Allergen immunotherapy (AIT) is the only curative treatment for allergic disorders now accessible, and it has been used in clinical practice for over a century. To maintain homeostasis and prevent chronic inflammation, immunological tolerance to nonhazardous environmental and self-antigens must be instilled and maintained. Regulatory B (BREG) cells are immunoregulatory cells that protect against chronic inflammatory reactions by producing anti-inflammatory cytokines such as IL-10, TGF-, and IL-35. The relevance of BREG cells in the setting of autoimmune disorders has been thoroughly shown. Data demonstrating their function in allergic response control is steadily accumulating. This review highlights current discoveries about BREG cells and their possible role in AIT. BREG cells promote AIT in allergic airway inflammation and intestinal inflammation models by inducing regulatory T (TREG) cells. During venom immunotherapy, the number of BREG cells in people rises, but the phenotype of allergen-specific B cells alters. IL-10-mediated suppression of effector T cells, including TH2 responses, TREG cell induction, IL-10-mediated inhibition of Dendritic cell maturation, modulation of T follicular helper responses, and production of anti-inflammatory IgG4 antibodies are all mechanisms of BREG-mediated tolerance to allergens.

Evidence suggests that BREG cells may play a role in the induction and maintenance of allergen tolerance during AIT. A greater knowledge of the involvement of B cells and BREG cells in AIT might lead to the development of tailored treatments aimed particularly at boosting BREG responses during AIT.