Ara h 1, Ara h 2, and Ara h 3 (major peanut protein allergens) (Ara h 1, Ara h 2, Ara h 3)

Ara h 1, Ara h 2, and Ara h 3 are the primary protein allergens in peanuts and represent the main elicitors of IgE-mediated allergic reactions in sensitized individuals. They are seed storage proteins involved in providing amino acids for seed germination, but when ingested by allergic individuals, they trigger immune responses ranging from mild symptoms to life-threatening anaphylaxis. Ara h 1 (a 7S vicilin globulin) and Ara h 3 (an 11S legumin/glycinin) are both part of the cupin superfamily, while Ara h 2 is a conglutin belonging to the 2S albumin family. These proteins are highly stable, resistant to digestion, and contribute substantially (over 30%) to peanut protein content. Measurement of specific IgE to these components is used clinically to diagnose peanut allergy and estimate reaction risk severity. Currently, the peanut allergen powder Palforzia is approved for oral immunotherapy targeting these allergens, seeking to desensitize patients and reduce risk upon accidental exposure. However, the potential for severe reactions remains a central safety concern for all therapies and diagnostics involving these allergens. Cross-reactivity has also been observed with storage proteins from other legumes and nuts, complicating the clinical picture.

Other names

Vicilin7S globulin2S albuminconglutinGlycinin11S globulinlegumin

Provocation of IgE-mediated activation of mast cells and basophils, leading to degranulation and release of allergic mediators. Immunotherapy (oral desensitization) to gradually increase tolerance (Palforzia).