A new in vitro model for testing of food allergens: Allergen-specific mediator release of passively sensitized rat basophil leukaemia cells

An assay based on allergen-specific mediator release of Pat basophil leukaemia cells (RBL cells) was investigated as a possible new tool for the in vitro testing of food allergens. The RBL-2H3 cells were sensitized passively with diluted murine pool sera containing IgE specific for food and pollen allergens. These sera were obtained from BALB/c mice after low-dose intraperitoneal injection of birch pollen, celery and peanut extracts. Comparative immunoblotting with murine and human IgE demonstrated that the murine IgE response was directed predominantly against known major allergens. Subsequent to sensitization of the RBL cells with antiserum against birch pollen allergens, apple allergy was used as an immunological model of birch pollen related food hypersensitivities. The known cross-reaction of the major allergens of birch pollen and apple was reproduced completely by the mediator release measured in the murine in vitro assay. The ranking of allergenic potency obtained for these allergens agreed closely with the results of histamine release analyses performed with blood samples of allergic patients. In addition, murine sera against celery tuber were used to study the influence of thermal and non-thermal food processing on the allergenic potency of the food. Again, the results corresponded to previous data obtained in allergic humans and indicated a reduction of potency due to the application of heat, but a high residual biological activity in many mildly processed products. Finally, spurious contaminations of peanut protein in commercial foods could be detected specifically at a concentration of at least 0.01%. This assay is suitable for many applications in food allergen research.