Le CD40 ligand (CD40L) est un régulateur important de la réponse immunitaire et un contributeur clé dans les maladies auto-immunes. Nous avons rapporté précédemment que le CD40L se liait à l’intégrine α5β1, toutefois, les conséquences fonctionnelles de cette interaction demeurent inconnues. Les lymphocytes T sont au centre de la pathogénèse des maladies auto-immunes. Ils expriment, lors de celles-ci, des quantités aberrantes d’intégrines β1 faisant en sorte que la liaison CD40L/α5β1 pourrait être d’une haute importance dans les réponses inflammatoires. Dans cette étude, nous avons démontré que la forme soluble du CD40L (sCD40L) se liait aux lymphocytes T primaires ainsi qu’aux cellules Jurkat E6.1 et ce, dépendamment de l’intégrine α5β1. L’interaction du CD40L avec l’α5β1 lymphocytaire a induit l’activation des voies anti-apoptotiques dont les MAPKs (les protéines kinases mitogène activée) et les PI3 kinases (PI3K). La liaison du sCD40L à l’α5β1 n’a pas induit son changement structural ni son adhésion à la FN (fibronectine). Ceci pourrait avoir des conséquences directes sur la survie des cellules T lors de la progression des maladies inflammatoires. Ces résultats soulignent l’impact de l’interaction CD40L/α5β1 sur la fonction biologique des lymphocytes T et ils pourraient expliquer leur survie et leur persistance au niveau des sites d’inflammations durant les maladies auto- immunes. / CD40 ligand (CD40L) is a critical regulator of the immune response and a key contributor to autoimmune diseases. We have previously reported that CD40L binds to α5β1, albeit the functional consequences of this interaction remain elusive. T cells are central to the pathogenesis of autoimmune diseases and express high levels of β1 integrins in disease conditions, making the CD40L/α5β1 interaction a potential axis of significant importance in inflammatory complications. Here, we show that soluble CD40L (sCD40L) binds to freshly isolated primary T cells and to Jurkat E6.1 T cells in a α5β1-dependant manner. This leads to the activation of key survival proteins, including the mitogen-activated protein kinases (MAPKs) and the Akt PI3 kinase (PI3K). Binding of sCD40L to α5β1 does not induce its conformational change nor allow adherence to fibronectin. These results highlight the impact of the CD40L/α5β1 interaction in T-cell function and may explain the link between sCD40L and T-cell survival and persistence in inflammatory diseases.

Thesis (Ph.D. in Immunology) -- University of Colorado at Denver and Health Sciences Center, 2006. / Typescript. Includes bibliographical references (leaves 131-146). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;

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Embora a terapia com uso de laser de baixa potência (TLBP) seja uma modalidade terapêutica amplamente estudada no meio científico, sua aplicação na clínica médica ainda gera controvérsias, já que a literatura reporta que a TLBP é capaz de promover a proliferação e diferenciação de células tumorais. O objetivo deste estudo foi avaliar os efeitos da TLBP no crescimento celular usando como modelo a linhagem B16F10 de melanoma murino em estado de homeostase e estado redox, além de verificar o comportamento quimiotáxico da linhagem B16F10 por meio do ensaio de migração transwell em resposta à TLBP em diferentes densidades de energia. Foram montados cinco grupos experimentais utilizando um laser de emissão vermelha em λ = 660 nm: Grupo controle (GC) onde nenhuma irradiação foi realizada; G30 (30J/cm2); G60 (60J/cm2); G90 (90J/cm2); G120 (120J/cm2); G150 (150J/cm2), com as respectivas doses utilizadas. Todos os experimentos foram realizados em triplicata e os resultados obtidos foram submetidos à análise estatística. Sob as condições experimentais deste estudo, nossos resultados mostram que a TLBP neste comprimento de onda não promoveu mudanças no metabolismo celular nos tempos de 48 h e 72 h, independente do estado nutricional. Foi possível observar mudança no padrão de comportamento quimiotáxico da linhagem celular B16F10 irradiadas com laser de emissão vermelha. / The low power lasers (TLBP) is a therapeutic modality widely studied in scientific field, its application in clinical medicine still generates many conflicts since literature reports proliferation in cancer cells. The objective of this study was to evaluate the effects of TLBP on cell growth using as model the line B16F10 in state of homeostasis and redox state and investigate the chemotactic behavior of B16F10 lineage through transwell migration assay in response to TLBP in different energy densities. For this purpose five experimental groups were assembled using a laser emission at λ = 660 nm: control group (G0) where no irradiation was performed; G30 (30J/cm2), G60 (60J/cm2), G90 (90J/cm2); G120 (120J/cm2); G150 (150J/cm2) with the respective doses used. All experiments were performed in triplicate and the results were statistically analyzed. Under the experimental conditions of this study, our results show that TLBP did not induced changes in cellular metabolism that influence proliferation at 48 h and 72 h, independent nutritional status. It was possible to observe changes in behavior pattern chemotactic of cell line B16F10 with TLBP at red emission.

