Toxicological Sciences, Vol 52, 50-60, Copyright © 1999 by Society of Toxicology
BP Lawrence, M Meyer, DJ Reed and NI Kerkvliet
Recent developments in basic immunology have revealed the importance of
glutathione (GSH) and cellular redox balance in the generation of an immune
response. In the liver, it has been shown that exposure to
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters cellular GSH and reactive
oxygen intermediate (ROI) production. We have tested the hypothesis that
TCDD mediates the suppression of the cytotoxic T lymphocyte (CTL) response
to alloantigen by increasing oxidative stress. Total cellular GSH, GSSG,
and GSH-protein adducts were analyzed by HPLC. Changes in intracellular GSH
and ROI were simultaneously measured in isolated hepatocytes and individual
subpopulations of spleen cells (CD4+, CD8+, B220+, and Mac-1+) following in
vivo exposure to TCDD and antigenic challenge with P815 mastocytoma cells.
Monochlorobimane was utilized to measure GSH levels, and two fluorescent
probes were used to evaluate ROI levels: dichlorofluoroscein diacetate to
monitor peroxides and dihydroethidine to assess superoxide anion. In
hepatocytes, in vivo treatment with TCDD resulted in a transient, 2-fold
increase in GSH, a 50% decrease in peroxide levels and a small (20-40%)
decrease in superoxide anion levels. Although alloantigen challenge
resulted in increased GSH and peroxide in spleen cells, in vivo exposure to
TCDD had no effect on splenic ROI levels, nor did it consistently alter GSH
levels in any subpopulation of spleen cells examined. Moreover, in vivo
treatment with the antioxidant N-acetyl cysteine failed to affect the
immune suppression caused by TCDD. These results suggest to us that
although TCDD perturbs cellular redox balance in the liver, it does not
exacerbate or diminish the normal increased GSH and ROI which occur in the
spleen in response to antigenic challenge.
ARTICLES
Role of glutathione and reactive oxygen intermediates in 2,3,7,8- tetrachlorodibenzo-p-dioxin-induced immune suppression in C57Bl/6 mice
Department of Environmental and Molecular Toxicology, Environmental Health Sciences Center, Oregon State University, Corvallis, USA.
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