Wheat allergy is an allergy to wheat that typically presents as a food allergy, but can also be a contact allergy resulting from occupational exposure. The exact mechanism of this allergy is not yet clear. Wheat allergy may be immunoglobulin E-mediated or not, and may involve a mast cell response. Wheat allergy is rare—its prevalence in adults was estimated to be 0.21% in a 2012 study in Japan. Wheat allergy may be a misnomer. There are many allergenic components in wheat (for example: serine protease inhibitors, glutelins and prolamins), with different responses attributed to different components. Twenty-seven potential wheat allergens have been identified. The allergy, or allergies, are often caused by reactions to the storage proteins present in a wheat seed. While many reactions are caused by wheat proteins, allergenic components are also present in other biochemical forms. The most severe response is wheat-dependent exercise-induced anaphylaxis (WDEIA). WDEIA is attributed to an omega gliadin, which happens to be a relative of the protein that causes celiac disease. Symptoms include nausea, urticaria, and atopy. Gluten sensitivity and Coeliac disease are two different diseases; however, the management is similar. Wheat allergy is a distinct gluten-related disorder with immunological mechanisms, diagnostic criteria, and management strategies that differ from those of celiac disease and non-celiac gluten sensitivity. Management of wheat allergy consists of complete withdrawal of any food containing wheat or other gluten-containing cereals.
Types of allergies Most wheat allergens are proteins, including seed storage proteins, as noted above. There are four major classes of seed storage proteins: albumins, globulins, prolamins and glutenins.
Gluten allergy The relevant prolamins in wheat are gliadins. Gliadins and glutenins form the classic glutens—the causative agents of celiac disease (CD). Distinct immune cells and antibody types differentiate gluten allergy from CD (see Comparative pathophysiology of gluten sensitivities).
Prolamin allergies Prolamins (gliadins) are associated with the more severe form of gluten allergy. Glutenin-induced allergies are often less severe. A proteomics-based study found a γ-gliadin isoform gene.
Glutelin allergies Glutenin (wheat glutelin) is a predominant allergen in wheat. Nine subunits of LMW-glutenin have been found to be in connection with wheat allergies.
Albumin and globulin allergy At present, many of the allergens of wheat have not been characterized; however, the early studies found many to be in the albumin class. A recent study in Europe confirmed the increased presence of allergies to amylase/trypsin inhibitors (serpins) and lipid transfer protein (LPT), but less reactivity to the globulin fraction. The allergies tend to differ between populations (Italian, Japanese, Danish or Swiss), indicating a potential genetic component to these reactivities.
Other allergies
Wheat pollen and grass allergies Respiratory allergies are an occupational disease that develops in food service workers. Previous studies detected 40 allergens from wheat; some cross-reacted with rye proteins and a few cross-reacted with grass pollens. A later study showed that baker's allergy extends over a broad range of cereal grasses (wheat, durum wheat, triticale, cereal rye, barley, rye grass, oats, canary grass, rice, maize, sorghum and Johnson grass), though the greatest similarities were seen between wheat and rye, and that these allergies show cross-reactivity between seed proteins and pollen proteins, including a prominent cross-reactivity between the common environment rye pollen and wheat gluten.
Derivative allergies Proteins are made of a chain of dehydrated amino acids. When enzymes cut proteins into pieces, they add water back to the site at which they cut. This process is called enzymatic hydrolysis, or in the case of proteins it is called proteolysis. The initial products of this hydrolysis are polypeptides, and smaller products are called simply peptides; these are called wheat protein hydrolysates. These hydrolysates can create allergens out of wheat proteins that previously did not exist by the exposure of buried antigenic sites in the proteins. When proteins are cut into polypeptides, buried regions are exposed to the surface, and these buried regions may possibly be antigenic. Such hydrolyzed wheat protein is used as an additive in foods and cosmetics. The peptides are often 1 kD in size (9 amino acid residues in length) and may increase the allergic response. These wheat polypeptides can cause immediate contact urticaria in susceptible people.
Signs and symptoms Wheat allergies are not altogether different from other food allergies or respiratory allergies. However, two conditions, exercise/aspirin induced anaphylaxis and urticaria, occur more frequently with wheat allergies. Common symptoms of a wheat allergy include eczema (atopic dermatitis), hives (urticaria), asthma, "hay fever" (allergic rhinitis), angioedema (tissue swelling due to fluid leakage from blood vessels), abdominal cramps, nausea, and vomiting. Rarer symptoms include anaphylactic shock, anxiety, arthritis, bloated stomach, chest pains, depression or mood swings, diarrhea, dizziness, headache, joint and muscle aches and pains (may be associated with progressive arthritis), palpitations, psoriasis, irritable bowel syndrome (IBS), swollen throat or tongue, tiredness and lethargy, and unexplained cough. In pediatric patients, symptoms related to the digestive system predominate, particularly nausea, vomiting, and diarrhea; and less often - abdominal pain. Skin manifestations such as itching, erythema, urticaria, angioedema, or exacerbation of atopic dermatitis are also common. With age, gastrointestinal symptoms usually disappear and the most common manifestation of WA in older children are skin symptoms. These symptoms may be accompanied by respiratory symptoms such as rhinitis, hoarseness, and chronic cough. These manifestations are much less common in adolescents and adults. Reactions may become more severe with repeated exposure.
Asthma, anaphylaxis, nasal allergies
Exercise-induced anaphylaxis
… excerpt ends here. Continue reading the full article.
