[Sensitization to tea tree oil in Germany and Austria. A multicenter study of the German Contact Dermatitis Group]. / Sensibilisierung auf Teebaumöl in Deutschland und Osterreich--Eine multizentrische Studie der Deutschen Kontaktallergiegruppe.

BACKGROUND AND AIM: Tea tree oil, a distillation product of the Australian tea tree (Melalence alternitolia) is increasingly used as an alternative remedy for various dermatological diseases. Tea tree oil contains several allergenic monoterpenes and sesquiterpenes. In this multicenter study it was evaluated, whether the increasing use of tea tree oil has lead to an increased frequency of sensitization in Germany and Austria which would justify its inclusion into the standard series. PATIENTS AND METHOD: For patch testing a standardized tea tree oil was used, dissolved 5% in diethylphtalate (DEP). Consecutive patients of 11 dermatological departments in Germany and Austria were tested. Readings were taken on day 2 and 3 according to the guidelines of the German Contact Dermatitis Research Group (DKG). RESULTS: 5% tea tree oil was positive in 36/3375 patients (1.1%). Sensitization frequencies showed great regional variations and ranged from 2.3% (Dortmund), 1.7% (Buxtehude), 1.1% (Essen), 0.7% (Graz), to 0% (Berlin, Vienna). 14/36 patients (38.9%) also showed a positive patch test reaction to oil of turpentine. CONCLUSION: Our results show that tea tree oil is an important contact allergen for some centers. It should be tested, if medical history suggests its previous use. Considering the great regional differences in frequencies of sensitization its inclusion into the standard series is not recommended yet.

Role of antigen-induced cytokine release in atopic pruritus.

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 TNFalpha. 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 TNFalpha 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.