Cell-mediated food allergies

These are called delayed hypersensitivity reactions since they normally occur 6-24 hours after exposure. A cell-mediated allergy involves the interaction of food allergens with sensitised lymphocytes, which usually occurs in the gastrointestinal tract. The sensitised lymphocytes produce lymphokines and the generation of cytotoxic T lymphocytes. These latter cells destroy other intestinal cells, including the epithelial cells that are critical for absorption. 

Coeliac disease, which is an allergy to gluten (specifically the gliadin fraction), is a cell-mediated food allergy. 

Symptoms of coeliac disease are diarrhoea, bloating, weight loss, anaemia, bone pain, chronic fatigue, weakness, muscle cramps as well as failure to gain weight and growth retardation in children. 

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Of necessity, anyone working in the food industry has to be aware of food allergies. They involve one of two different immunologic mechanisms. The most common one involves globulins E (IgE). The less common type is the cell-mediated food allergy. 

Food allergy by definition is dependent upon the induction of a specific immune response, and this needs to be of a vigor and quality necessary for the acquisition of sensitization, and the subsequent elicitation of an allergic reaction following encounter with the relevant food protein. Although cell-mediated immune responses are known... 

Bohle B, Zwolfer B, Heratizadeh A, Jahn-Schmid B, Antonia YD, Alter M, Keller W, Zuidmeer L, van Ree R, Werfel T, Ebner C Cooking birch pollen-related food divergent consequences for IgE- and T cell-mediated reactivity in vitro and in vivo. J Allergy Chn Immunol 2006 118 242-249. 

Stabilization of mast cells. Cromolyn prevents IgE-mediated release of mediators, although only after chronic treatment. Moreover, by interfering with the actions of mediator substances on inflammatory cells, it causes a more general inhibition of allergic inflammation. It is applied locally to conjunctiva, nasal mucosa, bronchial tree (inhalation), intestinal mucosa (absorption almost nil with oral intake). Indications prophylaxis of hay fever, allergic asthma, and food allergies. 

The production of antibodies known as IgE and a series of interactions between various cell types and chemical mediators are known to be involved in most confirmed cases of food allergy. This type of IgE-mediated allergy or type I hypersensitivity reaction produces immediate symptoms, the most severe form being anaphylaxis. Other immediate symptoms, such as rhinitis, urticaria, and other affections of the mouth, gut, skin, and respiratory tract, may precede anaphylaxis or occur alone as a less severe manifestation. These reactions would be considered as immediate hypersensitivities. Any food that contains protein has the potential to elicit such allergic sensitization. More than 170 different foods have been documented to be responsible for eliciting immediate hypersensitivities (Taylor, 2000). 

The duality of Thl and Th2 T-helper cells that exists in murine animals probably also exists in humans (14). It has been postulated that IL-4 enhancement promotes the development of IgE-mediated hypersensitivity disorders such as food allergy, while the combination of defective INF-y with enhanced IL-4 production promotes inflammatory atopic disorders such as atopic dermatitis and asthma. IgE irmnunoregulation suggests that the magnitude of the IgE response to persistent allergens depend upon this balance between T-helper cells and their cytokine production. However, environmental and other as yet unidentified factors also contribute to the allergic state of the predisposed individual. 

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