Food allergies

Adverse reactions to foods are commonly implicated in the causation of ill health. However, foreign antigens, including food proteins and commensal microbes encountered in the gastrointestinal tract, are usually well tolerated. True food allergies, implying immune-mediated adverse responses to food antigens, do exist, however, and are especially common in infants and young children. Allergic reactions to food manifest clinically in a variety of presentations involving the gastrointestinal, cutaneous, and respiratory systems and in generalized reactions such as anaphylaxis. Both IgE-mediated and non-IgE-mediated immune mechanisms are recognized. Important advances in the clinical features underlying specific food hypersensitivity disorders are reviewed.     

Food allergies

Food incompatibilities affect approximately 20% of the general population in Western countries. In about one quarter of the affected children and one tenth of affected adults, the incompatibility is based on an allergy, that is, on an immunologically generated incompatibility reaction. Gastrointestinal symptoms occur in a third of these cases. Food allergies are caused by IgE-dependent or IgE-independent immunologic reactions, which lead to an inflammatory reaction, in which mast cells, eosinophilic granulocytes, and other cells are involved. Both genetic and environmental causes are under consideration. New findings concerning the interaction between the innate immune system and intestinal microflora have generated innovative therapeutic concepts, including the use of probiotics to prevent food allergies. The development of recombinant allergens and varieties of allergens will improve diagnostic possibilities and bring new therapeutic options, such as hyposensitization and induction of immunologic tolerance. Food intolerances (non-immunologic food incompatibilities often caused by specific enzyme deficiencies) must be diagnostically differentiated from food allergies.     

Food allergies and food intolerances

Adverse reactions to foods, aside from those considered toxic, are caused by a particular individual intolerance towards commonly tolerated foods. Intolerance derived from an immunological mechanism is referred to as Food Allergy, the non-immunological form is called Food Intolerance. IgE-mediated food allergy is the most common and dangerous type of adverse food reaction. It is initiated by an impairment of normal Oral Tolerance to food in predisposed individuals (atopic). Food allergy produces respiratory, gastrointestinal, cutaneous and cardiovascular symptoms but often generalized, life-threatening symptoms manifest at a rapid rate-anaphylactic shock. Diagnosis is made using medical history and cutaneous and serological tests but to obtain final confirmation a Double Blind Controlled Food Challenge must be performed. Food intolerances are principally caused by enzymatic defects in the digestive system, as is the case with lactose intolerance, but may also result from pharmacological effects of vasoactive amines present in foods (e.g. Histamine). Prevention and treatment are based on the avoidance of the culprit food.     

Food allergies and eosinophilic gastrointestinal illness

Eosinophilic gastrointestinal disorders are characterized by eosinophilic infiltration and inflammation of the gastrointestinal tract in the absence of previously identified causes of eosinophilia, such as parasitic infections, malignancy, collagen vascular diseases, drug sensitivities, and inflammatory bowel disease. These disorders include eosinophilic esophagitis, eosinophilic gastroenteritis, eosinophilic enteritis, and eosinophilic colitis. This article focuses mainly on eosinophilic esophagitis and eosinophilic gastroenteritis.     

Food allergies and eosinophilic esophagitis--two case studies

Eosinophilic esophagitis (EE) is a clinical-pathological disorder which is being increasingly diagnosed. It is etiologically associated with hypersensitivity to airborne allergens and/or dietary components. However, immediate hypersensitivity to foods has rarely been proven as the etiologic cause of the disorder. Two patients are presented with a history of rhinoconjunctivitis, allergic asthma, atopic dermatitis and food allergies which are currently under control and who show specific IgE to pulses and chicken respectively. These patients developed acute dysphagia and vomiting immediately after ingesting these foods and following appropriate examination were diagnosed as suffering from EE. The study also showed signs of blood hypereosinophilia while the esophageal manometry revealed a motor disorder characterized by aperistalsis and non-propulsive simultaneous waves affecting the lower two-thirds of the organ composed of smooth muscle. Topical treatment with fluticasone propionate was administered over a period of 3 months, in addition to a diet abstaining from the aforementioned foods and this led to remission of dysphagia and normalization of the endoscopic, histological and manometric studies of the esophagus. This situation remained stable for a considerable length of time after steroid treatment was discontinued, which showed that exposure to foods seemed to be the cause of the esophageal disorder. Similarly, allergies to inhalants and other digestive symptoms which appear upon immediate ingestion of the foods involved would not justify the sudden onset of dysphagia. We offer a pathophysiological explanation for the mechanisms of the disease based on the activation of eosinophils and mast cells by IgE and their ability to disturb the dynamic behavior of the neural and muscle components of the esophageal wall.     

