Methods: We identified a novel peptide from the major peanut allergen Ara h 1 that is recognized by C57Bl/6 mice. Mice were sensitized to peanut epicutaneously and treated 1 week later with 2 intraperitoneal injections of peptide, 1 week apart. We included 6 doses, ranging from 0.01 ug to 300 ug of peptide. Mice were subsequently challenged with whole peanut extract and evaluated for signs of anaphylaxis. They were monitored over a period of 40 minutes for clinical signs of allergic reaction, changes in rectal temperature, and vascular leakage.
Results: Peptide immunotherapy provided significant protection against anaphylaxis in a dose-dependent manner. Mice that received 100 ug of Ara h 1 peptide exhibited the highest level of protection. Control mice treated with saline experienced a mean maximum temperature drop of 7.4°C, while mice receiving 100 ug of peptide experienced a drop of 2.0°C (p=0.01 vs control). Maximum mean clinical score was 4.0 in control mice, and 1.8 in treated mice (p=0.002). Mean hematocrit for control mice was 56.4%, and 48.9% for treated mice (p=0.16).
Conclusions: One T cell epitope-containing peptide from a single major peanut allergen can protect against anaphylaxis elicited by whole peanut extract challenge. Studies of peptide immunotherapy in clinical peanut allergy are warranted.