ToxSci Advance Access published online on August 28, 2006
Toxicological Sciences, doi:10.1093/toxsci/kfl094
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1 National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
* To whom correspondence should be addressed. Cytokine profiling of local lymph node responses has been proposed as a simple test to identify chemicals, such as low molecular weight diisocyanates, that pose a significant risk of occupational asthma. Previously, we reported cytokine mRNA profiles for dinitrochlorobenzene (DNCB) and six isocyanates: toluene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), dicyclohexylmethane-4,4'diisocyanate (HMDI), isophorone diisocyanate (IPDI), p-tolyl(mono)isocyanate (TMI), and meta-tetramethylene xylene diisocyanate (TMXDI). The present study was conducted to test the hypothesis that relative differences in the cytokine profile are predictive of relative differences in total serum IgE and respiratory responses to methacholine (Mch) following dermal exposure to the chemicals. After a preliminary experiment to determine an exposure regimen sufficient to achieve responses to Mch following dermal diisocyanate exposure, BALB/c mice received 9 dermal exposures over a period of 28 days to one of six isocyanates, DNCB, or vehicle. Mice were then challenged with increasing doses of Mch and responsiveness was assessed using whole body plethysmography. Serum antibody responses and cytokine mRNA profiles in the draining lymph node were also assessed. In separate experiments, cytokine protein assays were performed after 5 dermal exposures over a 14 day period. The response pattern for IL-4, IL-10, and IL-13 for the different isocyanates was highly reproducible as determined by RNAse protection assay, RT-PCR or cytokine protein levels. However, the relative differences in Th2 cytokine profiles were not predictive of relative differences in either total serum IgE or respiratory responses to Mch following dermal exposure. The data suggest that the cytokine profiling approach needs to be further developed and refined before adoption and that other approaches to hazard identification should be pursued as well. Based on the weight of evidence from all the assays performed, it appears that all 6 isocyanates tested have some potential to cause respiratory hypersensitivity following dermal exposure. Disclaimer: This paper has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency and the Dow Chemical Company and approved for publication. The views expressed in this paper are those of the authors and do not necessarily reflect the views or policies of the institutions represented by the authors, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.
Received July 14, 2006
Accepted August 23, 2006
Immunotoxiocology
Inconsistencies between Cytokine Profiles, Antibody Responses, and Respiratory Hyperresponsiveness Following Dermal Exposure to Isocyanates
MaryJane K. Selgrade 1 *, Elizabeth H. Boykin 1, Najwa Haykal-Coates 1, Michael R. Woolhiser 2, Connie Wiescinski 2, Debora L. Andrews 1, Aimen K. Farraj 1, Donald L. Doerfler 1, and Stephen H. Gavett 1
2 The Dow Chemical Company, Midland, MI 48674
MaryJane K. Selgrade, E-mail: selgrade.maryjane{at}epa.gov
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  A. K. Farraj, E. Boykin, N. Haykal-Coates, S. H. Gavett, D. Doerfler, and M. Selgrade Th2 Cytokines in Skin Draining Lymph Nodes and Serum IgE Do Not Predict Airway Hypersensitivity to Intranasal Isocyanate Exposure in Mice Toxicol. Sci., November 1, 2007; 100(1): 99 - 108. [Abstract] [Full Text] [PDF]
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