Serum IL-31 levels are increased in a subset of patients with mastocytosis and correlate with disease severity in adult patients

In recent years, it has become evident that the novel cytokine IL-31 plays an important role in the induction of chronic skin inflammation.5,6 Patients with atopic dermatitis, chronic spontaneous urticaria, allergic contact dermatitis, prurigo nodularis, and primary cutaneous lymphomas express increased serum IL-31 and IL31 mRNA levels in the skin.6,7 IL-31 serum levels in patients with atopic dermatitis also correlate with disease activity7 and levels of TH2 cytokines, such as IL-4 and IL-13. [...]gene variants of IL31 are associated with the development of atopic dermatitis. Surprisingly, when we compared the group of 12 pediatric patients, who all had CM, with the group of 28 adult patients with CM or ISM, we observed significantly increased IL-31 levels in pediatric patients (P = .0279; Fig 1, A). Because pediatric patients typically show lower tryptase levels than adult patients, which was also confirmed in our study (see Fig E1, A), this finding was unexpected.