The temperature differential of chilled water is an important factor used for evaluating the performance of a chilled water system. A low delta-T may increase the pumping energy consumption and increase the chiller energy consumption. The system studied in this thesis is the chilled water system at the Dallas/Fort Worth International Airport (DFW Airport). This system has the problem of low delta-T under low cooling loads. When the chilled water flow is much lower than the design conditions at low cooling loads, it may lead to the laminar flow of the chilled water in the cooling coils. The main objective of this thesis is to explain the heat transfer performance of the cooling coils under low cooling loads. The water side and air side heat transfer coefficients at different water and air flow rates are calculated. The coefficients are used to analyze the heat transfer performance of the cooling coils at conditions ranging from very low loads to design conditions. The effectiveness-number of transfer units (NTU) method is utilized to analyze the cooling coil performance under different flow conditions, which also helps to obtain the cooling coil chilled water temperature differential under full load and partial load conditions. When the water flow rate drops to 1ft/s, laminar flow occurs; this further decreases the heat transfer rate on the water side. However, the cooling coil effectiveness increases with the drop of water flow rate, which compensates for the influence of the heat transfer performance under laminar flow conditions. Consequently, the delta-T in the cooling coil decreases in the transitional flow regime but increases in the laminar flow regime. Results of this thesis show that the laminar flow for the chilled water at low flow rate is not the main cause of the low delta-T syndrome in the chilled water system. Possible causes for the piping strategy of the low delta-T syndrome existing in the chilled water system under low flow conditions are studied in this thesis: (1) use of two way control valves; and (2) improper tertiary pump piping strategy.

No description available.

Master of Science in Biomedical Sciences / Department of Diagnostic Medicine/Pathobiology / Jodi L. McGill / The causative agent of tuberculosis (TB) in cattle is Mycobacterium bovis (M. bovis). γδ T cells are a unique subset of nonconventional T cells that play major roles in both the innate and adaptive arms of the immune system. Bovine γδ T cells have the capacity for multiple immune functions during infection with M. bovis. However, the alternative functions of γδ T cells as well as the responses of γδ T cells in vivo at the site of infection remain unclear. To identify novel functions for γδ T cells in response to M. bovis infections, RNA sequencing and transcriptomics analysis was completed on peripheral blood γδ T cells isolated from virulent M. bovis-infected cattle. Differentially expressed genes were confirmed with real-time PCR. In an attempt to model in vivo cell-to-cell interactions at the site of infection, γδ T cells were also isolated from naïve and M. bovis-infected calves and co-cultured with autologous, BCG-infected, monocyte-derived macrophages. γδ T cell chemokine and cytokine expression was analyzed via ELISA and real-time PCR. The characteristic lesions of bovine tuberculosis are well-organized pulmonary granulomas. To determine the relevance of the RNA-sequencing and in vitro co-culture results to in vivo infection, tissue samples from granulomatous lesions in the lungs and mediastinal lymph nodes of virulent M. bovis-infected cattle were collected 3 months after infection. mRNA transcripts for γδ T cells expression of-- IFN-γ, IL-17, IL-10, IL-22, and CCL2 were microscopically evaluated within the granulomas using an in situ hybridization system, RNAScope (Advanced Cell Diagnostics Inc.). Co-culture experiments and transcriptomics analysis revealed increased expression of chemokines and various cytokines by γδ T cells responding to M. bovis infection. The novel in situ hybridization assay revealed that cytokine expression by γδ T cells varied within the lesions, with significant levels of CCL2 and IFN-γ, and low expression of IL-10, IL-22, and IL-17 in situ at this time-point after infection. Co-culture experiments also revealed that γδ T cells from virulent M. bovis-infected cattle have the capacity to directly impact the viability of M. bovis in vitro. Our results suggest that γδ T cells accumulate within the granulomas, and influence host immunity to M. bovis by secretion of cytokines and chemokines, and direct cytotoxicity, in response to infected macrophages.

