Chemical Immunology and Allergy

About 17% of German children and adolescents suffer from at least one of the following atopic illnesses: allergic rhinoconjunctivitis, atopic eczema or asthma. Consistent professional therapy is necessary to limit the health-related risks and improve these medical conditions. The consequences of a diagnosis often mean an additional task for the parents of diseased children, where they have to act simultaneously as an educator and therapist for their children. Structured educational programmes were developed for a few diseases such as asthma and atopic eczema in order to prepare parents and affected children to accept this important responsibility...

Despite a trend towards delayed weaning, food allergies (FAs) have increased in the past few decades and are now considered a public health concern, resulting in significant morbidity as well as occasional mortality. Whilst genetic factors are clearly important in the development of FA, a rise in FAs has occurred over a short period of time and is therefore unlikely to be due to germ-line genetic changes alone. Thus, it seems plausible that one or more environmental exposures may, via epigenetic changes, result in the interruption of the 'default immunologic state' of tolerance to foods...

The majority of research on food allergy has been bio-medical in orientation, focusing on issues such as the molecular structure of allergens, or aimed at methods of diagnosis. In the last decade, there has been a growing interest in the development of questionnaires that measure the impact of food allergy on health-related quality of life (HRQL). These studies have provided insight into the everyday burden of living with food allergy and have suggested ways that HRQL can be improved. The EuroPrevall project (europrevall@bbsrc...

The labeling of allergenic foods is an important public health measure to assist food-allergic consumers in avoiding foods that can cause allergic reactions. The regulatory framework for such labeling depends upon the selection of priority allergenic foods, which vary among countries. Most countries include milk, eggs, fish, crustacean shellfish, peanuts, tree nuts, soybeans, and cereal sources of gluten on the priority allergenic foods list, as recommended by the Codex Alimentarius Commission. However, a variety of other foods appear on the priority lists of some countries but not on others...

Given its increasing prevalence and potential severity, food allergy not only negatively impacts the health and quality of life of affected individuals but also carries a significant economic burden. To address these problems, a community approach including efforts to increase awareness of food allergy among the general public and the implementation of appropriate public policies to keep affected individuals safe is required. This chapter reviews the general public's knowledge and perceptions of food allergy, the disease's psychosocial impact on affected individuals, and the current state and future directions of food allergy public policy...

Dietary intervention is a crucial component of food allergy management but can negatively impact nutrient intake. A comprehensive nutrition assessment with appropriate intervention is warranted in all children with food allergies to meet nutrient needs and optimize growth. Nutrition assessment may also be indicated in adults with food allergy. Frequently, an elimination diet is absolutely necessary to prevent potentially life-threatening anaphylaxis. Allergen elimination can also improve chronic symptoms, such as atopic dermatitis, when a food is proven to trigger symptoms...

Eosinophilic oesophagitis (EoE) is an antigen-driven pan-oesophagitis that is defined by the presence of at least 15 eosinophils per high power field on oesophageal histology in conjunction with upper gastrointestinal symptoms. EoE is closely associated with atopic disorders, in particular with food allergy, and as for other atopic diseases in childhood, there is a strong preponderance of male patients who have this disorder. The mechanisms leading to EoE have been characterised at the molecular level. Eotaxin-3, interleukin-5 and interleukin-13 are the key effector molecules in EoE pathogenesis...

Food allergy is a known trigger of anaphylaxis. Although the awareness of food allergies has improved, food-related allergic reactions and anaphylaxis still commonly occur. The recognition of anaphylaxis, its prompt treatment, and patient education are important for the prevention of future food reactions. Patients and health care providers should also recognize the importance of epinephrine as the primary treatment of anaphylaxis. When food-related anaphylaxis occurs, patients should receive education regarding their food allergies, an epinephrine auto-injector, and follow-up with a food allergy specialist to reduce the risk of future food-related reactions...

Approximately one-third of children with severe atopic eczema suffer from a food allergy, whereas in adult patients, food allergies are rare. In child patients, three different clinical reaction patterns can be differentiated as follows: (1) immediate-type reactions, (2) isolated late eczematous reactions, and (3) combined immediate-type and late eczematous reactions. In childhood food allergies, food allergens, such as cow's milk or hen's egg, are primarily responsible for allergic reactions, while in adolescents and adults, food allergies often develop consecutively after primary sensitization to pollen allergens...

Gastrointestinal food allergies present during early childhood with a diverse range of symptoms. Cow's milk, soy and wheat are the three most common gastrointestinal food allergens. Several clinical syndromes have been described, including food protein-induced enteropathy, proctocolitis and enterocolitis. In contrast with immediate, IgE-mediated food allergies, the onset of gastrointestinal symptoms is delayed for at least 1-2 hours after ingestion in non-IgE-mediated allergic disorders. The pathophysiology of these non-IgE-mediated allergic disorders is poorly understood, and useful in vitro markers are lacking...

