Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Toxicology." Includes bibliographical references (p. 158-173).

The activation and effector function of CD4+ T cells are critical points of regulation during an antigen specific T cell response. Dysregulation of these processes can lead to the development of human diseases, encompassing both immunodeficiency and autoimmunity. Members of the TNF superfamily have recently emerged as important regulators of T cell responses, with their overexpression causing autoimmune inflammation in animal models. As overproduction of the novel TNF superfamily ligand BAFF is associated with several autoimmune conditions, we sought to examine the potential role of BAFF as a regulator of T cell activation and effector function. We initially demonstrated BAFF costimulation of T cell activation in vitro. Generation of specific monoclonal antibodies identified BAFF-R as the only BAFF receptor present on T cells, and showed that it was expressed in an activation-dependent and subset-specific manner. Impaired BAFF costimulation in BAFF-R deficient mice indicated that BAFF-R was crucial for mediating BAFF effects in T cells. Analysis of T cell responses in vivo revealed that BAFF transgenic mice have increased T cell priming and recall responses to protein antigens, and showed a corresponding increase in the DTH model of Th1 cell-dependent inflammation. In addition, Th2-dependent allergic airway responses are suppressed in BAFF transgenic mice. Crossing to a B cell deficient background revealed that the proinflammatory effects of BAFF on T cell priming and DTH rely on the presence of B cells, while the suppressive effects during allergic airway inflammation are B cell independent. These data demonstrated that BAFF regulated the outcome of T cell responses in vivo and identified BAFF dependent crosstalk between T and B cells. Stimulation of B cells with BAFF induced the upregulation of MHC class II and ICOS-L both in vitro and in vivo. Induction of these cell surface molecules was associated with an increased capacity to induce T cell proliferation, however this effect was independent of ICOS-L expression. Thus it was demonstrated that BAFF regulated T cell activation and effector function both directly, via stimulation of BAFF-R, and indirectly, by altering the function of B cells. These data suggest that BAFF dependent alterations in T cell function may be an additional causative factor in the association between elevated BAFF levels and the generation of autoimmunity.

The activation and effector function of CD4+ T cells are critical points of regulation during an antigen specific T cell response. Dysregulation of these processes can lead to the development of human diseases, encompassing both immunodeficiency and autoimmunity. Members of the TNF superfamily have recently emerged as important regulators of T cell responses, with their overexpression causing autoimmune inflammation in animal models. As overproduction of the novel TNF superfamily ligand BAFF is associated with several autoimmune conditions, we sought to examine the potential role of BAFF as a regulator of T cell activation and effector function. We initially demonstrated BAFF costimulation of T cell activation in vitro. Generation of specific monoclonal antibodies identified BAFF-R as the only BAFF receptor present on T cells, and showed that it was expressed in an activation-dependent and subset-specific manner. Impaired BAFF costimulation in BAFF-R deficient mice indicated that BAFF-R was crucial for mediating BAFF effects in T cells. Analysis of T cell responses in vivo revealed that BAFF transgenic mice have increased T cell priming and recall responses to protein antigens, and showed a corresponding increase in the DTH model of Th1 cell-dependent inflammation. In addition, Th2-dependent allergic airway responses are suppressed in BAFF transgenic mice. Crossing to a B cell deficient background revealed that the proinflammatory effects of BAFF on T cell priming and DTH rely on the presence of B cells, while the suppressive effects during allergic airway inflammation are B cell independent. These data demonstrated that BAFF regulated the outcome of T cell responses in vivo and identified BAFF dependent crosstalk between T and B cells. Stimulation of B cells with BAFF induced the upregulation of MHC class II and ICOS-L both in vitro and in vivo. Induction of these cell surface molecules was associated with an increased capacity to induce T cell proliferation, however this effect was independent of ICOS-L expression. Thus it was demonstrated that BAFF regulated T cell activation and effector function both directly, via stimulation of BAFF-R, and indirectly, by altering the function of B cells. These data suggest that BAFF dependent alterations in T cell function may be an additional causative factor in the association between elevated BAFF levels and the generation of autoimmunity.

Thesis (Ph. D.)--Dept. of Medicine, University of Adelaide, 1990. / Typescript (Photocopy). Includes bibliographical references (leaves 202-281).

Proefschrift Groningen. / Datum laatste controle:14-04-1997. Met lit.opg. en samenvatting in het Nederlands.

Proefschrift Rijksuniversiteit Limburg, Maastricht. / Met lit. opg. en een samenvatting in het Nederlands.

