Mouse Anti-Peanut allergen Ara H1 monoclonal antibody, clone Arah1D

Peanuts are one of the more common and important food allergens that can cause severe allergic reactions. Peanuts are highly heat-stable, resistant to acids and enzymolysis, and normal production methods cannot remove the allergenicity of peanut foods. Peanut-induced allergic reactions are immediate hypersensitivity, with the gastrointestinal tract being the most commonly involved target organ, while other target organs include the skin and respiratory system. Clinical manifestations are usually throat edema, abdominal pain, diarrhea, urticaria, asthma, atopic dermatitis, anaphylaxis, and life-threatening in severe cases.

There are more than 10 officially named peanut allergen proteins, of which Ara h 1 is the predominant peanut allergen, binding to serum IgE in 90% of peanut-allergic individuals. It is the most abundant of the peanut allergens, accounting for about 12-16% of the total peanut protein content. Ara h 1 is available in its natural state in mono- and trimeric forms as a soluble protein. The trimeric form is a homotrimeric glycoprotein formed by linking three monomers through hydrophobic interactions, which is highly stable and resistant to gastrointestinal digestion, and heating does not disrupt its allergenicity, resulting in a very stable IgE-binding site and a very strong allergic response. The study of the structure and antigenic determinants of Ara h 1 is key to the study of its sensitization mechanism. The study of the spatial structure of the Ara h1 protein showed that it has a clear secondary fold at the level of secondary structure, of which 31% is α-helical, 36% is β-folded, and 33% is irregularly coiled. Some researchers have found that there are 23 IgE linear binding epitopes on Ara h 1. Substitutions of individual amino acids in the epitopes lead to enhanced or weakened IgE binding ability, and hydrophilic amino acid residues in the epitopes have an important effect on the binding strength of IgE.

Figure 1. Ribbon representations of the structures of Ara h 1
(Source: Palladino C, et al. 2018)

Peanut allergy is a type I allergy, which is an allergic reaction of the body to an allergenic substance. Upon first contact of the allergen with the sensitized body, T and B cells are activated, followed by secretion of specific IgE antibodies by effector B cells. The IgE antibody binds to the FCεRI receptor on the surface of mast cells, a phase known as the induction phase of sensitization. When the allergen re-enters the body, it binds to the IgE on the surface of the mast cell causing the mast cell to degranulate to initiate the pathologic process, a phase known as the effector phase. During this phase the cells release vasoactive substances such as 5-hydroxytryptamine and histamine, which trigger a series of allergic symptoms.