Interleukin 13-positive mast cells are increased in immunoglobulin G4-related sialadenitis.

Interleukin (IL)-13 is a T helper 2 (Th2) cytokine that plays important roles in the pathogenesis of asthma. IL-13 induces hypersensitivity of the airways, increased mucous production, elevated serum immunoglobulin (Ig) E levels, and increased numbers of eosinophils. Many patients with IgG4-related disease have allergic backgrounds and show elevated serum IgE levels and an increase in the number of eosinophils. Upregulation of Th2/regulatory T (Treg) cytokines, including IL-13, has been detected in affected tissues of patients with IgG4-related disease. We previously reported that mast cells might be responsible for the production of the Th2/Treg cytokines IL-4, IL-10, and transforming growth factor (TGF)-β1 in IgG4-related disease. In this study, immunohistochemical analysis showed increased numbers of IL-13-positive mast cells in IgG4-related disease, which suggests that mast cells also produce IL-13 and contribute to elevation of serum IgE levels and eosinophil infiltration in IgG4-related disease.