CD161 γδ T-cells have been implicated in the pathogenesis of Multiple Sclerosis however their role in health and chronic liver disease requires further exploration. In health, the majority of γδ T-cells expressed CD161 – a C-type lectin, and predominantly expressed the Vδ2 chain. The CD161+ γδ T-cells demonstrated a Th1-like pattern, expressing IFN-γ, TNF-α and Granzymes/Perforin when compared to the CD161- subset. The CD161+ γδ T-cells also expressed CCR6 and IL-18R thus also displaying a Th17-like pattern. These cells were also found in the lamina propria in the gut and rapidly expanded in the 1^st few weeks of life in the periphery. On gene array analysis, there were 409 genes expressed on the CD161+ γδ T-cells when compared to their CD161-ve counterparts including those coding for β2 receptors, CCL20, Acetycholinesterase, CCR1 and IL-18R. A potential clinical correlation to cardiac diseases was found when the upregulated genes were analysed. When the CD161+ γδ and CD161+ αβ T-cell populations were compared via gene-array, an association with a risk variant for coeliac disease was found. Thus in health, CD161+ γδ T-cells are not only a distinct subset of T-cells (confirmed by a FACS approach and gene array methods), but also the expression of CD161 may be linked to common genetic signals downstream in cell processes and disease pathogenesis, irrespective of T-cell subset population. In chronic liver disease there was a significant reduction in the periphery of CD161+ γδ T-cells in patients with chronic Hepatitis C (HCV) and an increase in patients with Primary Biliary Cirrhosis and Primary Sclerosing Cholangitis when compared with healthy individuals. The CD161+ γδ T-cells appeared to be of a different phenotype in HCV infection. There was no overall significant localisation into of CD161+ γδ T-cells patients with chronic liver disease or specifically in HCV infection. There was however a CD161+ γδ T-cell enrichment in the liver in patients with Non-Alcoholic Fatty Liver disease. The CD161+ γδ T-cells were also found in Hepatocellular Carcinoma tissue. Overall it appears the CD161+ γδ T-cells are indeed a unique subset, playing a distinct role in health, as part of an early innate response, but also potentially involved in disease pathogenesis.

No description available.

Neuroblastoma is an aggressive solid tumor that develops from immature cells of the nervous system and is almost exclusively diagnosed in infants and young children. Over the past decade a multitude of immune based therapies have been explored as therapeutic candidates for patients with neuroblastoma. The anti-GD2 monoclonal antibody, 3F8, and more recently, natural kill (NK) cell based therapies have been accepted as hopeful therapeutic options for patients with Neuroblastoma. These options however have many drawbacks including dose limiting pain, the development of tolerance, reliance on MHC mismatch and possible reliance on the invariant NK (iNK) cells population. Gamma Delta T cells, a subpopulation of T cells composed of a T cell receptor (TCR) with a gamma and a delta chain instead of an alpha and a beta; chain, have been shown to recruit a more robust immune response then both 3F8 and NK cells through their activation of antigen presenting cells (APCs) and non-reliance on MHC mismatch. Gamma Delta T cells are also able to recruit NK cells as well as other cytotoxic lymphocytes. For these reasons, it is believed that Gamma Delta T cell based treatment alone or in combination with an anti-GD2 monoclonal antibody may have a greater efficacy than either NK cells or an anti-GD2 monoclonal antibody alone. The intent of this thesis is to explore and evaluate the current state of Gamma Delta T cell based immunotherapy against the backdrop of NK cell based immunotherapy for neuroblastoma.

