Search results for "thymus gland"
showing 10 items of 54 documents
Inhibition of T cell activityin vivo: a test model for quantitative evaluation
1976
A test model is presented which, in comparison with the conventional models of skin transplantation or graft-versus-host (GvH) reaction in mice, permits a more sensitive quantitative evaluation of T cell inhibition in vivo. Prospective donors (type AA) are immunized with prospective recipient material (type AB); the resulting T cell reaction of A versus B is inhibited by consecutive treatment. Extent of inhibition can be evaluated after transfer of the pretreated AA material onto AB recipients by calculation of remaining GvH reactivity, if compared to adequate control tranfers. In this model the target animal for T cell reactivity (the AB recipient) remains untouched from immunosuppressive …
Exclusive transduction of human CD4+ T Cells upon systemic delivery of CD4-targeted lentiviral vectors
2015
Abstract Playing a central role in both innate and adaptive immunity, CD4+ T cells are a key target for genetic modifications in basic research and immunotherapy. In this article, we describe novel lentiviral vectors (CD4-LV) that have been rendered selective for human or simian CD4+ cells by surface engineering. When applied to PBMCs, CD4-LV transduced CD4+ but not CD4− cells. Notably, also unstimulated T cells were stably genetically modified. Upon systemic or intrasplenic administration into mice reconstituted with human PBMCs or hematopoietic stem cells, reporter gene expression was predominantly detected in lymphoid organs. Evaluation of GFP expression in organ-derived cells and blood …
B cells participate in thymic negative selection of murine auto-reactive CD4+ T cells.
2010
It is well documented that thymic epithelial cells participate in the process of negative selection in the thymus. In recent years it was reported that also dendritic cells enter the thymus and contribute to this process, thus allowing for the depletion of thymocytes that are specific to peripherally expressed self-antigens. Here we report that also B cells may take part in the elimination of auto-reactive thymocytes. Using a unique mouse model we show that B cells induce negative selection of self-reactive thymocytes in a process that leads to the deletion of these cells whereas regulatory T cells are spared. These findings have direct implication in autoimmunity, as expression of a myelin…
Cutting Edge: TGF-β Induces a Regulatory Phenotype in CD4+CD25− T Cells through Foxp3 Induction and Down-Regulation of Smad7
2004
Abstract CD4+CD25+ regulatory cells are a subpopulation of T lymphocytes of thymic origin. However, recent data suggest an alternative commitment of regulatory T cells in the periphery, although the precise mechanism is unknown. In the present work, we demonstrate that TGF-β is able to induce Foxp3 expression and subsequently a regulatory phenotype in CD4+CD25− peripheral murine T cells. Similarly, TGF-β induced Foxp3 in human CD4+CD25− T cells. Moreover, we show that the inhibitory Smad7 protein that is normally induced by TGF-β and limits TGF-β signaling, is strongly down-regulated by Foxp3 at the transcriptional level. Foxp3-mediated down-regulation of Smad7 subsequently rendered CD4+CD2…
Expression of metabotropic glutamate receptors in murine thymocytes and thymic stromal cells
2000
RT-PCR combined with immunoblotting showed the expression of group-I (mGlu1 and 5) and group-II (mGlu2 and 3) metabotropic glutamate receptors in whole mouse thymus, isolated thymocytes and TC-1S thymic stromal cell line. Cytofluorimetric analysis showed that mGlu-5 receptors were absent in CD4(-)/CD8(-) but present in more mature CD4(+) CD8(+) and CD4(+)CD8(-) thymocytes. mGlu-1a receptors showed an opposite pattern of expression with respect to mGlu5, whereas mGlu2/3 receptor expression did not differ between double negative and double positive cells. mGlu receptors expressed in both thymic cell components were functional, as indicated by measurements of polyphosphoinositide hydrolysis or…
Anomalous occurrence of immunoreactive calcitonin cells in the thymus of the rat.
1982
In a study of the effect of pinealectomy on thyroid C-cell number, 8 animals out of 66 were found to have thymic tissue in close association with the thyroid. Cells containing immunoreactive calcitonin were found in all of the thyroids but in only one of the 8 pieces of thymus. These cells found in a piece of thymic tissue associated with the right thyroid lobe were located immediately under the capsule and did not form or associate with follicles. Unlike the other animals the rat with thymic calcitonin cells had an unequal distribution of C-cells between the left and right thyroid lobes, but the total number of thyroidal C-cells was the same as that of the other rats. Since the thymus prop…
T-cell-derived helper factor allows in vivo induction of cytotoxic T cells in nu/nu mice
1980
T-cell immunocompetence and diversity are thought to be generated in the thymus1,2. This view is based on the findings that (1) T-cell ontogeny is thymus dependent3,4, (2) the major histocompatibility restrictions of T-cell interactions are phenotypically related to the H–2 type of the thymus5–9, and (3) the phenotypic manifestation of H–2-linked immune responsiveness parallels the restriction elements selected in thymus10–12. However, it is unclear whether pre-thymic cells programmed to develop into T cells do already express a receptor diversity, also whether pre-thymic cells have the potential to react against self-antigens, and whether the mechanism of self-tolerance is initiated in the…
Alloreactive and H-2-restricted Lyt 23 cytotoxic T lymphocytes derive from a common pool of antecedent Lyt 123 precursors.
1980
If the collaborative requirement of Lyt 1 T helper cells is bypassed by the Lyt 1 T cell-derived mediator of T help, termed Il-2, upon antigenic stimulation, PNA+ Lyt 123 thymocytes differentiate into either alloreactive or H-2-restricted PNA- Lyt 23 cytotoxic effector cells. Along the differentiation pathway from Lyt 123 leads to 23 effector cells, cytolytic activity is carried out by T cells that still express the Lyt 123 phenotype. The data establish that Lyt 23 CTL are produced by differentiation from antecedent Lyt 123 cells.
T cell-mediated cytotoxic immune responsiveness of chimeric mice bearing a thymus graft fully allogeneic to the graft of lymphoid stem cells
1980
Fully allogeneic, chimeric mice were established by adult thymectomy of (A × B) F1animals, grafting parental A-type thymus under the kidney capsula, followed by lethal (900 rd) irradiation and reconstitution with B parental-type bone marrow cells treated with xenogeneic anti-T cell antiserum plus complement. Following in vivo sensitization with inactivated Sendai virus (SV) suspensions, no virus-specific T cells could be detected within the spleen cells of the mice. Upon stimulation with third-party allogeneic cells in a primary mixed lymphocyte culture, spleen cells of all animals generated alloreactive cytotoxic T lymphocytes (CTL). More interestingly, upon secondary in vitro stimulation …