The aim of this study was to examine the capacity of an in vitro model to test the potential of an allergen to cause cross-linking of IgE bound to the surface of mast cells. The model involved the passive sensitization of murine mast cells, with zearalenone IgE and subsequent exposure to anti IgE, zearalenone, zearalenone-BSA (with up to nine bound zearalenone molecules) or peanut lectin. The extent of cross-linking was determined by measuring the release of IgE mediators TNFalpha and histamine. Release of TNFalpha from IgE sensitized cells increased following exposure to zearalenone-BSA, but not following exposure to zearalenone alone or to peanut lectin. Histamine release could not be quantified against background. The results suggested that the model could be used to test allergenic potential through the availability of epitopes to bind and cross-link IgE on the surface of mast cells. As IgE is species specific, the model was adapted for use with a human cell system employing mast cells in lung fragments. TNFalpha release was measured, and the system was calibrated with the inhalant allergen from Timothy Grass and Timothy Grass specific IgE.