CD4 co-receptor of main T cell receptor (TCR) is essential for proper development of T lymphocytes and their function in adaptive immune responses. It is believed that CD4 stabilizes the interaction of TCR with antigenic ligand, peptide-MHC, and thereby improves T cell-dependent responses during immune reaction. CD4 is transmembrane glycoprotein with a number of structural motifs in its intracellular domain which do not dramatically affect its sorting to the plasma membrane but can influence its local organization at nanoscale. CD4 was shown to transiently accumulate in the immunological synapse formed between T cell and antigen-presenting cell. Such accumulation is rapidly followed by its internalization and/or delocalization outside the synapse. This is in contrast with TCR which accumulates strongly in the immunological synapse and is later found enriched in the central area of this structure. It is therefore unclear how TCR and its CD4 co-receptor function together when binding to their common ligand during the initiation of signaling in T cells. We aim to study localization of CD4 at nanoscale using advanced fluorescence microscopy techniques achieving significant improvements in resolution. In this work, CD4 and its mutant variants, potentially causing its different localization at the...

Les Contrôleurs du VIH sont de rares individus capables de contrôler spontanément la réplication virale en l’absence de traitement. De nombreuses études montrent que les Contrôleurs développent des réponses T antivirales remarquablement efficaces. Les cellules T CD4+ spécifiques de Gag pourraient jouer un rôle particulier car cette population est préservée en comparaison aux patients traités et corrèle négativement avec la charge virale. Afin d’étudier cette population, nous avons réalisé une analyse transcriptionnelle et protéique multiplexée sur cellule unique, à partir de cellules T CD4+ détectées ex vivo par marquage tétramère de CMH-II contre le peptide Gag293 (Tet+). Nous avons comparé l’expression de 44 gènes et 6 protéines membranaires chez 9 patients Contrôleurs et 9 patients traités. Nous avons d’une part validé la forte fréquence de cellules T CD4+ Tet+ chez les Contrôleurs en comparaison aux patients traités et, d’autre part, montré que les cellules T CD4+ Tet+ des Contrôleurs, étaient activées et engagées dans une différenciation Th1 avancée et présentant un profil cytotoxique. De plus, les cellules T CD4+ Tet+ de Contrôleurs ont montré un état d’épuisement limité, reflété par une expression faible de PD-1, qui pourrait être l’une des raisons du maintien de leur fréquence et de leurs fonctions. Dans une deuxième étude, nous avons étudié les cellules T folliculaires « helper » (Tfh) dans la population T CD4+ spécifique de Gag chez les Contrôleurs du VIH. Les Tfh jouent un rôle essentiel dans la maturation d’affinité des anticorps en aidant les cellules B. Afin de déterminer si ce sous-type cellulaire joue un rôle dans le contrôle de l’infection à VIH, nous avons analysé le phénotype et la fonction des Tfh circulantes (cTfh) : cellules T CD4+ CD45RA- CXCR5+). Nous avons utilisé un marquage tétramère de CMH-II contre le peptide Gag293, pour détecter les cTfh spécifiques du VIH (cTfh Tet+), et nous avons montré que cette population est préférentiellement maintenue chez les Contrôleurs du VIH. L’analyse phénotypique de la population cTfh Tet+ a montré une intensité d’expression (MFI) de PD-1 plus importante dans le groupe de patients traités, suggérant une activation immune anormale chez ces patients. La fonction des cTfh, analysée pour leur capacité à induire la sécrétion d’IgG en coculture avec des cellules B mémoires autologues, n’a pas montré de différences majeures entre les groupes en terme de production d’IgG totales. Cependant, la production d’IgG spécifiques anti-VIH est significativement plus efficace chez les Contrôleurs, en