Made available in DSpace on 2014-06-11T19:23:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-01Bitstream added on 2014-06-13T18:19:48Z : No. of bitstreams: 1 pereira_ccs_me_araca.pdf: 1524857 bytes, checksum: 29dbf40d228058d4769e3d3ef3821153 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O propósito desse trabalho foi avaliar o efeito da osteotomia para implantes sobre a viabilidade celular óssea imediata, comparando a utilização de fresas do sistema convencional com a piezocirurgia em tíbias de coelhos. Foram utilizados 6 coelhos machos, divididos em 2 etapas: (1) Fresas – 5 grupos (G1 a G5) correspondentes às osteotomias 10, 20, 30, 40 e 50 vezes, respectivamente. Cada leito ósseo recebeu a sequência de fresas: lança e helicoidais de 2,0 mm, 2,8 mm, 3,0 mm e 3,15 mm; (2) Piezocirurgia – 5 grupos (P1 a P5) correspondentes às osteotomias 10, 20, 30, 40 e 50 vezes, respectivamente, efetuadas pela sequência de pontas de 2,0 e 3,0 mm, mediante vibração ultrassônica piezoelétrica. As áreas osteotomizadas foram coletadas e processadas laboratorialmente. A análise imunoistoquímica demonstrou equilíbrio das expressões de OPG e RANKL, ou seja, formação e reabsorção óssea, tanto nas osteotomias com fresas, quanto na piezocirurgia, embora mais intensas nesta última. A expressão de OC apresentou-se bastante intensa nos grupos de piezocirurgia, mas com redução da imunomarcação a partir da 30ª osteotomia, enquanto manteve-se constante nos grupos fresados. A CAS3 evidenciou a viabilidade osteoblástica a partir da 20ª osteotomia com piezocirurgia e manteve-se constante até a 50ª. No grupo de fresas, notou-se aumento gradativo da expressão dessa proteína, conforme o aumento do número de osteotomias. De acordo com a metodologia aplicada, foi possível concluir que a piezocirurgia propicia maior viabilidade celular osteoblástica do que o sistema de fresas convencional / The purpose of this study was to evaluate the effect of the osteotomy implant on bone cell viability immediately, comparing the use of conventional drilling system with piezosurgery® in tibiae of rabbits. We used 6 male rabbits were divided into 2 stages: (1) Drilling - 5 groups (G1 to G5) corresponding to the 10 osteotomies, 20, 30, 40 and 50 times respectively. Each received a bone bed following drills: Spear drill and 2.0 mm, 2.8 mm, 3.0 mm and 3.15 mm helicoidal drills, (2) Piezosurgery® - 5 groups (P1 to P5) corresponding to the 10 osteotomies, 20, 30, 40 and 50 times, respectively, analyzed by the sequence of inserts 2 and 3 mm by piezoelectric ultrasonic vibration. The receptor-beds were collected and processed in a laboratory. The immunohistochemical analysis showed balance expressions of OPG and RANKL, ie bone formation and resorption in both the osteotomies with drills and piezosurgery®, although more intense in the latter. The expression of OC had become quite intense in piezosurgery® groups, but with reduced immunostaining from the 30th osteotomy, while remained unchanged in groups drilled. The CAS3 showed the viability of the osteoblast from the 20th osteotomy with piezosurgery® and remained constant until the 50th. In the group of drills noticed a gradual increase in the expression of this protein, as the increase in the number of osteotomies. According to the methodology, it was concluded that the piezosurgery® provides greater osteoblastic cell viability than the system of conventional drilling

Orientador: Cleverton Roberto de Andrade / Resumo: O óleo essencial de Melaleuca alternifolia (tea tree oil - TTO) é composto por aproximadamente 100 componentes, sendo que os de maior concentração são o terpinen-4-ol e gama-terpineno. Os estudos da sua capacidade citotóxica têm demonstrado efeito sobre linhagens neoplásicas malignas. O objetivo do trabalho foi avaliar a capacidade citotóxica e mutagênica do TTO e seus componentes, terpinen-4-ol e gama terpineno em culturas celulares. Duas linhagens de carcinomas espinocelulares orais e uma linhagem de ceratinócitos foram analisadas por: (1) Análise colorimétrica de Metiltetrazolium (MTT); (2) Teste do Micronúcleo. Os resultados foram expressos na forma de ensaios de susceptibilidade e grau de mutagenicidade. Posteriormente foram analisados por one-way Anova com