Modulation of allergic reactions to apple by pesticide residues

The question whether pesticides can modulate allergy relevant reactions is a controversial issue. In the allergist's office many food-allergic patients believe themselves to react particularly to 'chemically treated' food, especially fruits. Investigations on the influence of pesticides upon apple allergy should bring the problem closer to scientific understanding. Apples of the variety 'Golden Delicious' from 'biologic-dynamic' cultivation and the pesticides chlorpropham and thiram were studied in the experiments. Self-prepared apple protein extracts as well as the pesticides were examined in the in vitro mediator release test from human basophil granulocytes either alone or in combination (spiking experiments). The mediators histamine and leukotriene C-4 were measured by high-performance liquid chromatography (HPLC). The possible binding of chlorpropham to the apple protein was examined using the enzyme allergosorbent test and immunoblotting with chlorpropham spiked apple allergen extracts. Chlorpropham but not thiram acted as a direct histamine liberator. Leukotriene C4 secretion was not induced by any pesticide. In the spiking experiments, when chlorpropham was added to apple extract, it showed a concentration dependent inhibition of histamine release compared to thiram, which had no effect. In an HPLC examination a binding of chlorpropham to apple protein up to 13% could be observed. In the enzyme allergosorbent test chlorpropham caused a reduced specific IgE antibody binding to the apple protein. In the immunoblot there was weakening by chlorpropham of the 18 kDa major allergen band (Mal d I). It is assumed that chlorpropham modulates the apple allergens leading to reduced antibody binding thereby decreasing allergenic potency.