Effect of two nitrogenous diphenyl ether pesticides on mast cell activation

We examined the effect of two nitrogenous diphenyl ether pesticides, nitrofen (NIP) and chlornitrofen (CNP), on mast cell activation. RBL-2H3 (rat basophilic leukemia) cells were exposed to NIP or CNP for 30 min to investigate their effect on degranulation, and for 3 h to investigate their effect on cytokine production and gene expression. NIP and CNP increased IgE receptor-mediated β-hexosaminidase release, MCP-1 release, and TNF-α release in a dose-dependent manner. The increasing effect of CNP on their release was greater than that of NIP. In the gene expression experiment, 30 μg/ml CNP significantly upregulated Egr-1, MCP-1 and GADD45a gene expression. These results suggest that at higher concentrations (more than 30 μg/ml) the nitrogenous diphenyl ether pesticides had both a degranulation-enhancing effect and proinflammatory cytokine-production enhancing effect through the expression of some transcription factors in RBL-2H3 cells.