pós-teste de Tukey. Os valores de IC50 obtidos nas análises de MTT das células expostas ao TTO foram de 0,2% para a HaCaT, 0,14% para a HSC-3 e 0,17% para a SCC-25. Para a exposição ao terpinen-4ol, os valores de IC50, foram 0,5%, 0,3% e 0,45% para as linhagens HaCaT, HSC-3 e SCC-25, respectivamente. O gama-terpineno, não demonstrou atividade citotóxica expressiva, não sendo possível calcular o IC50. O TTO não demonstrou mutagenicidade nas linhagens HaCaT e HSC-3. O terpinen-4-ol, não foi capaz de produzir mutagenicidade em nenhuma das linhagens em estudo. Conclui-se que tanto o TTO quanto o terpinen-4-ol apresentam capacidade citotóxica sobre as linhagens HaCaT, HSC-3 e SCC-25. O TTO não foi mutagênico nas linhagens... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The essential oil of Melaleuca alternifolia (tea tree oil - TTO) consists of about 100 components, and the highest concentration are terpinen-4-ol and gammaterpinene. Studies of their cytotoxic capacity have shown effect on malignant neoplastic lineages. The aim of this study was to evaluate the cytotoxic and mutagenic capacity of TTO and main soluble components, terpinen-4-ol and gama-terpinene in cell cultures. Two lineages of oral squamous cell carcinoma and a keratinocyte cell were analyzed: (1) colorimetric analysis Metiltetrazolium (MTT); (2) Micronucleus assay. The results were expressed as susceptibility tests and degree of mutagenicity. The statistical test used in the analysis was one-way ANOVA (Tukey test). The IC50 values obtained from the MTT analysis of cells exposed to TTO were 0.2% for HaCaT, 0.14% for HSC-3, and 0.17% for SCC-25. For exposure to terpinen-4ol, IC50 values were 0.5%, 0.3% and 0.45% for HaCaT, HSC-3 and SCC-25, respectively. The gamma-terpinene didn't show significant cytotoxic activity, therefore it was impossible to calculate the IC50. The TTO was unable to produce mutagenicity in HSC-3 and HaCaT. The terpinen-4-ol was not mutagenic in any of the lineages tested. In conclusion, both the TTO and terpinen- 4-ol had cytotoxic capacity on HaCaT, HSC-3 and SCC-25. The TTO was unable to produce mutagenicity in HSC-3 and HaCaT. The terpinen-4-ol was not mutagenic in any of the lineages tested. / Mestre

A estomatite protética é uma patologia que acomete muitos usuários de prótese total. Um dos principais fatores da sua etiologia é a fácil adesão de microrganismos, como a Candida albicans, à resina acrílica, principalmente devido às características de superfície facilitadoras deste material. Por esta razão, estuda-se materiais que possam modificar as características de superfície da resina acrílica sem alterar as suas propriedades mecânicas. A investigação das propriedades desses materiais, como a biocompatibilidade e como eles influenciam as células de C. albicans, é de extrema importância para uma futura aplicação clínica. Dessa forma, a proposta desta pesquisa foi avaliar a citotoxicidade sobre fibroblastos gengivais humanos (FGH) e o estresse oxidativo causado em células de C. albicans por 6 produtos (etil-cianoacrilato convencional -ECAc; etil-cianoacrilato em forma de gel formulação a -ECAga; etil-cianoacrilato em forma de gel formulação b -ECAgb; butil-cianoacrilato - BCA; octil-cianoacrilato OCA; selante tissular a base de veneno de cobra-VC;), que quando aplicados na superfície da resina acrílica, modificam suas características de superfície, visando diminuir a formação do biofilme de C. albicans. Espécimes de resina acrílica foram confeccionados e duas camadas de cada produto foram aplicadas nas superfícies. Cada espécime foi deixado em 1, 066 mL de meio de cultura durante 24 horas para extração e utilização do meio condicionado para os dois ensaios. Para a investigação da citotoxicidade, os FGH foram cultivados em placas de 96 poços, meios condicionado de cada grupo foram depositados em cada poço onde permaneceram em contato por 24, 48 e 72 h. Após o processamento para o ensaio de MTT as placas foram analisadas em espectrofotômetro a 500 nm. Foram realizados quatro experimentos independentes em triplicata (n=12). Para a investigação de estresse oxidativo (ERO) causado em C. albicans, biofilme foi desenvolvido em placas de 96 poços durante 24 h. Então, os meios condicionados foram