particulier pour la réponse anti-Env qui est plus de 30 fois supérieure à celle des patients traités. Enfin, la fréquence des cTfh Tet+ a corrélé positivement avec la production d’IgG spécifiques, supportant l'idée d'un rôle important de la fonction Tfh dans la réponse humorale anti-VIH. L’ensemble de ces résultats indique que la population T CD4+ spécifique de Gag supporte chez les Contrôleurs les deux bras de la réponse immunitaire antivirale : d’une part, une réponse de type cellulaire Th1 montrant un profil cytotoxique et, d’autre part, une réponse de type humorale, reflétée par des interactions cTfh/B préservées, résultant en une réponse B mémoire vigoureuse. Le maintien de la fonction et de la fréquence de ces cellules spécifiques de Gag pourrait donc jouer un rôle important dans le contrôle du VIH / HIV Controllers are rare individuals able to spontaneously control viral replication in the absence of treatment. Several studies showed that controllers develop effective anti-viral T cell responses. Gag-specific CD4+ T cells could play a particular role in HIV control, because this population is preserved in comparison with the treated patients and correlates negatively with the viral load. In order to study this population, we performed a multiplexed single cell transcriptional and protein analysis from CD4+ T cells detected ex vivo by MHC-II tetramer labeling against the Gag293 peptide (Tet+). We compared the expression of 44 genes and 6 surface proteins in 9 Controllers patients and 9 treated patients. Firstly, we validated the high frequency of Tet+ CD4+ T cells in controllers compared to the treated patients, then we showed that Tet+ CD4+ T cells from controllers were activated and engaged in advanced Th1 differentiation with a cytotoxic profile. In addition, Tet+ CD4+ T cells from controllers showed a limited state of exhaustion, reflected by a lower expression of PD-1, which could be one of the reasons for maintaining their frequency and functions. In a second study, we studied follicular helper T cells (Tfh) among the Gag-specific CD4+ T cell population of HIV controllers. Tfh plays an essential role in the affinity maturation of the antibody response by providing help to B cells. To determine whether this CD4+ T cell subset may contribute to the spontaneous control of HIV infection, we analyzed the phenotype and function of circulating Tfh (cTfh: T cells CD4+ CD45RA- CXCR5+). We performed a MHC-II tetramer labeling against Gag293 peptide to detect HIV-specific cTfh (cTfh Tet +), and showed that this population is preferentially maintained in HIV controllers. Phenotypic analysis of Tet+ cTfh population showed a higher intensity of PD-1 expression (MFI) in the treated group suggesting abnormal immune activation in these patients. The function of cTfh, analyzed by the capacity to promote IgG secretion in cocultures with autologous memory B cells, did not show major differences between groups in terms of total IgG production. However, the production of HIV-specific IgG is significantly more efficient in the controller group, especially for the anti-Env response that is more than 30-fold greater than those of the treated patients. Finally, the frequency of Tet+ cTfh correlated positively with the production of specific IgG, supporting the idea of an important role of Tfh function in the humoral antiHIV response. Taken together, these results indicate that Gag-specific CD4+ T cell population supports the two arms of the antiviral immune response in HIV controllers: the cell-mediated response through a preferential differentiation toward Th1 cell type showing a cytotoxic profile, and the humoral response, reflected by preserved cTfh / B interactions, resulting in a vigorous memory response. Maintaining the function and frequency of these Gag-specific CD4+ T cells could therefore play an important role in HIV control