Fruit and vegetable allergies are the most prevalent food allergies in adolescents and adults. The identification of the allergens involved and the elucidation of their intrinsic properties and cross-reactivity patterns has helped in the understanding of the mechanisms of sensitisation and how the allergen profiles determine the different phenotypes. The most frequent yet contrasting fruit and vegetable allergies are pollen-food syndrome (PFS) and lipid transfer protein (LTP) syndrome. In PFS, fruit and vegetable allergies result from a primary sensitisation to labile pollen allergens, such as Bet v 1 or profilin, and the resulting phenotype is mainly mild, consisting of local oropharyngeal reactions...

Fish and shellfish consumption has increased worldwide, and there are increasing reports of adverse reactions to fish and shellfish, with an approximate prevalence of 0.5-5%. Fish allergy often develops early in life, whilst shellfish allergy tends to develop later, from adolescence onwards. Little is known about the natural history of these allergies, but both are thought to be persistent. The clinical manifestations of shellfish allergy, in particular, may vary from local to life-threatening 'anaphylactic' reactions within an individual and between individuals...

Among grains and legumes, wheat and soybean are the most frequent and well-characterized allergenic foods. Wheat proteins are divided into water/salt-soluble and water/salt-insoluble (gluten) fractions. The most dominant allergen in the former is α-amylase/trypsin inhibitor, which acts as an inhaled allergen causing baker's asthma. Gluten allergens, including ω-5 gliadin and high- and low-molecular-weight glutenins, contribute to wheat-dependent exercise-induced anaphylaxis in adults and immediate-type wheat allergies, including anaphylaxis, in children...

Allergy to peanut and tree nuts is a major worldwide health concern. The prevalence of these allergies may be increasing, but the reasons for these increases remain unclear. This group of foods accounts for a large proportion of severe and fatal food-allergic reactions. These allergies present most often during childhood but can occur at any age. Resolution is possible but uncommon, and frequent lifetime reactions caused by accidental ingestion are a serious problem. The major allergens of peanut and most tree nuts have been identified, allowing for insights into patient diagnoses, clinical outcomes, and potential future immunotherapies...

Egg allergy is one of the most frequent food allergies in infants and young children. The prevalence of egg allergy is estimated to be between 1.8 and 2% in children younger than 5 years of age. The reactions are mainly mediated by IgE and partially by non-IgE or are a mix of both types. Egg white contains more than 20 different proteins and glycoproteins. Ovomucoid (Gal d 1), ovalbumin (Gal d 2), conalbumin (ovotransferrin) (Gal d 3) and lysozyme (Gal d 4) have been identified as major allergens in hen's egg...

Cow's milk allergy is among the more frequent food allergies in infants and children. Because its suspicion stems from a plethora of symptoms, it is frequently reported. However, the development of a rigorous diagnostic pathway will reduce the diagnosed children to less than 50% of those reported. Cow's milk allergy is the only specific food allergy for which an EBM guideline exists. According to the guidelines (Diagnosis and Rationale for Action against Cow's Milk Allergy), a diagnostic process based on the pre-test probability of this condition is available...

The standardized therapeutic approach for food allergy is based on avoidance of allergens in foods. Oral immunotherapy (OIT) is a significant focus of food allergy research and appears to be effective in inducing desensitization. However, most patients receiving OIT have mild to moderate symptoms during the therapy, and it has not been clearly established whether OIT is effective in inducing permanent tolerance. Recently, novel therapeutic approaches for food allergy, or sublingual immunotherapy and epicutaneous immunotherapy using an anti-IgE monoclonal antibody (omalizumab), have been examined in some studies...

There is currently no well-established disease-modifying treatment for food allergy, so management relies upon strict avoidance of food allergen(s), implementation of risk minimisation strategies to avoid inadvertent exposure and allergic reactions, and prompt management of acute allergic reactions, should they occur. The pharmacological management of acute food-induced allergic reactions is dependent on the underlying pathophysiology of the allergic reaction and the severity of clinical symptoms and signs...

Accurately diagnosing patients with suspected food allergy is obviously critically important. The patient's health may be compromised if problem foods are left in the diet, while nutrition and quality of life may be negatively affected if foods are unnecessarily removed from the diet. In some patients, the diagnosis is very straightforward, such as with anaphylaxis with the first known exposure to peanut, but in many cases, the diagnosis will not be clear based on the history, skin tests, and serologic tests, especially because these tests often yield falsely positive results...

Although most food allergy patients have immediate-type reactions, some have delayed-type reactions. Unlike for the detection of food-specific IgE antibody in immediate-type (IgE-mediated) food allergies, only a few tests are currently available to aid in the diagnosis of delayed-type (non-IgE-mediated) food allergies. This chapter summarizes our current understanding of one in vitro test and one in vivo test for non-IgE-mediated food allergies: the lymphocyte stimulation test (LST) and the atopy patch test (APT)...