<p>E and Id proteins are members of the basic helix-loop-helix (bHLH) transcription regulator family. These proteins control a broad range of lymphocyte biology, from the development of multiple lineages to execution of their effector functions. With the development of new experiment models, novel functions of E and Id proteins continued to be discovered. In this thesis, I focused my study on the role of Id2 in gamma delta T cells and CD4<super>+</super> alpha beta T cells, as well as the role of Id3 in B cells.</p><p> Id proteins have been shown to control gamma delta T cell development. Id3 knockout mice demonstrate a dramatic expansion of innate-like Vgamma1.1<super>+</super> Vdelta6.3<super>+</super> T cells in the neonatal stage, suggesting that Id3 is an inhibitor of their development. Interestingly, Id3 knockout mice with a B6/129 mix background have much less expansion of the Vgamma1.1<super>+</super> Vdelta6.3<super>+</super> T cells compared to mice with pure B6 background. Genetic studies showed that this difference is strongly influences by a chromosome region very close to the Id2 locus. Using the Id2<super>f/f</super> CD4Cre<super>+</super> mice, I found that Id2 is also an inhibitor of gamma delta T cell development. Deletion of Id2 alone is sufficient to enhance the maturation of these cells in the thymus and induce a moderate expansion of gamma delta T cells in the periphery. This study demonstrated the delicate balance of transcription control in cells of the immune system.</p><p> The Id2<super>f/f</super> CD4Cre<super>+</super> mice also enabled me to study the role of Id2 in peripheral CD4<super>+</super> alpha beta T cell functions, which was difficult in the past because Id2 knockout mice lack lymph node development. I found that CD4 T cells in these mice have a profound defect in mounting immune responses, demonstrated by a complete resistance to induction of experimental autoimmune encephalomyelitis (EAE). I found that Id2-deficient CD4 T cells fail to infiltrate the central nervous system, and the effector CD4 T cell population is smaller compared to that in control mice. Id2 is important for the survival and proliferation of effector CD4 T cells, and this phenotype was correlated with an increased expression of <italic>Bim</italic> and <italic>SOCS3</italic>. This study revealed a novel role of Id2 in the functioning of CD4<super>+ </super>alpha beta T cells.</p><p> Switching my focus to B cells, recent next generation sequencing of human Burkitt lymphoma samples revealed that a significant proportion of them have mutations of Id3. This finding suggests that Id3 may be a tumor suppressor gene in the lymphoid system. Utilizing various Id3 knockout and conditional knockout mouse models, I showed that Id3 deficiency can accelerate lymphoid tumor genesis driven by the over-expression of oncogene c-Myc. This work may lead to development of a more realistic mouse model of human Burkitt lymphoma, allowing more mechanistic studies and perhaps preclinical tests of new therapies.</p> / Dissertation

<p>Although well established that human Vγ9Vδ2 T cells may expand in circulation during intracellular bacterial infections, most underlying studies included only a few cases and only some diseases had been studied so far. In tularemia, a severe invasive disease, only one patient had been described. Legionellosis, including the mild flue-like Pontiac disease caused by Legionella micdadei, had not been studied at all. The aim of the present thesis was to study the circulatory Vγ9Vδ2-T cell response in these two intracellular bacterial diseases. The number of cases included was large enough to draw general conclusions. At various intervals, Vγ9Vδ2-T-cell counts and the capability of the cells to produce proinflammatory cytokines were assayed. Finally, the nature of the stimulating antigens was determined.</p><p>In the acute phase of tularemia, we showed a marked increase of circulatory Vγ9Vδ2 T cells. When 181 samples from 108 patients with ulceroglandular tularemia were assayed, the percentage of Vγ9Vδ2 T cells was found to increase from ~5 to > 20% after the first week of disease. During the ensuing 24 months, levels were normalized. Vaccination with the live attenuated vaccine strain Francisella tularensis LVS, on the other hand, did not cause an increase in numbers of Vγ9Vδ2 T cells.