Lic.-avh. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 3 uppsatser.

Diss. (sammanfattning) Umeå : Umeå universitet, 2010.

Les alliages intermétalliques réfractaires à base de niobium sont considérés comme ayant un bon potentiel pour les applications à haute température grâce à un bon compromis entre une bonne résistance à haute température et une bonne ductilité à température ambiante. En outre, cette famille d'alliages présente également un point de fusion élevé et une faible densité. De ce fait, ils sont de bons candidats pour les applications dans les aubes de turbine à basse pression pour une plage de température comprise entre 800 et 1000 ° C. Le but de cette étude est d'étudier les changements de composition chimique, en particulier la précipitation de phase O-Ti2AlNb et les effets d'addition de silicium sur les microstructures et les propriétés mécaniques à haute température. L’étude commence par une première prospective sur les alliages montrant le plus de potentiel pour les applications visées. Les alliages étudiés doivent présenter un bon équilibre entre ductilité induite par le titane qui empêche la précipitation de la phase d-Nb3Al fragile, et une quantité élevée de niobium pour maintenir de bonnes propriétés mécaniques à haute température. Les alliages étudiés sont dopés avec 1 %at Si pour améliorer la résistance aux températures élevées et maintenir une ductilité acceptable à température ambiante. Nous nous intéressons également à l’influence des teneurs en aluminium et silicium sur les transformations de phase. Le système est renforcé par mise en ordre A2 ? B2, par effet de solution solide ou par durcissement structural de la phase O-Ti2AlNb. La cinétique de précipitation de cette phase O-Ti2AlNb est dépendante de la composition chimique. En particulier l’ajout de silicium permet un élargissement du domaine de précipitation et accélère sa cinétique de précipitation. / Niobium based refractory intermetallic alloys are considered as having great potentials for high temperature applications based on a good balance of high temperature strength and low-temperature damage tolerance. Moreover this family of alloys also exhibits a high melting point and a low density; hence they are good candidates for low pressure turbine blade applications over the temperature range of 800–1000 °C. The aim of this study is to investigate the chemical composition changes, especially the O-Ti2AlNb phase precipitation and the silicon addition effects on the microstructures and high temperature mechanical properties. This study starts with a first prospective on the chemical compositions of alloys showing the highest potential for applications wanted. The studied alloys show a good balance between the ductility at room temperature induced by titanium which stopped the fragile intermetallic d-Nb3Al precipitation; and a high niobium content to maintain good high temperature mechanical properties. Two alloys are doped with 1 %at Si to improve high temperature strength and keep an acceptable ductility at room temperature. The result indicates on the more promising alloy chemical composition. We also investigate the influence of aluminum and silicon content on phase transformation. The system is reinforced by chemical ordering A2 ? B2, by solid solution or by precipitation hardening of O-Ti2AlNb. The kinetic of precipitation of this O-Ti2AlNb relied on the chemical composition. In particular, the addition of silicon enlarges the O-Ti2AlNb precipitation domain and accelerates the kinetic of precipitation.

Thermal fatigue is a serious problem in todays power plants. A large amount of damages around the world circles around that subject. The damage can come from the mechanism of two flows mixing with different temperatures in a T-junction. It is a fundamental prerequisite that these T-junctions are frequently tested for damages. An amount of criterias steers the rate of testings. This guide/document will provide the process of rating the T-junctions resistance with valid information and ease the course. If a T-junction is stated as very sensetive for thermal fatigue, it will be graded with a low damage index. This value is reliant of the temperature difference between the two flows and can be changed with different actions, for example by adding a mixer to the T-junction. The mixer will blend the two flows so the thermal fatigue reduces or doesn’t occour at all. The T-junction can be tested with several methods, ultra sonic testing or eddy-current testing. The ultra sonic testing method is the most used method and can test the inside of the T-junction pipe without access of the inside.

Ex vivo expansion of T lymphocytes is a central process in the generation of cellular therapies targeted at tumors and other disease-relevant structures,which currently cannot be reached by established pharmaceuticals. The influence of culture conditions on T cell functions is, however, incompletely understood. In clinical applications of ex vivo expanded T cells, so far, a relatively classical standard cell culture methodology has been established. The expanded cells have been characterized in both preclinical models and clinical studies mainly using a therapeutic endpoint, for example antitumor response and cytotoxic function against cellular targets, whereas the influence of manipulations of T cells ex vivo including transduction and culture expansion has been studied to a much lesser detail, or in many contexts remains unknown. This includes the circulation behavior of expanded T cells after intravenous application, their intracellular metabolism and signal transduction, and their cytoskeletal (re)organization or their adhesion, migration, and subsequent intra-tissue differentiation. This review aims to provide an overview of established T cell expansion methodologies and address unanswered questions relating in vivo interaction of ex vivo expanded T cells for cellular therapy.