Previous studies have suggested that T cell contact‐dependent signaling of macrophages (MΦ) is mediated by membrane tumor necrosis factor‐α (memTNF‐α), based on the observation that anti‐TNF‐α could inhibit T cell‐mediated MΦ activation. The current report confirms that anti‐TNF‐α does inhibit activation of interferon‐γ (IFN‐γ)‐primed MΦ by paraformaldehyde‐fixed activated T cells. However, the involvement of membrane molecules other than memTNF‐α in the contact‐dependent signaling is suggested by two lines of evidence. First, the TH2 clone, AK8, displayed neither secreted TNF‐α/β nor memTNF‐α/β detectable by bioassay or immunofluorescence. Nonetheless, AK8 cells were equally effective, on a per cell basis, in contact‐dependent signaling of MΦ activation as TH2 and TH1 cells which do express memTNF‐α. Second, the expression of memTNF‐α by the TH clone, D10.G4, is maximal 24 h after activation, whereas the ability of this clone to activate MΦ is maximal at 6–8 h of activation and declines thereafter. Since TNF‐α is known to play a critical role in activation of MΦ effector function, it was hypothesized that T cell membrane components other than memTNF‐α might signal MΦ production of TNF‐α, thus allowing autocrine TNF‐α stimulation of MΦ effector function. In support of this, it is demonstrated that paraformaldehyde‐fixed activated TH2 cells can induce de novo production and release of TNF‐α by MΦ. This effect was not an artifactual result of paraformaldehyde fixation since paraformaldehyde‐fixed resting T cells did not induce TNF‐α gene expression. Previous studies have demonstrated a role for autocrine TNF‐α stimulation in LPS induction of effector function in recombinant IFN‐γ‐primed MΦ. The current study confirms that TNF‐α plays a critical role in T cell contact‐dependent signaling of MΦ but indicates that memTNF on the T cells may not be a sine qua non factor for contact‐dependent signaling. The data suggest that other T cell membrane molecules contribute to activation of MΦ effector function by stimulation of MΦ TNF‐α production.