</p><p>Within an outbreak of Pontiac fever, 14 cases were well defined with regard to incubation time and onset of disease. In samples obtained 4 to 6 days after onset of disease, the mean percentage of Vγ9Vδ2 T cells was ~ 1%, i.e., 20% of normal values. Thereafter, a pronounced increase occurred and at 2 to 7 weeks after onset of disease, values were ~ 15%. Later, values slowly decreased. In both tularemia and Pontiac fever, the capacity of Vγ9Vδ2 T cells to produce TNF-α in response to phorbol myristate acetate in vitro was transiently decreased, in tularemia up to 6 weeks after onset of disease and in Pontiac fever in samples obtained 5-7 weeks after onset of disease.</p><p>Nonpeptidic pyrophosphorylated molecules, referred to as phosphoantigens, are powerful stimuli for Vγ9Vδ2 T cells. Various strains of F. tularensis, including LVS, and a strain of L. micdadei were shown to produce Vγ9Vδ2 T-cell stimulating phosphoantigen. Notably, stimulation with an extract from each agent caused a similar degree of expansion of cells from subjects infected with the homologous and heterologous agent and also of cells from healthy subjects. Thus no immunospecific memory was detected in the Vγ9Vδ2-T cell response.</p><p>Since it had been suggested that homologs of the conserved heat shock protein, chaperon-60, may be recognized by human Vγ9Vδ2 T cells, we determined the subpopulation of T cells responding to this protein as well as to DnaK, another heat-shock protein. Under in vitro conditions allowing a vigorous expansion of Vγ9Vδ2 T in response to a phosphoantigen, no expansion of γδ T cells in response to Cpn60 or DnaK of F. tularensis occurred. αβ T cells of tularemia-primed subjects, on the other hand, responded vigorously to the heat-shock proteins.</p><p>In conclusion, two intracellular bacterial diseases with widely varying clinical expression were both associated with expansion of circulating Vγ9Vδ2 T cells. The expansion was prominent, long-lasting, and consistent within large numbers of individuals tested. In Pontiac fever, the expansion of Vγ9Vδ2 T cells was preceded by a depletion of the cells in circulation, implicating a possible extravasal migration into an infected site before the occurrence of rapid expansion and reentrance to blood. Both in tularemia and Pontiac fever, a modulation of the cytokine expression of Vγ9Vδ2 T cells was demonstrated in vitro, suggesting the presence of modulation of the inflammatory response. In extracts from in vitro culture of F. tularensis and L. micdadei, Vγ9Vδ2 T-cell stimulating phosphoantigens were identified and according to cross stimulation experiments, they induced expansion in vitro of Vγ9Vδ2 T cells without regard to immunospecific memory.</p>

Although well established that human Vγ9Vδ2 T cells may expand in circulation during intracellular bacterial infections, most underlying studies included only a few cases and only some diseases had been studied so far. In tularemia, a severe invasive disease, only one patient had been described. Legionellosis, including the mild flue-like Pontiac disease caused by Legionella micdadei, had not been studied at all. The aim of the present thesis was to study the circulatory Vγ9Vδ2-T cell response in these two intracellular bacterial diseases. The number of cases included was large enough to draw general conclusions. At various intervals, Vγ9Vδ2-T-cell counts and the capability of the cells to produce proinflammatory cytokines were assayed. Finally, the nature of the stimulating antigens was determined. In the acute phase of tularemia, we showed a marked increase of circulatory Vγ9Vδ2 T cells. When 181 samples from 108 patients with ulceroglandular tularemia were assayed, the percentage of Vγ9Vδ2 T cells was found to increase from ~5 to &gt; 20% after the first week of disease. During the ensuing 24 months, levels were normalized. Vaccination with the live attenuated vaccine strain Francisella tularensis LVS, on the other hand, did not cause an increase in numbers of Vγ9Vδ2 T cells. Within an outbreak of Pontiac fever, 14 cases were well defined with regard to incubation time and onset of disease. In samples obtained 4 to 6 days after onset of disease, the mean percentage of Vγ9Vδ2 T cells was ~ 1%, i.e., 20% of normal values. Thereafter, a pronounced increase occurred and at 2 to 7 weeks after onset of disease, values were ~ 15%. Later, values slowly decreased. In both tularemia and Pontiac fever, the capacity of Vγ9Vδ2 T cells to produce TNF-α in response to phorbol myristate acetate in vitro was transiently decreased, in tularemia up to 6 weeks