Mohamed H. Shamji, Janice A. Layhadi, Hanisah Sharif, Martin Penagos, Stephen R. Durham
J Allergy Clin Immunol Pract. 2021 Mar 27:S2213-2198(21)00363-9. doi: 10.1016/j.jaip.2021.03.029.
Patients with IgE-mediated rhinoconjunctivitis and/or bronchial asthma who do not respond to symptomatic treatment or have severe side effects are often recommended allergen immunotherapy. Prolonged treatment has shown long-term benefits in patients with moderate to severe allergic rhinitis. The long-term efficacy from allergen immunotherapy represents a decrease in IgE activation of mast cells and tissue eosinophilia, which is accompanied by early induction of regulatory T cells, immune deviation in favor of TH1 responses, and induction of local and systemic IgG and IgA antibodies. These antibodies, whose primary function is to be protective, can prevent the formation of allergen-IgE complex and subsequent activation of the mast cells and TH2 facilitated by IgE.
Some studies demonstrate the importance of innate responses mediated by type 2 dendritic cells and innate lymphoid cells in allergic inflammation. Type 2 dendritic cells and lymphoid cells are regulated by cytokines derived from the respiratory epithelium. New subsets of regulatory cells induced by immunotherapy include:
- IL-35-producing regulatory T cells,
- Regulatory B cells,
- A subset of T follicular regulatory cells, and
- IL-10-producing group 2 innate lymphoid cells.
These regulatory cells may represent biomarkers that will predict the clinical response to immunotherapy and evaluate the efficacy, safety, and long-term tolerance.
More studies are required to identify candidate biomarkers as a routine immune-monitoring tool for assessing allergen immunotherapy response.