Allergen Immunotherapy: Review Article

Abstract

Background: Allergen specific immunotherapy (AIT) is currently the only known causal effective treatment of IgE mediated allergy. AIT was introduced by Leonard Noon more than 100 years ago and currently is the only disease modifying treatment in allergy. The pioneer clinical trials with the AIT were undertaken by Noon in 1911 and continued by Freeman in Europe in grass pollen seasonal allergic rhinitis. The allergens used in the therapy were water-extracts from grass pollen mixtures. Patients selected for immunotherapy must be identified as having an underlying antigenic trigger through a combination of clinical history taking, skin prick tests, and/or allergen specific IgE blood tests. Since its discovery, specific immunotherapy (SIT) has been commonly performed by the subcutaneous route. It is generally accepted that three to five years are needed to achieve a clinical benefit for either sublingual immunotherapy (SLIT) or SCIT and to maintain it after treatment is stopped. A prominent role in SLIT is played by dendritic cells in the oral mucosa, which are of critical importance in inducing tolerance to antigens. The tolerance patterns - that are promoted by dendritic cells and driven by Treg cells - account for the suppressed or reduced activity of inflammatory cells and for the isotypic switch of antibody synthesis from IgE to IgG, and especially to IgG4. The mechanisms promoted by SLIT.