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Fig. 1 | World Allergy Organization Journal

Fig. 1

From: The impact of allergen exposure and specific immunotherapy on circulating blood cells in allergic rhinitis

Fig. 1

How circulating blood cells participate in allergic rhinitis (AR). Allergen exposure initiates a local inflammatory response involving recruitment of circulating blood cells to the nasal mucosa. In the early phase, neutrophils are mobilized as first-line responders of the innate immune system and contribute to epithelial and nerve damage via cytotoxic mediator release. Damaged epithelial cells release DAMPs and cytokines (e.g. TSLP, IL-25, IL-33) recruiting circulating lymphocyte subtypes (e.g. ILC2), which accumulate in the nasal mucosa and promote the Th2 inflammatory response. In the late phase, mediator release from recruited eosinophils and basophils further contributes to AR symptoms via epithelial damage and microvascular leaking. Blood-derived monocytes participate in promotion and resolution of the allergic response by differentiation into DCs and tissue macrophages. Boxes below the cartoon illustrate different blood cells and their reported changes after allergen exposure. DC, dendritic cell; ECP, eosinophil cationic protein; ILC, Innate Lymphoid Cell; MBP, major basic protein; MMP, matrix metalloprotease; NET, neutrophil extracellular trap; RBC, red blood cell; ROS, reactive oxygen species; for simplicity, IgE-mediated mechanisms are not illustrated

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