adicionados aos poços e a placa foi mantida em agitadora durante 1 h. Após a retirada dos meios condicionados, foi adicionado a cada poço o reagente CellRox® Deep Red e leituras foram realizadas a cada 30 min durante 3 h em fluorímetro a 640/665nm. Amostras foram coletadas e ensaio de cultura microbiológica foi executado para a realização da normalização dos valores. Foram realizados 3 experimentos independentes em triplicata (n=9). Os resultados obtidos pelo ensaio MTT foram analisados por meio de ANOVA a 2 critérios, seguido pelo teste Tukey para a comparação entre grupos (p<0,05). Para o ensaio ROS, a análise estatística realizada foi ANOVA a 1 critério, seguida, igualmente, por Tukey (p<0,05). Os resultados mostraram que todos os grupos apresentaram certo grau de citotoxicidade quando comparados ao controle, com exceção do VC (ECAc&lt;ECAgb&lt;BCA&lt;OCA&lt; ECAga). O grupo ECAc em 24 e 48 h apresentou viabilidade em torno de 80%. Avaliando os tempos experimentais, a citotoxicidade demonstrou uma característica progressiva. O resultado do ERO demonstrou que todos os grupos induzem estresse oxidativo em células de C. albicans (OCA&lt;ECAc&lt;VC&lt;BCA&lt;ECAgb). Para a utilização clínica de tais produtos experimentais, estudos mais aprofundados devem ser realizados. / Denture stomatitis is a disease that affects many denture wearers. One of the main factors of its cause is the easy adhesion of microorganisms, such as Candida albicans, to acrylic resin, mainly due to its permissive surface characteristics. For this reason, materials that can modify surface characteristics of acrylic resin without changing its mechanical properties are being studied. The investigation of these materials features, such as biocompatibility and how they affect Candida albicans, is of utmost importance for future clinical application. Thus, the purpose of this study was to evaluate the cytotoxicity of human gingival fibroblasts (HGF) and oxidative stress in C. albicans cells after contact with 6 experimental products (conventional ethyl-cyanoacrylate -ECAc; ethyl-cyanoacrylate in gel formulation \"a\" -ECAga; ethyl-cyanoacrylate in gel formulation \"b\" -ECAgb; butyl- cyanoacrylate - BCA; octyl-cyanoacrylate -OCA; tissue adhesive based on snake venom -VC) applied to the surface of the resin acrylic, modifying its surface characteristics, in order to decrease C. albicans biofilm formation. Acrylic resin specimens were manufactured and two layers of each product were applied to the surfaces. Each specimen was immersed in 1,066 mL of growth media for 24 hours for extraction and the resulting conditioned media were used for both tests. To investigate cytotoxicity, HGF were cultured in 96-well plates and conditioned media from each group were deposited into each well, where they remained in contact for 24, 48 and 72h. After the MTT assay processing, plates were analyzed in a spectrophotometer at 500 nm. Four independent experiments were performed in triplicate (n=12). To investigate oxidative stress (ROS), C. albicans biofilm was developed in 96-well plates for 24 h, conditioned media were added to the wells and the plate was allowed to stir for 1 h. Then, conditioned media were removed and CellRox® Deep Red reagent was added to each well. Readings were performed every 30 min for 3 h in fluorometer at 640/665nm. Samples were collected and microbiological culture test was executed to values normalization. Three independent experiments were performed in triplicate (n=9). Results obtained in MTT assay were analyzed by two-way ANOVA and Tukey\'s test for comparison between groups (p<0.05). for comparison between groups (p<0.05). For ROS results, one-way ANOVA was performed followed by Tukey test, as well (p<0.05). The results showed that all groups presented different degrees of cytotoxicity when compared to control group, except for VC (ECAc&lt;ECAgb&lt;BCA&lt;OCA&lt;ECAga). ECAc group at 24 and 48 h showed viability about 80%. Evaluating experimental periods, the cytotoxicity showed a progressive characteristic. ROS results showed that all groups induced oxidative stress in C. albicans cells (OCA&lt;ECAC&lt;VC&lt;BCA&lt;ECAgb). For clinical use of such experimental products, further studies should be conducted.

