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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effect of homozygous lpr and gld mutations on the immune functions and induction of autoimmunity

Hammond-McKibben, Denise M. 06 June 2008 (has links)
The murine <i>lpr</i> gene encodes for an aberrant form of Fas (CD95), a molecule involved in apoptosis. The mouse <i>gld</i> gene leads to the expression of a defective Fasligand. Mice homozygous for <i>lpr</i> or <i>gld</i> mutations develop severe lymphoproliferative and autoimmune disease characterized by the accumulation of unique CD4⁻CD8⁻ (double-negative, DN) T cells. Because of these poor functions in vitro, the nature and significance of DN T cells in the autoimmune disease process is not clear. In the current study we found that <i>lpr</i> DN T cells could mediate spontaneous lysis of certain tumor cells as well as mediate redirected lysis of various tumor targets when stimulated through the CD3/αβTCR complex and certain adhesion molecules, such as, CD44 and gp90<sup>MEL-14</sup>. The DN T cells constitutively transcribed perform, TNF-α and IFN-γ genes. Unlike the DN T cells from <i>lpr</i> mice, similar cells from <i>gld</i> mice failed to exhibit spontaneous cytotoxicity despite expression of similar levels of cytokines and adhesion molecules. Furthermore, lpr DN T cells could mediate redirected lysis of Fas⁺ but not Fas⁻ target cells. Together, these studies suggested that lysis of target cells by DN T cells was dependent on the interaction between Fas and Fas-ligand. The fact that <i>lpr</i> DN T cells can be activated via CD44 and gp-90<sup>MEL-14</sup> suggested that these T cells may be able to mediate lysis of endothelial cells which bear the ligand for these adhesion molecules. Further studies revealed that the <i>lpr</i> DN T cells could mediate spontaneous lysis of endothelial cells and that CD44-hyaluronate interactions were important for endothelial cell lysis. Thus, interactions between DN T cells and endothelial cells <i>in vivo</i> may trigger an inflammatory response and contribute to the vasculitis seen in <i>lpr</i> and <i>gld</i> mice. We also addressed the hypothesis that acquired immunodeficiency syndrome (AIDS) may be a consequence of destabilization of the idiotypic network. These studies demonstrated that auto- or allo-immunizations involving recognition of class II MHC antigens can trigger an anti-HIV response and such possibilities should be taken into consideration while delineating the pathogenesis of AIDS. / Ph. D.

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