by Ko Samuel. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 209-227). / Abstract also in Chinese. / Acknowledgements --- p.i / Abbreviations --- p.ii / Abstract --- p.vii / Abstract in Chinese --- p.x / List of Figures --- p.xiii / List of Tables --- p.xx / Publication --- p.xxi / Contents --- p.xxii / Chapter Chapter 1. --- General Introduction --- p.1 / Chapter 1.1 --- Tumor Necrosis Factor --- p.2 / Chapter 1.1.1 --- History of Tumor Necrosis Factor --- p.2 / Chapter 1.1.2 --- TNF Subtypes and Their Purification --- p.3 / Chapter 1.1.3 --- Release of TNF --- p.9 / Chapter 1.1.4 --- Biological Actions of TNF --- p.9 / Chapter 1.2 --- Tumor Necrosis Factor Receptor --- p.11 / Chapter 1.2.1 --- Purification of TNF Receptor --- p.11 / Chapter 1.2.2 --- Regulation of TNF Receptor --- p.14 / Chapter 1.2.3 --- "Functions of TNF Receptor 1,Receptor 2 and Soluble TNF Receptors" --- p.15 / Chapter 1.3 --- Possible Signal Transductions of Tumor Necrosis Factor-Alpha --- p.17 / Chapter 1.3.1 --- Activation of Phospholipase A2 Cascade --- p.18 / Chapter 1.3.2 --- Activation of Phospho lipase C Pathway --- p.19 / Chapter 1.3.3 --- Activation of Sphingomyelin Pathway --- p.20 / Chapter 1.3.4 --- Activation of Protein Kinase --- p.22 / Chapter 1.3.5 --- Activation of the Cascade of Death Domain --- p.23 / Chapter 1.4 --- Induction of Both Necrosis and Apoptosis by Tumor Necrosis Factor-Alpha --- p.25 / Chapter 1.4.1 --- Apoptosis Versus Necrosis --- p.25 / Chapter 1.4.2 --- TNF Can Induce Both Apoptosis and Necrosis --- p.27 / Chapter 1.5 --- Possible Mechanisms of Tumor Necrosis Factor-Alpha- Mediated Cytotoxicity --- p.27 / Chapter 1.5.1 --- Release of Reactive Oxygen Species --- p.28 / Chapter 1.5.2 --- Release of Intracellular Calcium --- p.31 / Chapter 1.5.3 --- Miscellaneous Mechanisms --- p.36 / Chapter 1.6 --- Objective of Studies --- p.37 / Chapter Chapter 2. --- Materials and Methods --- p.39 / Chapter 2.1 --- Materials --- p.40 / Chapter 2.1.1 --- Buffer --- p.40 / Chapter 2.1.2 --- Culture Media --- p.45 / Chapter 2.1.3 --- Chemicals --- p.46 / Chapter 2.1.4 --- Culture of Cells --- p.49 / Chapter 2.1.4.1 --- "Tumor Necrosis Factor-Alpha-Sensitive Cell Line, L929" --- p.49 / Chapter 2.1.4.2 --- "Tumor Necrosis Factor-Alpha-Resistant Cell Line, rL929, rL929-l IE and rL929-4F" --- p.50 / Chapter 2.2 --- Methods --- p.50 / Chapter 2.2.1 --- Agarose Gel Electrophoresis --- p.50 / Chapter 2.2.2 --- Cytotoxicity Assay --- p.52 / Chapter 2.2.3 --- Confocal Laser Scanning Microscopy --- p.53 / Chapter 2.2.4 --- Flow Cytometry --- p.57 / Chapter Chapter 3. --- Results --- p.65 / Chapter 3.1 --- Induction of Apoptosis in Tumor Necrosis Factor-Alpha- Treated L929 Cell --- p.66 / Chapter 3.1.1 --- Introduction --- p.66 / Chapter 3.1.2 --- TNF Induced DNA Fragmentation in L929 Cells --- p.67 / Chapter 3.2 --- Effect of Tumor Necrosis Factor-Alpha on Cell Cycle --- p.73 / Chapter 3.2.1 --- Introduction --- p.73 / Chapter 3.2.2 --- Effect of TNF on Cell Cycle --- p.75 / Chapter 3.3 --- Release of Reactive Oxygen Species in Tumor Necrosis Factor-Alpha Treatment --- p.79 / Chapter 3.3.1 --- Introduction --- p.79 / Chapter 3.3.2 --- Release of Reactive Oxygen Species in TNF- Treated L929 Cells is Time Dependent --- p.81 / Chapter 3.3.3 --- Effect of Antioxidants on TNF-Mediated Cytotoxicity --- p.93 / Chapter 3.3.4 --- Effect of Mitochondrial Inhibitors on TNF-Mediated Cytotoxicity --- p.96 / Chapter 3.4 --- The Role of Calcium in Tumor Necrosis Factor-Alpha Treatment --- p.112 / Chapter 3.4.1 --- Introduction --- p.112 / Chapter 3.4.2 --- Release of Intracellular Calcium in TNF-Treated L929 Cells --- p.113 / Chapter 3.4.3 --- Effect of Calcium-Inducing Agents on TNF-Treated L929Cells --- p.127 / Chapter 3.5 --- Relationship between Reactive Oxygen Species and Calcium in Tumor Necrosis Factor-Alpha-Mediated Cytotoxicity --- p.133 / Chapter 3.5.1 --- Introduction --- p.133 / Chapter 3.5.2 --- Effect of Intracellular Calcium Chelator on TNF- Mediated ROS Release and Cytotoxicity --- p.133 / Chapter 3.5.3 --- Effect of Mitochondrial Calcium on TNF-Mediated ROS Release and Cytotoxicity --- p.147 / Chapter 3.6 --- Effect of Tumor Necrosis Factor-Alpha on pH --- p.162 / Chapter 3.6.1 --- Introduction --- p.162 / Chapter 3.6.2 --- Effect of TNF on pH --- p.162 / Chapter 3.7 --- Effect of Tumor Necrosis Factor-Alpha on Mitochondrial Membrane Potential --- p.165 / Chapter 3.7.1 --- Introduction --- p.165 / Chapter 3.7.2 --- Effect of TNF and Some Drugs on Mitochondrial Membrane Potential --- p.165 / Chapter 3.8 --- "Comparison of Effects of Tumor Necrosis Factor-Alpha on Susceptible Cell Line, L929 and Resistant Cell Line, rL929, rL929-11E and rL929-4F" --- p.169 / Chapter 3.8.1 --- Introduction --- p.169 / Chapter 3.8.2 --- Effect of TNF on the Cytotoxicity of Resistant Cell Lines --- p.170 / Chapter 3.8.3 --- Effect of TNF on the Release of ROS in Resistant Cell Lines --- p.170 / Chapter 3.8.4 --- Effect of TNF on the Release of Calcium in Resistant Cell Lines --- p.178 / Chapter 3.8.5 --- Effect of TNF on Cell Cycle in Resistant Cell Lines --- p.185 / Chapter Chapter 4. --- General Discussion --- p.187 / Chapter 4.1 --- Tumor Necrosis Factor Induced Apoptosis in L929 Cells --- p.188 / Chapter 4.2 --- Tumor Necrosis Factor Increased the Release of Reactive Oxygen Species in L929 Cells --- p.189 / Chapter 4.3 --- Tumor Necrosis Factor Increased the Release of Calcium in L929 Cells --- p.194 / Chapter 4.4 --- Calcium Induced Reactive Oxygen Species Release in TNF- Treated L929 Cells --- p.197 / Chapter 4.5 --- Tumor Necrosis Factor Did Not Change the pH and Mitochondrial Membrane Potential in TNF-Treated L929 Cells --- p.198 / Chapter 4.6 --- Tumor Necrosis Factor Did Not Increase the Release of Reactive Oxygen Species or Calcium in Resistant Cell Lines --- p.201 / Chapter Chapter 5. --- Future Perspective --- p.204 / Chapter 5.1 --- The Relationship Between Tumor Necrosis Factor and Cytochrome c --- p.205 / Chapter 5.2 --- The Relationship Between Tumor Necrosis Factor and Mitochondrial DNA Damage --- p.206 / Chapter 5.3 --- Clinical studies with Tumor Necrosis Factor --- p.206 / References --- p.208

No description available.

published_or_final_version / abstract / Pathology / Doctoral / Doctor of Philosophy