Nierenzellkarzinome (NZKs) gelten als stark immunogene Tumore. Dies ist insbesondere auf die Infiltration durch verschiedene Immunzellpopulationen, wie T-Lymphozyten und Natürliche Killer (NK)-Zellen, sowie das klinische Ansprechen auf immuntherapeutische Strategien zurückzuführen. Bisher existieren jedoch nur sehr wenige Studien zur Rolle von humanen nativen dendritischen Zellen (DCs) in NZK-Geweben und über die Tumor-vermittelte Modulation dieser DCs. DCs nehmen als professionelle Antigen-präsentierende Zellen eine zentrale Schlüsselrolle bei der Induktion und Aufrechterhaltung der angeborenen sowie adaptiven Immunantwort ein. Daher wurde im Rahmen dieser Arbeit erstmals der Effekt von klarzelligen NZKs auf den Phänotyp sowie die immunmodulatorischen Fähigkeiten von 6-sulfo LacNAc+ (slan)DCs evaluiert. SlanDCs, welche eine große Subpopulation humaner Blut-DCs darstellen, sind neben der Sekretion großer Mengen proinflammatorischer Zytokine dazu befähigt, Tumorzellen direkt zu lysieren. Des Weiteren sind slanDCs in der Lage, die antitumoralen Effekte von NK-Zellen zu fördern und CD4+ T-Helfer-Zellen sowie Tumor-reaktive CD8+ T-Lymphozyten effizient zu stimulieren. Angesichts dieser proinflammatorischen Eigenschaften können slanDCs wesentlich an einer Tumor-gerichteten Immunantwort beteiligt sein. Auf dieser Grundlage erfolgte im Rahmen der vorliegenden Arbeit der immunhistochemische Nachweis von slanDCs in klarzelligen NZK-Geweben. Im Vergleich zu Tumor-freiem Nierengewebe trat in den primären Tumorgeweben eine erhöhte Zahl infiltrierender slanDCs auf. Zudem wurde die Präsenz von slanDCs in Lymphknoten- sowie Fernmetastasen von NZK-Patienten beobachtet. Weiterführende Untersuchungen an frischen klarzelligen NZK-Geweben demonstrierten, dass NZK-infiltrierende slanDCs einen unreifen Phänotyp ausprägen und Interleukin-10 produzieren. Ausgehend von diesen Erkenntnissen erfolgten funktionelle Analysen, bei denen der Einfluss der kommerziell erhältlichen klarzelligen NZK-Linien ACHN und Caki-1 sowie der primären klarzelligen NZK-Linien MZ1257RC und MZ2877RC auf bedeutende immunmodulatorische Fähigkeiten von slanDCs untersucht wurde. In diesem Zusammenhang zeigte sich, dass NZK-Zellen effektiv in der Lage sind, sowohl die slanDC-vermittelte Proliferation von CD4+ und CD8+ T-Lymphozyten, als auch die slanDC-induzierte Differenzierung naïver CD4+ T-Lymphozyten in proinflammatorische T-Helfer 1-Zellen zu inhibieren. Darüber hinaus wurde demonstriert, dass NZK-Zellen das Potenzial von slanDCs zur Aktivierung von NK-Zellen hemmen. Untersuchungen der zugrunde liegenden Mechanismen zeigten, dass die funktionelle Inhibition von slanDCs durch klarzellige NZK-Zellen über membranständige Moleküle vermittelt wird. Die im Rahmen dieser Dissertation gewonnenen Erkenntnisse weisen darauf hin, dass NZKs die Ausreifung sowie wesentliche funktionelle Eigenschaften von DCs inhibieren. Dies deutet auf einen neuen Immunescape-Mechanismus klarzelliger NZKs hin, welcher auf einer Tumorzell-vermittelten Generierung von tolerogenen slanDCs basiert und eine unzureichende Aktivierung der angeborenen sowie adaptiven Tumor-gerichteten Immunantwort zur Folge hat. Diese neuen Erkenntnisse können einen Beitrag zu einem besseren Verständnis der Interaktion von NZKs mit nativen humanen DCs leisten und die Konzeption neuer therapeutischer Strategien ermöglichen, welche auf einer Verstärkung der antitumoralen Eigenschaften von DCs beruhen.