Depuis plus d'un siècle que les rayons X ont été découverts, les effets biologiques des radiations ionisantes ne sont pas encore entièrement expliqués. Pourtant, une description précise et la modélisation mathématique des événements physico-chimiques, moléculaires et cellulaires contribueraient significativement à l'effet des risques liés à une irradiation. Le groupe de Radiobiologie de l'UMR1052 Inserm (Lyon) a accumulé un nombre considérable de données sur la radiosensibilité individuelle et la réparation des dommages radioinduits de l'ADN qui nous permettent aujourd'hui de valider des modèles nouveaux qui sont souvent en contradiction avec les paradigmes actuels. En particulier, alors que les cassures double-brin de l'ADN semblent être les dommages clés de la létalité cellulaire, aucun protocole ni biomarqueur n'est considéré comme prédictif de la radiosensibilité. Le but de la thèse a donc été de déterminer les paramètres précis qui peuvent prédire la réponse aux radiations. Un grand nombre de protéines se relocalisent sous forme de foci nucléaire autour des sites de CDB. Dans une première étape, nous avons pu proposer une formule générale qui lie induction, reconnaissance et réparation des CDB, valable pour toutes les protéines relocalisantes après irradiation. Cette formule a été appelée « Formule de Bodgi ». La validité de cette formule a pu être vérifiée sur différents biomarqueurs et sur différents types de cellules de patients montrant des radiosensibilités différentes. Dans une deuxième étape, nous avons pu modéliser le processus de transit cytonucléaire de la protéine ATM. Nous avons pu alors apporter une interprétation nouvelle et cohérente des paramètres α et β du modèle linéaire-quadratique qui décrit la relation entre la dose de radiation et la survie cellulaire. Notre théorie s'est avérée également utile pour expliquer certaines autres énigmes de la radiobiologie, notamment le phénomène d'hypersensibilité aux faibles doses / More than a century after the discovery of X-rays, the biological effects of ionizing radiation are still not entirely explained. Nevertheless, a relevant description and a mathematical model of the physico-chemical, molecular and cellular events would significantly contribute to the evaluation of the related risks. The Radiobiology Group of the UMR1052 Inserm Unit (Lyon) has collected a considerable number of data concerning individual radiosensitivity and DNA damage repair, which allows us today to validate actual modeling approaches that are often contradicting actual paradigms. Particularly, while the DNA double-strand breaks (DSB) appear to be the key-damages of cell lethality, there is still no experimental protocol or biomarker that is considered to be predictive for radiosensitivity. The purpose of this thesis was to determine the precise parameters that can predict the response to radiation. An important number of proteins relocalize as nuclear foci in the DSB sites. As a first step, we proposed a general formula that links the DSB induction, recognition and repair, valid for all the relocalized proteins after irradiation. We called this formula the ‘’Bodgi’s formula’’. The validity of this model was verified with different biomarkers, but also on different cell types from patients showing different radiosensitivity. In a second step, we proposed a model for the whole process of the nucleo-shuttling of the ATM protein that occurs after irradiation. We provided a novel and coherent interpretation of the α and β parameters of the linear-quadratic model that describes the relation between radiation dose and cell survival. Our theory was also shown to be useful in explaining some other enigmas of radiobiology, including the hypersensitivity to lowdose phenomena

