Immunologic characterization of 3 murine regimens of allergen-specific immunotherapy

Background: Allergen-specific immunotherapy (ASIT) is used to treat the symptoms of immediate type I hypersensitivity. The mechanisms driving establishment of allergen tolerance are not yet fully understood. Objective: The goal of this study was to develop and immunologically characterize 3 murine models of ASIT to simulate protocols currently used to treat patients with type I hypersensitivities. Methods: Ovalbumin (OVA)-sensitized mice were desensitized to OVA by means of repeated injections of OVA with a rapid, intermediate, or gradual protocol. After desensitization, mice were assessed for clinical sensitivity to OVA, and immunologic parameters were assessed. Results: Mice in all treatment protocols displayed decreased vascular permeability in response to OVA challenge after desensitization. Circulating OVA-specific IgE levels, as well as basophil activation in response to OVA stimulation and IgE cross-linking, were significantly decreased in all treatment groups. Intermediate and gradual protocols, but not rapid desensitization, suppressed splenocyte proliferation and production of IL-4, IL-5, and IFN-gamma in response to OVA and polyclonal activation. Similarly, significant increases in IL-10 production, numbers of CD4(+) CD25(+) forkhead box protein 3-positive regulatory T cells, andOVA-specific IgG1 antibody levels were only observed in mice undergoing prolonged ASIT regimens. Conclusion: Suppression of IgE-mediated activation is a common feature of all desensitization schedules. Induction of immunoregulatory networks requires prolonged desensitization schedules.