after onset of disease and in Pontiac fever in samples obtained 5-7 weeks after onset of disease. Nonpeptidic pyrophosphorylated molecules, referred to as phosphoantigens, are powerful stimuli for Vγ9Vδ2 T cells. Various strains of F. tularensis, including LVS, and a strain of L. micdadei were shown to produce Vγ9Vδ2 T-cell stimulating phosphoantigen. Notably, stimulation with an extract from each agent caused a similar degree of expansion of cells from subjects infected with the homologous and heterologous agent and also of cells from healthy subjects. Thus no immunospecific memory was detected in the Vγ9Vδ2-T cell response. Since it had been suggested that homologs of the conserved heat shock protein, chaperon-60, may be recognized by human Vγ9Vδ2 T cells, we determined the subpopulation of T cells responding to this protein as well as to DnaK, another heat-shock protein. Under in vitro conditions allowing a vigorous expansion of Vγ9Vδ2 T in response to a phosphoantigen, no expansion of γδ T cells in response to Cpn60 or DnaK of F. tularensis occurred. αβ T cells of tularemia-primed subjects, on the other hand, responded vigorously to the heat-shock proteins. In conclusion, two intracellular bacterial diseases with widely varying clinical expression were both associated with expansion of circulating Vγ9Vδ2 T cells. The expansion was prominent, long-lasting, and consistent within large numbers of individuals tested. In Pontiac fever, the expansion of Vγ9Vδ2 T cells was preceded by a depletion of the cells in circulation, implicating a possible extravasal migration into an infected site before the occurrence of rapid expansion and reentrance to blood. Both in tularemia and Pontiac fever, a modulation of the cytokine expression of Vγ9Vδ2 T cells was demonstrated in vitro, suggesting the presence of modulation of the inflammatory response. In extracts from in vitro culture of F. tularensis and L. micdadei, Vγ9Vδ2 T-cell stimulating phosphoantigens were identified and according to cross stimulation experiments, they induced expansion in vitro of Vγ9Vδ2 T cells without regard to immunospecific memory.

Le cytomégalovirus (CMV) est l’agent responsable de l’infection opportuniste la plus fréquemment rencontrée en transplantation d’organe. Chez les receveurs séronégatifs qui reçoivent un rein provenant d’un donneur séropositif, 50 % de ces patients peuvent développer une virémie, et 30 % une maladie. A court terme, malgré les traitements anti-viraux, elle est responsable d’une morbidité non négligeable. A long terme, le CMV est associé à une augmentation de la fréquence des sténoses artérielles, plus d’infections associées, plus de rejet aigu, plus de lésions de fibrose interstitielle et d’atrophie tubulaire, une moins bonne survie des greffons et des patients. La cohabitation et la coévolution du CMV avec l’homme depuis des milliers d’années ont aboutie à un état d’équilibre entre le virus et son hôte. Le virus s’est profondément adapté à son hôte afin d’échapper à la réponse immune. En réponse à cela, la réponse immunitaire anti-CMV occupe une part unique et majeure au sein de la réponse immune de l’hôte. Les lymphocytes T CD8+ spécifiques du CMV représentent par exemple 10.2% des lymphocytes T CD8+ mémoires. Avec l’âge, ils s’accumulent et peuvent représenter jusqu’à 30% du pool total de lymphocyte T CD8+. Le système immunitaire sous la contrainte du virus s’est donc refaçonné de façon à garder le contrôle du virus. Depuis 1999, un nouvel acteur de cette réponse immunitaire a été identifié : les lymphocytes T gamma delta Vdelta2-negative. Ces cellules sont impliquées habituellement dans la lutte contre les différents stress d’origine microbien et non microbien (tumeur). Elles interviennent plutôt localement (dans les épithéliums) par différents mécanismes et sont désormais considérées comme des effecteurs intermédiaires entre l’immunité innée et l’immunité adaptative. Leur expansion dans le sang est associée à la guérison de la maladie et à la résolution de l’infection à CMV. Elles ont par ailleurs in vitro une réactivité croisée contre des cellules infectées par le CMV et des cellules tumorales. Les lymphocytes T gamma delta Vdelta2-negative sont donc une représentation supplémentaire de l’énorme impact du CMV sur le système immunitaire de l’hôte. Dans ce travail, nous avons pu étendre et approfondir leur rôle en transplantation d’organe. Nous avons tout d’abord décrit que les lymphocytes T gamma delta Vdelta2-negative