O fator 2 derivado de células estromais, SDF2 (do inglês Stromal cell derived fator 2) é um gene de função ainda desconhecida, conservado em mamíferos e descrito primeiramente por Hamada et al. (1996). Neste estudo, observamos que a proteína Sdf2 de camundongo possui a alta similaridade de sequência em relação ao SDF2-like(L)1 humano e murino e de estrutura preditiva também similar em relação ao SDF2-like de Arabidopsis thaliana. A proteína mostrou-se sublocalizada no retículo endoplasmático e apresentou ampla distribuição nos tecidos e órgãos de camundongos. O mapeamento da expressão de Sdf2 ao longo da gestação humana e de camundongo nos mostrou que a proteína está presente em todas as etapas e compartimentos da placenta, com expressão em diversos tipos celulares. Nossos resultados sugerem que o SDF2 participa dos processos de diferenciação de células trofoblásticas humanas e murinas de maneira oposta. Em humanos, onde o processo é dependente da ativação de caspase-8 observou-se um aumento da expressão de SDF2. Em camundongos, onde o processo é por endoreduplicação, houve diminuição da expressão da proteína. A participação do SDF2 na via de estresse de retículo endoplasmático (RE) nas células trofoblásticas também foi analisada. Fatores adversos que podem levar à perda da homeostase do RE e levar a um acúmulo de proteínas mal enoveladas geram o fenômeno conhecido como Estresse de RE. O estresse de RE ativa a via de Resposta a Proteínas Mal Enoveladas (UPR, em inglês Unfolded Protein Response), que atua em diferentes vias de sinalização para aumentar a produção de chaperonas, a degradação das proteínas mal enoveladas e a diminuição da produção de novas proteínas. Estas respostas aumentam as chances de sobrevivência celular. Se, no entanto, a célula não recuperar sua homeostase, vias que levam à apoptose serão ativadas. A geração de estresse de RE pelo agente tunicamicina alterou significativamente a expressão de SDF2. Além disso, o silenciamento do gene SDF2 alterou a expressão dos principais fatores de controle de sobrevivência e apoptose da UPR. Desta forma, estes achados sugerem que o SDF2 desempenha um papel na regulação de sobrevivência/apoptose das células trofoblásticas pela via UPR. / The stromal cell derived factor 2 (SDF2) was first described by Hamada et al.(1996), is well conserved in mammals but its function is still unknown. In this study, we observed the predicted aminoacid sequence os Sdf2 is similar to human and mouse SDF2L1 sequence and the predicted Sdf2 structure is similar to SDF2-like from Arabidopsis thaliana. The protein is sublocalizes in the ER and it is widely expressed in mouse tissue and organs. The expression of Sdf2 throughout human and mouse gestation showed the protein is present in all gestational phases and compartments analysed and it is expressed by several cell types in the placenta. In trophoblast functional assays, SDF2 showed opposite expression patterns in human and mouse differentiation processes. In humans, where the process is dependent of caspase-8 activation, the protein is upregulated. Im mouse, the process is dependent of endoreduplication, the protein is downregulated. The participation of SDF2 in Endoplasmic Reticulum (ER) stress in trophoblastic cells was also evaluated. Adverse environmental conditions may lead to disruption of ER homeostasis causing accumulation of unfolded/misfolded proteins in ER, a phenomenon known as ER stress. ER stress activates the Unfolded Protein Response (UPR) that acts in several signaling cascades to improve chaperone production, misfolded protein degradation and to downregulate new protein production. These responses increase the capacity of cells to maintain alive even in stress conditions. Whether cells fail on restore homeostasis, the UPR activates apoptosis. We were able to observed that when gene silencing assays was used for SDF2, modifications in UPR cell survival/apoptosis markers were observed. In conclusion, we propose that SDF2 is playing a role in ER stress cell survival/apoptosis control in trophoblast cells.

