IL-31 and IL-33 circulating levels in allergic contact dermatitis.

Enhanced IL-31 expression in skin biopsies is present in allergic contact dermatitis (ACD). IL-33 expression is induced in keratinocytes and in skin of ACD patients. This overexpression is present in both allergic and irritant conditions. The aim of this work was to test the systemic involvement of IL-31 and IL-33 in ACD. IL-31 levels were significantly higher in patients than in controls. IL-33 serum levels, on the contrary, were similar in patients and controls. This work shows a possible systemic involvement of IL-31 and the absence of a systemic involvement of IL-33 in ACD. IL-31 levels do not seem related to the allergen involved, and did not change on the strength of the allergen involved. More likely, IL-31 levels are related to the itch. IL-33, instead, is secreted from damaged or inflamed tissue and might function as an early warning system at the site of skin damage. In the future, IL-31 could be a possible therapeutic target of all pruritic skin diseases resistant to conventional therapies.