Scientific Study

Allergic diseases; including asthma and food allergies; are an increasing health concern. Immunotherapy is an effective therapeutic approach for many allergic diseases but requires long dose escalation periods and has a high risk of adverse reactions; particularly in food allergy. New methods to safely induce Ag-specific tolerance could improve the clinical approach to allergic disease. We hypothesized that Ag-specific tolerance induced by the i.v. injection of Ags attached to the surface of syngeneic splenic leukocytes (Ag-coupled splenocytes [Ag-SPs]) with the chemical cross-linking agent ethylene-carbodiimide; which effectively modulate Th1/Th17 diseases; may also safely and efficiently induce tolerance in Th2-mediated mouse models of allergic asthma and food allergy. Mice were tolerized with Ag-SP before or after initiation of OVA/alum-induced allergic airway inflammation or peanut-induced food allergy. The effects on disease pathology and Th2-directed cytokine and Ab responses were studied. Ag-SP tolerance prevented disease development in both models and safely tolerized T cell responses in an Ag-specific manner in presensitized animals. Prophylactically; Ag-SP efficiently decreased local and systemic Th2 responses; eosinophilia; and Ag-specific IgE. Interestingly; Ag-SP induced Th2 tolerance was found to be partially dependent on the function of CD25(+) regulatory T cells in the food allergy model; but was regulatory T cell independent in the model of allergic airway inflammation. We demonstrate that Ag-SP tolerance can be rapidly; safely; and efficiently induced in murine models of allergic disease; highlighting a potential new Ag-specific tolerance immunotherapy for Th2-associated allergic diseases.