”

Towards profiling the gene expression of fibroblasts from atopic dermatitis patients: human 8K complementary DNA microarray

“…In our experiments using real‐time PCR, we suggested that three candidate genes (IL‐8, TNFAIP6, HAS2) are important in the AD‐fibroblasts, and these three genes showed statistical significance in both type of the patient‐derived samples. Regarding IL‐8, its level was increased in the allergen‐stimulated samples, which suggests a specific release of IL‐8 by the leucocytes in response to in vitro antigen stimulation [17]. Significantly higher IL‐8 concentrations were detected in the severe AD patients rather than in the mild or moderate AD patients [18] and most of the patients with AD showed an up‐regulated IL‐8 protein expression pattern in the eosinophils, but not in the neutrophils [19].…”

Antihistamines in the Treatment of Atopic Dermatitis

“…5 Similarly, opioides and certain proinflammatory cytokines may function in the development of the pruritus of AD. 5,7 Moreover, the role of prostaglandins in evoking pruritus has also been explored. 8 Foods, chemicals, and aeroallergens may also function in the pathogenesis and exacerbation of AD, leading to more itch.…”