Effect of a single or repeated dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on T cell subpopulations in the Long-Evans rat.
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| Abstract |
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure results in adverse effects on the immune system of experimental animals. The purpose of this study was to compare the effects of a single and repeated dosing of TCDD on splenic T-cell subpopulations in Long Evans rats 9 days post-exposure to TCDD. A single dose (25 microg/kg body weight) of TCDD resulted in reduced body weight. The percentage and total number of CD4+ or CD8+ subsets and percentage of CD4+ or CD8+ cell cycling in the S and G2M phases were similar in the single dosed (25 microg/kg body weight) TCDD group compared with the vehicle control. A repeated dose (5 microg/kg/day for 5 days) of TCDD also resulted in a significant reduction in body weight. However, multiple doses of TCDD significantly decreased the percentage of the CD4+ subset and the percentage of CD4+ cells cycling in the S and G2M phases. No significant change occurred in the CD8+ cell subpopulation after single or multiple dosing with TCDD. These results demonstrated that repeated dosing of TCDD decreased the total percentage of CD4+ cells and the percentage of CD4+ cells cycling 9 days post-exposure, while an analogous single dose of TCDD failed to affect the CD4+ cell subpopulation. The difference in biological responses to a single versus 'equivalent' multiple (cumulative) dose of TCDD is discussed.
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| Authors | W Huang, L D Koller |
| Journal | Toxicology letters (Toxicol Lett) Vol. 109 Issue 1-2 Pg. 97-104 (Sep 20 1999) ISSN: 0378-4274 [Print] Netherlands |
| PMID | 10514035 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.) |
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