Activation and proliferation of antigen-specific T cells is the hallmark of an anti-viral immune response. Effector T cells generated during an immune response are heterogeneous in regards to their ability to populate the memory pool once the immune response has resolved. Initial T cell activation takes place in the lymphoid organs, after which T cells migrate into the non-lymphoid tissues. The presence of memory T cells at non-lymphoid tissue sites has been shown to be critical for protection against secondary virus challenge. Our lab has previously demonstrated that during and after the resolution of the immune response to Lymphocytic choriomeningitis virus (LCMV) CD8+T cells in the nonlymphoid tissues are more resistant to apoptosis than those in the lymphoid organs. This stability of T cells in the non-lymphoid tissues may be critical in ensuring protection against a secondary virus challenge. Mechanisms regulating tissue-dependent differences in CD8+T cell apoptosis were studied in an acute LCMV infection model. Virus-specific CD8+T cells from lymphoid (spleen, mesenteric lymph nodes (MLN), inguinal lymph nodes (ILN)) and non-lymphoid tissues (peritoneal exudate cells (PEC), fat-pads) were compared for expression of surface antigenic markers known to correlate with a memory phenotype. Non-lymphoid tissues were enriched in IL-7Rhi, KLRG-1lo, CD27hi and CXCR3hi virus-specific CD8+ T cells, and the presence of these antigenic markers correlated with increased memory potential and survival. Transcription factors in addition to cell surface antigens were assessed as correlates of resistance to apoptosis. Virus-specific CD8+T cells in the nonlymphoid tissues were enriched in cells expressing T cell factor-1 (TCF-1), which correlated with increased memory potential and survival. CD8+T cells in the peritoneum of TCF-1-deficient mice had decreased survival during resolution of the immune response to LCMV, suggesting a role for TCF-1 in promoting survival in the non-lymphoid tissues. As an additional mechanism, I investigated whether apoptosis-resistant CD8+T cells migrate to non-lymphoid tissues and contribute to tissue-dependent apoptotic differences. CXCR3+ CD8+T cells resisted apoptosis and accumulated in the lymph nodes of mice treated with FTY720, which blocks the export of lymph node cells into the peripheral tissues. The PECs expressed increased amounts of CXCR3 ligands, CXCL9 and CXCL10, which may have recruited the non-apoptotic cells from the lymph nodes. By adoptively transferring splenic T cells into the spleen or PEC environment I showed that the peritoneal environment through a yet undefined factor promoted survival of CD8+T cells. In this study I have elucidated the mechanisms by which CD8+T cells preferentially survive in the non-lymphoid tissues. I found that non-lymphoid tissues were enriched in memory-phenotype CD8+T cells which were intrinsically resistant to apoptosis irrespective of the tissue environment. Furthermore, apoptosisresistant CD8+T cells may preferentially migrate into the non-lymphoid tissues where the availability of tissue-specific factors may enhance memory cell survival. Few transcription factors have been identified that regulate CD8+T cell effector-memory differentiation during an immune response. In this thesis, I have also studied the mechanism by which the transcription factor Blimp-1 regulates the generation of effector and memory CD8+T cells. Blimp-1 is known to repress a large number of target genes, and ChIP (chromatin immunoprecipitation) sequencing analysis done by Dr. HyunMu Shin in the lab of Dr. Leslie J. Berg identified CD25 (IL-2Rα) and CD27 as potential targets of Blimp-1. I found that Blimp-1-deficient CD8+T cells had sustained expression of CD25 (IL-2Rα) and CD27 during peak and resolution of the immune response to LCMV. By performing adoptive transfers of CD25hi and CD27hi CD8+T cells I showed that CD25 and CD27 expression on CD8+T cells during resolution of the immune response correlates with enhanced survival. Silencing Il2rα and Cd27 expression reduced the Blimp-1-deficient CD8+T cell response, suggesting that sustained expression of CD25 and CD27 was in part responsible for the enhanced CD8+T cell response seen in the Blimp-1-deficient mice. Furthermore, our collaborator Dr. HyunMu Shin showed that CD25 and CD27 are direct targets of Blimp-1, and that Blimp-1 recruits histone modifying enzymes to Il2rα and Cd27 loci to suppress their expression during the peak of the anti-viral immune response. This study identifies one of the mechanisms by which Blimp-1 regulates the balance between generation of effector and memory CD8+T cells. In this thesis work I also studied the function of the transcription factor ROG (Repressor of GATA-3) in regulating in vivo T cell responses during both acute and chronic LCMV infection. ROG-deficient mice had increased CD8+T cell responses during an acute LCMV infection. ROG deficiency also led to the generation of memory T cells with an enhanced recall response compared to WT controls. By using LCMV-specific P14+ TCR transgenic ROG-deficient CD8+T cells these defects were shown to be T cell intrinsic. ROG-deficient mice had enhanced CD8+T cell responses and viral clearance during a persistent high dose LCMV Clone 13 infection. During chronic LCMV infection ROG-deficient mice also had increased lung pathology and mortality. The results indicate that ROG negatively regulates T cell responses and memory generation during both acute and chronic LCMV infection. The studies highlighted in this thesis elucidate the mechanisms promoting CD8+T cell survival in non-lymphoid tissues as well as transcription factormediated regulation of memory CD8+T cell differentiation. Knowledge of this will help us better understand T cell immunity after infections and may eventually help develop better vaccines.