Browsing by Subject "T cell"
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Item Developing novel strategies to enhance thymic recovery and T-cell reconstitution following bone marrow transplantation.(2009-05) Kelly, Ryan MichaelAllogeneic HSCT is a valuable treatment option for many malignant and nonmalignant disorders. A significantly limiting factor for a favorable outcome following HSCT is the prolonged T-cell deficiency following transplant, which is primarily due to thymic injury caused by the intense chemotherapy/radiation-conditioning regimen given prior to transplant. The submitted work details the development of novel approaches to restore thymic function and enhance T-cell reconstitution following bone marrow transplantation (BMT). The preclinical research described in this dissertation investigates the therapeutic potential of combinatorial administration of keratinocyte growth factor, androgen regulators and general radioprotectants in restoring thymic function and T-cell reconstitution following BMT. The data suggest that pre-conditioning treatment of BMT recipients with combinations of these agents lead to rapid and durable restoration of thymic function and accelerated peripheral reconstitution of donor-derived, naïve CD4 and CD8 T-cells. Importantly, enhanced T-cell reconstitution correlates with superior antigen-specific CD4 and CD8 T-cell responses in vivo. This work also describes research aimed at characterizing the kinetics of depletion and recovery of thymic epithelial cells (TEC) following BMT and elucidating the role of thymocyte:TEC crosstalk in promoting TEC regeneration. A more thorough understanding of this process will allow for the identification of more focused targets for therapies aimed at promoting thymic and T-cell reconstitution following BMT. Taken together, this work has generated novel findings that will advance the field of immune reconstitution following bone marrow transplantation.Item Evaluating memory CD8 T cell quantity, distribution and migration(2016-08) Steinert, ElizabethMemory CD8 T cells protect against intracellular pathogens by scanning host cell surfaces, thus infection detection rates depend on memory cell number and distribution. Many cell population analyses rely on isolation from whole organs and interpretation is predicated on presumptions of near-complete cell recovery. Paradigmatically, T cell memory is parsed into central, effector, and resident subsets, ostensibly defined by immunosurveillance patterns, but in practice identified by phenotypic markers. Because isolation methods and subsequent phenotypic marker-based analyses ultimately inform models of memory T cell differentiation, protection, and vaccine translation, we tested their validity via quantitative immunofluorescence microscopy of a murine memory CD8 T cell population. We found that lymphocyte isolation fails to recover most cells and recovery is biased against certain subsets. Applying this approach to parabiotic mice we found that the overwhelming majority of memory CD8 T cells in non-lymphoid tissues are resident, rather than recirculating. Residence was not absolutely predicted by common phenotypic markers (CD103 & CD69), a finding that demonstrates heterogeneity in the resident memory population and insists that migration rather than solely phenotype be used for identification. Despite tissue-specific immune regulation, establishment of resident memory CD8 T cells was extended to male genital tract tissues, where they maintain local cytokine production in the presence of rechallenge. Our studies of male genital tract organs revealed non-canonical migration of effector CD8 T cells directly into visceral non-lymphoid tissues of recently infected mice. Together, these results provide a systematic quantification of the distribution and compartmentalization of virus-specific memory CD8 T cell subsets and highlight the relative numerical abundance of resident memory CD8 T cells, indicating that host immunosurveillance by memory CD8 T cells is conducted in a highly localized manner.Item Immunopathogenesis of avian metapneumovirus in the Turkeys(2009-09) Cha, Ra MiAvian metapneumovirus subtype C (aMPV/C) causes a severe upper respiratory tract (URT) disease in turkeys. The disease is characterized by viral replication and extensive lymphoid cell infiltrations in the URT. The identity of infiltrating cells and their possible involvement in the immunopathogenesis of the disease are not known. The role of local mucosal immunity in viral defense has not been examined for aMPV/C. The overall objective of the study was to examine the immunopathogenesis of aMPV/C in ovo and hatched turkeys, with emphasis on the involvement of local mucosal immunity in viral defense. Three specific objectives were pursued. First, the immune cells, especially mucosal T cells that infiltrate the URT of turkeys following aMPV/C exposure were characterized. Two-week-old aMPV/C antibody-free turkeys were