These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: 2,3,7,8-tetrachlorodibenzo-p-dioxin enhances negative selection of T cells in the thymus but allows autoreactive T cells to escape deletion and migrate to the periphery.
    Author: Fisher MT, Nagarkatti M, Nagarkatti PS.
    Journal: Mol Pharmacol; 2005 Jan; 67(1):327-35. PubMed ID: 15492116.
    Abstract:
    Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an environmental pollutant, has been shown to cause thymic atrophy and apoptosis. However, whether TCDD alters the process of T-cell selection in the thymus is not clear. To this end, we investigated the effects of TCDD in the context of the HY-T-cell receptor (TCR) transgenic (Tg) mouse model. We noted that negatively selecting male HY-TCR Tg mice were significantly more sensitive to the thymotoxic effects of TCDD relative to positively selecting female HY-TCR Tg mice, including increased reduction in cellularity and increased induction of apoptosis. TCDD exposure also altered the thymocyte subset composition in HY-TCR Tg male but not female mice. In addition, TCDD treatment resulted in increased extracellularly regulated kinase phosphorylation and lymphocyte-specific protein tyrosine kinase expression in thymocytes of HY-TCR Tg male but not female mice. The increase in proportion of CD8+ mature thymocytes noted in HY-TCR Tg male mice was reflected in the periphery, with TCDD-exposed HY-TCR Tg male mice having increased numbers of CD8+ T cells. Finally, we noted that the proliferative response of HY-TCR Tg male T cells to HY(self)-Ag was enhanced after exposure to TCDD, whereas that of HY-TCR Tg female mice was decreased. Taken together, these data suggest that TCDD alters the process of thymic selection, possibly by enhancing negative thymocyte selection, whereas at the same time allowing autoreactive T cells to escape deletion in the thymus and immigrate to the periphery.
    [Abstract] [Full Text] [Related] [New Search]