Low-Dose Allergen-Specific Immunotherapy Induces Tolerance in a Murine Model of Shrimp Allergy

The efficacy and safety of allergen-specific immunotherapy (AIT) are highly dose-dependent. Methods: We investigated the dosage effects of AIT and the underlying mechanisms in a murine model of shrimp hypersensitivity. BALB/c mice were sensitized with recombinant shrimp allergen rMet e 1 and challenged orally with a high dose of rMet e 1 to elicit an allergic response. These sensitized mice were then treated with a low (0.01 mg), medium (0.05 mg), or high dosage (0.1 mg) of rMet e 1 intraperitoneally before receiving a second oral challenge. The allergic responses and immunological changes in the gut were compared between animals receiving different dosages. Results: We found that all sensitized mice that received rMet e 1 immunotherapy were desensitized, regardless of the dosage, and protected at the second oral challenge. Nevertheless, the mice in the high-dosage group experienced severe systemic reactions during the treatment phase. In contrast, regulatory T (T_reg) cell-associated genes were upregulated only in the low- and medium-dosage groups, and Foxp3+ cells were more abundant in the gut lymphoid tissues than in the high-dosage group. Conclusions: Our results demonstrate that low-dosage immunotherapy favors the induction of local Foxp3+ T_reg cells and the upregulation of regulatory cytokines. The safety advantages and long-term efficacy of low-dosage immunotherapy should be taken into consideration when developing immunotherapy dose schedules.