Searching for predictive biomarkers of allergen-specific immunotherapy efficacy based on modern concepts of its mechanisms

Allergen-specific immunotherapy is the primary pathogenetically substantiated method for treating allergic diseases. This treatment decreases the severity of clinical symptoms, has disease-modifying effects, and prevents disease progression, asthma development, and the spread of sensitization. A complex interaction between various cells of innate and adaptive immunity mediates immunological tolerance driven by allergen-specific immunotherapy. Although the primary mechanisms of allergen-specific immunotherapy have been described to date, the understanding of these processes becomes more detailed at the cellular, molecular, and epigenetic levels each year. As a result, deep insights into the mechanisms underlying the development and maintenance of tolerance to allergens during allergen-specific immunotherapy can help reveal the predictive biomarkers of efficacy. These biomarkers can streamline the selection of patients via the identification of responders to allergen-specific immunotherapy. This review presents the current concepts of allergen-specific immunotherapy mechanisms at various stages of the allergic process. Furthermore, the predictive biomarkers of the efficacy are described, with consideration of promising directions of research in this area.