inoculated oculonasally (O/N) with live aMPV/C. At 5 and 7 days post inoculation (DPI), lymphoid cells infiltrating the mucosal lining of the turbinates of the virus-exposed and untreated control turkeys were isolated by enzymatic treatment. In the URT, aMPV/C exposure increased the proportion of CD8+ T cells but not of CD4+ T cells. In addition, CD8 gene expression was upregulated after virus exposure whereas CD4 gene expression remained unchanged. At 5 and 7 DPI, aMPV/C-exposed turkeys showed upregulated gene expression of IFN-gamma and IL-10 in the turbinate tissue. These results suggested that aMPV/C modulated local cellular immunity in the URT of turkeys. Secondly, the ability of an adjuvanted inactivated aMPV/C (Ad-iaMPV/C) inoculated by the respiratory route to induce protective mucosal immunity in the URT was examined. aMPV/C antibody-free turkeys were inoculated via the O/N route with inactivated virus adjuvanted with synthetic double-stranded RNA polyriboinosinic polyribocytidylic acid (Poly IC). Ad-iaMPV/C immunized turkeys showed an increased number of mucosal IgA+ cells in the URT and increased levels of virus-specific IgG and IgA in the lachrymal fluid and serum. After 7 or 21 days post immunization, turkeys were challenged with pathogenic aMPV/C via the O/N route. Turkeys immunized with Ad-iaMPV/C were protected against microscopic lesions and the replication of the challenge virus in the URT. These observations revealed that inactivated aMPV/C administered by the respiratory route induced protective immunity against challenge with the pathogenic virus. As the last objective, we studied the immunopathogensis and protective immunity of aMPV/C in turkeys following in ovo exposure. aMPV/C was inoculated into commercial aMPV/C antibody-free turkey eggs via the amniotic route at embyronation day (ED) 24. Hatchability of eggs was not affected by the virus inoculation. At the day of hatch (ED 28) (4DPI) and 5 days post hatch (9DPI), the virus genome was detected by qRT-PCR in the turbinate, trachea and lung but not in the thymus or the spleen. Turbinate mucosa had mild lymphoid cell infiltration, and there were no detectable lesions in the lung. Spleen cells and thymus cells from virus-exposed turkeys responded poorly to T cell mitogens. In addition, IFN-gamma and IL-10 gene expression was increased in the turbinate tissue of virus-exposed turkeys. In ovo virus exposure increased the levels of aMPV/C-specific IgG in the serum and the lachrymal fluid. At 3 weeks of age, the in ovo immunized turkeys were protected against a challenge with pathogenic aMPV/C. These data indicated that in ovo vaccination may be used in turkeys to control aMPV/C.Item The role of HIV- and SIV-specific CD8+ T cells in the establishment of persistent HIV and SIV infections.(2009-12) Mattila, Teresa LeaCD8+ T cells are important in controlling viral infections. Although the appearance of HIV-specific CD8+T cells initially correlates with reduced viral load during HIV infection, for unknown reasons HIV is never fully cleared from the body. My central hypothesis is that B cell follicles are sites in which virus-producing cells are protected from virus-specific CD8+T cells. During the chronic stages of infection the majority of HIV-producing cells accumulate in B cell follicles. The localization and abundance of HIV-specific CD8+T cells relative to B cell follicles is not known. For these studies I determined the spatial localization of HIV and SIV-specific CD8+T cells relative to B cell follicles in lymph nodes from HIV-infected humans and SIV-infected rhesus macaques, using immunohistochemistry, in situ tetramer staining, confocal microscopy, and quantitative image analysis. My findings show that most HIV-specific CD8+T cells were concentrated in T cell zones and were largely excluded from areas within B cell follicles where HIV is concentrated. Because many similarities exist between HIV infection in humans and SIV infection in macaques, and SIV model systems are essential tools to understanding HIV/SIV infections and for the development of HIV vaccines, we set out to determine whether the exclusion of virus-specific CD8+T cells from B cell follicles also occurs in the SIV/rhesus macaque model of HIV infection. I found in a small cohort of animals that during the early and late stages of SIV infection, SIV-specific CD8+ T cells were concentrated in T cell zones of lymph nodes, and that within B cell follicles, concentrations of SIV-specific CD8+T cells were significantly lower than in T cell zones. Most B cell follicles showed an absolute exclusion of SIV-specific T cells from more than half of the B cell follicle area where SIV concentrates. These data support the hypothesis that B cell follicles are an immune privileged site in which HIV/SIV-producing cells are protected from HIV/SIV-specific CD8+T cells. These data have important implications for the development of a successful HIV vaccine and treatments to eradicate HIV.