When an IgE response is generated against an antigen, it qualifies as an allergen. Allergens that induce IgE production and IgE-mediated allergic reactions are defined as complete (e.g., Der p 1, Ara h 2) [24,25]; this contrasts with those not implicated in the sensitization process but are still recognized by IgE (e.g., cross-reactive allergens) [26]. Here, IGHE is linked to allergic disease.