Food-Allergy Disorders
Food-Allergy Disorders
Purpose of review: While much attention is focused upon the role of IgE antibodies in food-allergy disorders, the T cell remains central to all forms, both IgE and non-IgE-mediated, of food-hypersensitivity responses. This review considers the central role of the T cell in this group of disorders and provides a comprehensive overview of recent studies that elucidate our understanding of the mechanisms involved in the pathogenesis of food allergy in regard to the role of the T cell.
Recent findings: Recent studies have defined a dynamic process involving T cell homing receptors (e.g. cutaneous lymphocyte antigen) and activation markers in food-hypersensitivity disorders. Modulation of the T-cell responses occurs through the recognition of dominant allergenic epitopes, the elaboration of regulatory cytokines (e.g. transforming growth factor-
, IL-4, IL-5, tumor necrosis factor-
) and the influence of immunomodulatory microbial and environmental agents. The resulting disorders reflect T-cell dysregulation.
Summary: Significant recent advances in our understanding of the role of the T cell in food hypersensitivity have been made and will probably contribute to improved diagnostic and treatment methods in the near future.
Pioneering work clarifying the mechanisms of oral tolerance in food allergy have firmly established a key role for lymphocytes. The discovery of IgE antibodies in the 1960s confirmed initial hypotheses for a facilitating role of T cells in the production of IgE antibodies through specific cytokine production (IL-4 and IL-13), thus linking 'humoral' allergy with 'cellular' allergy. Current clinical classifications of food-allergy diseases are based mainly on the presence or the absence of food-specific IgE antibodies. IgE-mediated food allergy is by far the most studied type of disease; there is good general knowledge of the mechanisms, reliable diagnostic tools, but no proactive treatment. In non-IgE-mediated food allergy, several lines of evidence implicate lymphocytes in the pathogenesis of the various disorders.
In recent years, three main areas of research in food allergy have emerged. First, mechanisms of oral tolerance in relation to food allergy were extensively studied and have contributed to a better understanding of the disease. Second, research aimed at improving the accuracy of diagnostic tools, and, most recently, at finding predictive tests for the natural history of food allergy, has been partly successful. Third, emphasis has been placed upon finding a proactive treatment for food allergy by exploring several ways in which lymphocytes are implicated.
However, in all of these areas of research, the major drawback has been the difficulty, in human studies, of accessing and studying lymphocytes from gut compartments. Thus, much speculation has had to be made on the basis of the study of circulating lymphocytes, without definite proof of organ-linked mechanisms of sensitization or of relevance to clinical symptoms.
Purpose of review: While much attention is focused upon the role of IgE antibodies in food-allergy disorders, the T cell remains central to all forms, both IgE and non-IgE-mediated, of food-hypersensitivity responses. This review considers the central role of the T cell in this group of disorders and provides a comprehensive overview of recent studies that elucidate our understanding of the mechanisms involved in the pathogenesis of food allergy in regard to the role of the T cell.
Recent findings: Recent studies have defined a dynamic process involving T cell homing receptors (e.g. cutaneous lymphocyte antigen) and activation markers in food-hypersensitivity disorders. Modulation of the T-cell responses occurs through the recognition of dominant allergenic epitopes, the elaboration of regulatory cytokines (e.g. transforming growth factor-
, IL-4, IL-5, tumor necrosis factor-
) and the influence of immunomodulatory microbial and environmental agents. The resulting disorders reflect T-cell dysregulation.
Summary: Significant recent advances in our understanding of the role of the T cell in food hypersensitivity have been made and will probably contribute to improved diagnostic and treatment methods in the near future.
Pioneering work clarifying the mechanisms of oral tolerance in food allergy have firmly established a key role for lymphocytes. The discovery of IgE antibodies in the 1960s confirmed initial hypotheses for a facilitating role of T cells in the production of IgE antibodies through specific cytokine production (IL-4 and IL-13), thus linking 'humoral' allergy with 'cellular' allergy. Current clinical classifications of food-allergy diseases are based mainly on the presence or the absence of food-specific IgE antibodies. IgE-mediated food allergy is by far the most studied type of disease; there is good general knowledge of the mechanisms, reliable diagnostic tools, but no proactive treatment. In non-IgE-mediated food allergy, several lines of evidence implicate lymphocytes in the pathogenesis of the various disorders.
In recent years, three main areas of research in food allergy have emerged. First, mechanisms of oral tolerance in relation to food allergy were extensively studied and have contributed to a better understanding of the disease. Second, research aimed at improving the accuracy of diagnostic tools, and, most recently, at finding predictive tests for the natural history of food allergy, has been partly successful. Third, emphasis has been placed upon finding a proactive treatment for food allergy by exploring several ways in which lymphocytes are implicated.
However, in all of these areas of research, the major drawback has been the difficulty, in human studies, of accessing and studying lymphocytes from gut compartments. Thus, much speculation has had to be made on the basis of the study of circulating lymphocytes, without definite proof of organ-linked mechanisms of sensitization or of relevance to clinical symptoms.
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