The Role of Innate Immune Cells in Allergen Immunotherapy

Purpose of reviewAllergic diseases have become a major health challenge across the world in recent years. Allergen immunotherapy (AIT) is the only disease-modifying therapy that can alter the natural course of allergic diseases. In this review, we aim to introduce the current study on innate immunity in AIT and the association between innate immune cells and the clinical efficacy of AIT briefly.Recent findingsAIT can induce long-term immune tolerance through induction of regulatory T cells, regulatory B cells, and inhibitory cytokines such as IL-10 and TGF-beta, promotion of immunoglobulin class switching, and inhibition of Th2 inflammatory response. Apart from adaptive immune response, innate immune cells have gotten more attention not only in neoplasm and autoimmune disease but also in exploring new treatment in allergic disease. The frequency of type 2 innate lymphoid cell (ILC2) was downregulated, but the function of IL-10-producing ILCs was restored and the number of IL-10-producing ILC2 in patients increased by AIT. The downregulation in function of mast cell, basophil, and granulocyte is also observed after AIT.ILCs, dendritic cells, mast cells, and monocytes play distinct roles in AIT-induced immune tolerance, which are influenced by microenvironment and closely linked with adaptive immunity. With the increasing body of researches shedding light on the role of innate immunity in AIT, the deep mechanisms under AIT create possibilities to find predictive biomarkers which direct clinicians to choose appropriate patients who will benefit from the AIT practically.