الفهرس 
Food AllergyOnly 14 pages are availabe for public view
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Abstract
Background: Food allergy is an adverse health effect arising from a specific immune response that occurs on exposure to a given food or food additive. Food allergies are usually characterized as IgE-mediated, non IgE-mediated (cell-mediated) or mixed immune responses. Food allergy has a significant impact on the quality of life; therefore; timely diagnosis and treatment is imperative. Food additives, especially preservatives, are an entity of food-induced allergic reactions with many postulated theories for the underlying pathophysiology. The most accepted theory is pseudoallergy. Diagnosis involves a careful history and diagnostic tests, including SPTs and serum sIgE level and oral food challenge tests. In case of food additive hypersensitivity, traditional diagnostic tools encounter difficulties such as varying doses of individual additives and difficulty in standardization of the outcome. Therefore, novel cellular tests were introduced such as cellular antigen stimulation test (CAST). In CAST, blood leukocytes are pre-stimulated with the cytokine IL-3 and exposed to allergen(s). Many basophils react by synthesizing sulphidoleukotrienes (sLTs) namely (LTC4, D4 and E4). They are detected by ELISA technique. In this study, the efficacy of CAST in the diagnosis of allergy to food additives was assessed in comparison to other traditional modalities.
Methods: A case-control study conducted on ninety patients recruited from the Allergy and Immunology clinic at Ain Shams University Hospitals. Enrolled patients had allergic symptoms with history suggesting allergy to food additives. Participants were divided into cases and controls groups according to the outcome of OFC test. SPTs, serum sIgE levels, OFC tests (open method) and CAST-ELISA (to sodium benzoate and potassium sorbate) were performed on enrolled patients.
Results: CAST was positive in 58% of cases and 47.5% of the control group. Sensitivity of CAST was 58% and specificity was 52.5%. Sensitivity of quantitative serum sIgE was 92% and specificity was 40%. Sensitivity of SPT was 66% and specificity was 58%.
Conclusion: Cellular Antigen Stimulation test (CAST) has relatively lower sensitivity rate than traditional diagnostic modalities in diagnosis of hypersensitivity to food additives.