The role of dendritic cells in allergic diseases.

Allergic diseases are important diseases that affect many patients worldwide. Over the past few decades, the incidence of allergic diseases has increased significantly due to social development and increased environmental degradation, which has placed a huge economic burden on public health and even led to an increase in mortality. Substantial progress has been made in the understanding of the mechanisms of allergic diseases, and past studies have shown that the occurrence and development of allergic diseases are closely related to changes in the state of the immune system. With the study and in-depth understanding of innate immune lymphocytes, researchers have gradually discovered that dendritic cells (DC) play an important role in many allergic diseases. DC are the body's main antigen-presenting cells, which ingest, process, and hand allergens, and then secrete chemokines such as chemokine ligands 17(CCL17), CCL22, and upregulate their own surface co-stimulating molecules. Then DC present the antigen peptide to the initial T cells and further differentiate them into helper T cells 2(Th2). As an important part of humoral immunity, Th2 participates in the regulation of type 2 immune response through the secretion of cytokines such as interleukin 4(IL-4), IL-5, and IL-13 and plays a leading role. However, our current research on DC is limited and its status in allergic diseases is unclear.Among them, allergic rhinitis, allergic asthma, atopic dermatitis, and food allergy are DC-mediated Th2 immune-related factor disorder-related allergic diseases, and some progress has been made in recent years in the study of the pathogenesis of these diseases. This paper outlines the common phenotypes and activation pathways of DC in different allergic diseases as well as potential research directions to improve the understanding of its immunomodulatory role in different allergic diseases and ultimately find new ways to treat these diseases.