Imidacloprid inhibits IgE-mediated RBL-2H3 cell degranulation and passive cutaneous anaphylaxis

BACKGROUND Imidacloprid has been commonly used as a pesticide for crop protection and acts as nicotinic acetylcholine receptor agonists. Little information about the relationship between imidacloprid and allergy is available. OBJECTIVE This study aims to examine the effects of imidacoprid on IgE-mediated mast cell activation. METHODS The rat basophilic leukemia cell line RBL-2H3 (RBL-2H3 cells) were treated with 10-3 - 10-12 mol/L imidacloprid, followed by measuring the mediator production, influx of Ca2+ in IgE-activated RBL-2H3 cells, and the possible effects of imidacoprid on anti-dinitrophenyl IgE-induced passive cutaneous anaphylaxis (PCA). RESULTS It was shown that imidacoprid suppressed the production of histamine, β-hexosaminidase, leukotriene C4, interleukin-6, tumor necrosis factor-α, and Ca2+ mobilization in IgE-activated RBL-2H3 cells and decreased vascular extravasation in IgE-induced PCA. CONCLUSION It is the first time to show that imidacloprid suppressed the activation of RBL-2H3 cells.