Basophils are important for development of allergic skin inflammation

Background Atopic dermatitis skin lesions exhibit increased infiltration by basophils. Basophils produce IL-4, which plays an important role in the pathogenesis of atopic dermatitis. Objective We sought to determine the role of basophils in a mouse model of antigen-driven allergic skin inflammation. Methods Wild-type mice, mice with selective and inducible depletion of basophils, and mice expressing Il4-driven enhanced green fluorescent protein were subjected to epicutaneous sensitization with ovalbumin or saline. Sensitized skin was examined by histology for epidermal thickening. Cells were analyzed for surface markers and intracellular expression of enhanced green fluorescent protein by flow cytometry. Gene expression was evaluated by real-time reverse transcription–quantitative PCR. Results Basophils were important for epidermal hyperplasia, dermal infiltration by CD4+ T cells, mast cells, and eosinophils in ovalbumin-sensitized mouse skin and for the local and systemic TH2 response to epicutaneous sensitization. Moreover, basophils were the major source of IL-4 in epicutaneous-sensitized mouse skin and promote the ability of dendritic cells to drive TH2 polarization of naive T cells. Conclusion Basophils play an important role in the development of allergic skin inflammation induced by cutaneous exposure to antigen in mice.