Modern ideas about mechanisms of allergen-specific immunotherapy

Reviews of domestic and foreign authors consider different approaches to understanding the formation of immunological and clinical tolerance induced by allergen-specific immunotherapy (ASIT). Despite the wide variety of theoretical research, the mechanism of the bodys immune systems response to ASIT remains unclear. The aim of this review is to analyze the current understanding of the mechanisms of formation of changes in the bodys reactivity in response to an allergen after ASIT. It is known that the type of response to the antigen is determined by its dose. In low-dose ASIT tolerance to the antigen is formed in the absence of inflammation, which is apparently associated with the activation of specific high-affinity receptors on cells of the immune system. High doses of allergen in ASIT probably lead to a rearrangement of cellular receptors, causing a decrease in their number by internalization or a weakening of their sensitivity to an excessive signal (desensitization). Due to a decrease in the number of receptors and / or their loss of sensitivity, the response to the antigen changes according to the principle of negative regulation, implemented at the level of receptor or postreceptor mechanisms. The formation of an anti-inflammatory cytokine response to antigen contributes to the differentiation of naive T cells into inducible regulatory T cells (iTreg). The suppressing effect of Treg on immune system cells affects Th effector cells, mast cells, basophils, eosinophils, B cells, and dendritic cells. The occurring immunological shifts form a new type of tolerant response to the allergen, namely, the change in the type of immunoglobulins from IgE to IgG and IgA and new phenotypes of T memory and B memory cells.