Immunotherapy and allergic asthma: Critical analysis of the immunological mechanisms behind tolerance induction

Asthma associates with bronchial hyperresponsiveness, bronchoconstriction, and chronic inflammation mediated by the structural and inflammatory cells present or recruited into the bronchial mucosa. Allergic asthma develops in childhood on a genetically predisposed most often through sensitization to an aeroallergen which should be considered harmless by the immune system but which, in these patients, leads to a response major called immediate hypersensitivity mediated by IgE. Allergen immunotherapy is currently the only treatment to reverse the course of disease by inducing immune tolerance to the allergen evidenced by the regression of clinical signs of allergy. Allergen immunotherapy's protocols are based on exposure to increasing doses of allergen. Both routes are used to this day. The efficacy is based on the induction of B lymphocyte populations and regulatory T, producing immunosuppressive cytoldnes. The production of specific IgE allergen gives way to that of IgG4 type of blocking antibodies of the same antigenic specificity. Finally allergen immunotherapy decreases the activation and recruitment of effector cells of inflammation in tissues exposed to the allergen. The sublingual route also allows to benefit from the constitutive tolerogenicity of the mucosal immune system. (C) 2015 Elsevier Maison SAS. All rights reserved.