Skin allergies

Zum Thema Allergien k?nnen sich am Hautorgan nicht nur mit den unterschiedlichsten Krankheitsbildern manifestieren, auch k?nnen sie durch unterschiedliche allergische Reaktionstypen ausgel?st werden. Der hiermit vorliegende Beitrag beschreibt die pathogenetischen Vorg?nge und die Klassifikation der zu Grunde liegenden allergischen Reaktionen. Zus?tzlich wird die klinische Symptomatik, Diagnostik und Therapie der h?ufigsten allergisch bedingten Hauterkrankungen von der Urtikaria, dem Ekzem, über die Purpura bis zum Arzneimittelekzem dargestellt.     

Ocular allergies

Ocular allergic disease affects not only the conjunctivae but also surrounding structures including the eyelids. Allergic diseases of the eyelid include atopic dermatitis, contact dermatitis, and urticaria/angioedema. They must be differentiated from nonallergic eyelid diseases. Allergic diseases of the conjunctivae comprise a spectrum of disorders from common, non-sight-threatening conditions such as seasonal allergic conjunctivitis, perennial allergic conjunctivitis, and giant papillary conjunctivitis to less common and potentially sight-threatening diseases such as vernal keratoconjunctivitis and atopic keratoconjunctivitis. Each of these conditions is mediated primarily by type I hypersensitivity reactions. The clinical manifestations, differential diagnosis, and treatment of these conditions are reviewed in this article.     

Les allergies alimentaires

The incidence of food allergy appears to be on the increase in industrialized societies. The reasons suggested are consumption of new products and the evolution of food technology. The public perceives food allergies differently from doctors: adverse reactions to foods are misclassified as food allergies although they are in most of the cases non-allergic food intolerance or food aversion. Indeed, in controlled studies, a low prevalence of food allergy although they are in most of the cases non-allergy has been found (1–2% in adults, 2–8% in children). Despite a number of advances in the field of diagnosis and therapy, the standard methods of diagnosis and therapy for food allergies remain the same: double-blind placebo-controlled food challenge and avoidance. Reports on the effects of food processing indicate that certain processes for certain foods can either eliminate, reduce, or not change the allergenic potential. As more food allergen identification and information on the protein structures responsible becomes available, perhaps better ways to use processing methods to reduce or remove allergenicity may become apparent and feasible.     

Current childhood food allergies

Changes of dietary habits, new food technology, international meals and increasing consumption of exotic food has changed the repartition of food allergens. Some food allergens are worrisome and symptoms severe (peanut and nut butters). Others are new and increase strongly: exotic fruits, sesame, mustard and lupin. Primary prevention include avoidance of such food in high risk infants. Product labeling must be improved.     

Occupational allergies to papain

Occupational exposure against dusts of plant, bacterial, mould, and animal enzymes is long known to be associated with a high risk of specific sensitization. The present evaluation of literature data confirms that this is also true for papain. This frequently used industrial protease is derived from papaya (Carica papaya). Several cases of specific airway sensitization caused by papain are verified by a number of case reports and cross sectional studies. As symptoms, results of skin prick tests, detection of specific IgE-antibodies and results of specific bronchoprovocation tests are consistent, an immunologic mechanism can be assumed.     

Occupational allergies to cellulases

In the 1960s an increasing number of occupational allergies in the detergent industry against the proteolytic enzyme Subtilisin were observed. In this context the high sensitization potential of enzyme dusts attracted attention. The present evaluation of literature data confirms that this is also true for cellulases. These enzymes--mostly of fungal origin--are frequently used in biotechnology. Several cases of specific airway sensitization caused by cellulases are verified by a number of studies. As symptoms, results of skin prick tests, detection of specific IgE-antibodies and results of specific bronchoprovocation tests are consistent, an immunologic mechanism seems to be confirmed.     

Occupational allergies to xylanases

The exposure against enzyme dusts have long been known to cause occupational allergies. In the 1960s an increasing number of occupational allergies in the detergent industry were observed. In this context the high sensitization potential of enzyme dusts attracted attention. The present evaluation of literature data confirms that this is also true for xylanases. These frequently used industrial enzymes belong to the hemicellulases and are mostly of fungal origin. Several cases of specific airway sensitization caused by xylanases or other hemicellulases are verified by a number of case reports and cross sectional studies. As symptoms, results of skin prick tests, detection of specific IgE-antibodies and results of specific bronchoprovocation tests are consistent, an immunologic mechanism can be assumed.