Signalling through antigen specific receptors BCR and TCR is crucial for the development and the function of T cells and B cells. Although much is known about their signalling pathways a number of observations still remain to be clarified. In my thesis, I focused on the roles of Src-family kinases (SFKs) in the initiation of BCR- and TCR-mediated signalling. Several studies have suggested that in contrast to TCR signalling, BCR signal transduction could be initiated independently of SFKs or with only a minimal activity of these kinases. We used genetic approach to study the differences between TCR and BCR signalling apparatuses combined with inhibition of SFKs by pharmacological approach. Using this experimental set up, we show that the differences in the roles of SFKs and in the activities of SFKs needed for the initiation of BCR and TCR signalling are likely based on different composition or architecture of BCR and TCR. We further show that the SFK activity required for the initiation of TCR signalling is lower if ZAP-70 kinase is substituted with Syk kinase, which most likely reflects the different molecular mechanisms of Syk and ZAP-70 kinase activation. Key words: Src-family kinases, BCR receptor, TCR receptor, PP2, B cells, T cells, BCR signalling, TCR signalling.

O vírus Epstein-Barr infecta aproximadamente 95% da população mundial adulta, estabelecendo uma infecção latente e assintomática. Porém, é um vírus associado à neoplasias malignas, tais como carcinomas de nasofaringe, linfomas de Hodgkin, alguns casos de carcinomas gástrico, linfomas T e NK, dentre outras. O EBV também está implicado em doenças não neoplásicas como a leucoplasia pilosa. O fenômeno de imunotolerância está ligado ao potencial de infecção e oncogênico do EBV. Células dendríticas imaturas e linfócitos T reguladores são importantes nesse contexto. Em situações neoplásicas, esse mecanismo impede o reconhecimento e a destruição de células tumorais. O objetivo desse trabalho foi estudar em quatro diferentes situações de infecção pelo EBV, a saber, amigdalite crônica, linfomas de Hodgkin, leucoplasia pilosa e carcinomas de nasofaringe, a presença de células dendríticas imaturas e linfócitos T reguladores, e também o papel da citocina MIP3 no recrutamento dessas células. Foram utilizadas as técnicas de hibridização in situ para detecção do EBV e imunoistoquímica para detecção das células dendríticas, linfócitos T reg e para análise da expressão de MIP3. Em todos os casos de linfoma de Hodgkin, amigdalites e carcinomas de nasofaringe EBV+ observou-se uma forte concentração de células dendríticas imaturas e linfócitos T reg. A expressão de MIP3 mostrou-se intensa nas neoplasias EBV positivas e fraca nos casos de amigdalite crônica. Não foi observada expressão de MIP3 nos casos de leucoplasia pilosa. A concentração de células dendríticas imaturas e linfócitos T reg está intimamente ligada à presença de céulas EBV+ e pela expressão de MIP3 nos linfomas de Hodgkin associados ao EBV e carcinomas de nasofaringe, criando assim um micro-ambiente de imunossupressão nessas lesões. / The Epstein-Barr virus infects approximately 95% of adult world-wilde population, establishing a latent and asymptomatic infection. However it is related to malignant neoplasia, such as nasopharynx carcinomas, Hodgkin disease, some gastric carcinomas, T/NK lymphomas among others. EBV is also implicated in non-neoplasic disease such as hairy leukoplakia. This phenomenon is associated with the EBV infectious and oncogenic potential. Immature dendritic cells and T reg cells are important in this context. In neoplasic situations, this mechanism obstructs recognition and destruction of tumoral cells. The aim of this work was study, in four different situations of EBV infection, to knowledge, chronic tonsillitis, Hodgkins disease, hairy leukoplakia and nasopharynx carcinoma, the presence of immature dendritic cells and T reg cells, and also the role of cytokine MIP3 in the recruitment of these cells. In situ hybridization was performed for EBV detection and immunohistochemistry for dendritic cells and T reg cells detection and also for expression evaluation of MIP3 cytokine. In all the cases of Hodgkins disease, tonsillitis and nasopharynx carcinoma EBV+, a strong concentration of immature dendritic cells and T reg lymphocytes was observed. The MIP3 expression was more intense on EBV positive neoplasia and weak in cases of chronic tonsillitis. No MIP3 expression was observed in hairy leukoplakia. The concentration of immature dendritic cell and T reg lymphocyte is intimately connected with the presence of EBV positive-cells and MIP3 expression in Hodgkin disease associated to EBV and nasopharynx carcinoma, creating a microenvironment of immunosuppression in these neoplasias.