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Relevance of Protein Stability in the Allergenicity of Allergenic Food

A food allergy is considered a medical condition, caused by a hypersensitive reaction of the immune system to what would normally be harmless substances present in food. More than 170 foods have been reported to cause allergic reactions and scientists estimate that up to 15 million Americans suffer from some type of food allergy (1). Allergen-specific properties of proteins are essential in generating the immune response, such that a protein’s molecular pattern is directly related to its allergenicity.

What Causes an Allergy?

The signs and symptoms of allergy to some foods are diverse and can include itchiness, vomiting, and diarrhea, among others. Even though there is a long list of foods that have been reported to cause allergies, milk, egg, peanut, crustaceans, fish and wheat are the foods that most commonly contain allergens that cause adverse effects (1). Although food allergies generally develop during childhood, there are some rare cases where people show the first symptoms when they are adults.

An allergen acts as an antigen that triggers an abnormal immune response mediated by Immunoglobulin E (IgE), a type of antibody synthesized by plasma cells. Immunoglobulin E plays a pivotal role in type 1 hypersensitivity. It binds to the antigen and subsequently to Fc receptors present in the membrane of eosinophils, basophils, and mast cells, causing the release of inflammatory compounds such as histamines (2). Histamines are mediators of the itching that can occur with allergies, and they increase the permeability of the capillaries to white blood cells. The release of histamines also increases the contraction of bronchial smooth muscles and the leakage of fluid from blood vessels. This response can sometimes lead to a severe, potentially fatal allergic reaction known as anaphylaxis that can occur within a second or minutes after exposure to the allergen (1).

The Importance of Protein Stability in an Allergic Reaction

Allergens are small proteins that remain stable to changing pH levels and enzymatic degradation. Researchers employ modern protein purification techniques in order to classify IgE-binding and non-IgE-binding structures and to study allergen molecular properties and other conditions, such as solubility and stability. These techniques are also employed to explore which features and behaviors make an allergen unique. The allergenicity of these molecules is related to their solid, three-dimensional molecular structure that protects them from enzymatic cleavage. Therefore, the epitopes that are recognized by IgE remain intact and allergenic during and after digestion (3).

Early Detection of the Disease

To date, the only way to protect against a reaction is by avoiding the food that causes it. Food allergy awareness has increased in the past decade, and more countries are now concerned about expanding the knowledge we have of this disease (5). Early diagnosis is the most effective way to avoid potential anaphylaxis; however, many people discover that they are allergic to some food after they are exposed to the antigen. In severe cases of anaphylaxis, epinephrine is administered. Antihistamines and steroids are also employed as therapies that calm down the immune system cells that generate an allergic reaction (4).

SOURCES:

1- https://www.foodallergy.org/life-with-food-allergies/food-allergy-101/facts-and-statistics

2- Mari A. When does a protein become an allergen? Searching for a dynamic definition based on most advanced technology tools. Clin Exp Allergy. 2008 Jul; 38(7): 1089–1094.

doi:  10.1111/j.1365-2222.2008.03011.x

3- Pekar J, Ret D, Untersmayr E. Stability of allergens. Molecular Immunology.

Volume 100, August 2018, Pages 14-20.

4- Frieri M. Mast Cell Activation Syndrome. Clin Rev Allergy Immunol. (2015) doi:10.1007/s12016-015-8487-6. PMID 25944644

5- Ravid N, Annunziato R, Ambrose M, Chuang K, Mullarkey C, Sicherer SH, Shemesh E, Cox AL (2015). Mental health and quality-of-life concerns related to the burden of food allergy. Psychiatr. Clin. North Am. 38 (1): 77–89. doi:10.1016/j.psc.2014.11.004. PMID 25725570

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Nora Charles is a freelance writer that has worked with many bloggers for several years now.

 

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