avaient un phénotype et une cinétique d’expansion exactement superposable aux lymphocytes T CD8+ spécifiques du CMV in vivo. Nous avons ensuite observé que l’expansion des lymphocytes T gamma delta Vdelta2-negative induits pas l’infection à CMV s’associait à une survenue moindre de cancer à long terme chez les patients transplantés rénaux. Nous avons pu montrer que leur activation était sous la dépendance d’une interaction entre leur TCR et un ligand. Enfin, une autre voie d’activation dépendante du CD16, faisant intervenir les complexes immuns CMV-IgG anti-CMV a aussi été identifiée. Nos travaux depuis 10 ans ont donc démontré que les lymphocytes T gamma delta Vdelta2-negative occupaient une place majeure dans la réponse immune anti-CMV au même titre que les lymphocytes T CD8+. L’intégration de ces cellules à l’immunologie anti-CMV devrait permettre de mieux comprendre certains effets indirects induits par le virus, et pourrait être utile dans le suivi de la réponse immune anti-CMV en transplantation d’organe. L’identification de leur ligand pourrait permettre enfin de tester assez rapidement de nouveaux protocoles d’immunothérapie anti-virale ou anti-tumorale. / Cytomegalovirus (CMV) infection is the most frequent opportunistic infection encountered in solid-organ transplantation. Fifty percent of seronegative kidney transplant recipients (KTR) who receive a kidney from a seropositive donor may develop a CMV infection which causes a disease in 30% of cases. In the long term, CMV is associated with an increased incidence of arterial stenosis, more opportunistic infections, more acute rejection episodes, more interstitial fibrosis and tubular atrophy, and a poorer graft and patient survivals. For thousands years, the co-evolution between the CMV and the immune system allowed to a state of equilibrium between the virus and the host. The virus has deeply adapted to its host in order to escape the immune response. In response, the anti-CMV immune reaction takes up an important and unique place. For example, the CMV-specific CD8+ T cells represent an average 10.2% of the memory CD8+ T cell compartment in CMV-seropositive healthy individuals. With age, these cells accumulate and can represent around 30% of CD8+ T lymphocytes. Therefore under the long-lasting pressure of the virus, the immune system has redesigned in order to keep the control of the virus. Since 1999, a new actor was identified within the immune system: the Vdelta2-negative gamma delta T cells. These cells are involved against various microbial and non microbial stresses. They act locally in epithelia by different mechanisms and are now considered as intermediate effectors between innate and adaptive immunity. In vivo in KTR, their blood expansion is associated with the resolution of CMV infection. In vitro, they share a cross-reactivity against CMV-infected cells and tumor cells. Therefore, the Vdelta2-negative gamma delta T cells are new representatives of the huge impact of CMV on the host immune system. In this work, we were able to extend and get further insight into their role in organ transplantation. In vivo, we first described that Vdelta2-negative gamma delta T cells displayed a phenotype and an expansion kinetic similar to that of CMV-specific CD8+ T cells. Next, we observed that the CMV-induced Vdelta2-negative gamma delta T cells expansion was associated with a lower occurrence of cancer in long-term KTR. In vitro, experiments of transfer of gamma delta TCR allowed us to show that their activation against tumor ligands was TCR-dependent and that different tumor ligands could be recognized by each Vdelta2-negative gamma delta TCR studied. In addition, we observed that the recognition of CMV-infected cells was not only TCR-dependent, but under the dependence of a multi molecular complex involving co stimulatory signals. Finally, we also identified a new CD16-dependent pathway of activation in gamma-delta T cells, involving IgG-opsonised CMV. In summary, Vdelta2-negative gamma delta T cells take up a major place within the anti-CMV immune response in addition to CD8+ T lymphocytes. The integration of these cells to the anti-CMV immunology should provide a better understanding of some indirect effects of the virus and could be useful to monitor the immune response against CMV in solid-organ transplant recipients. Moreover, identification of their ligands could provide interesting tools for new protocols of anti-CMV and anti-tumor immunotherapy.