Proefschrift Universiteit van Amsterdam. / Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

Proefschrift Universiteit van Amsterdam. / Auteursnaam op omslag: Kiki Tesselaar. Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

Thèse (Ph. D.)--Université Laval, 2007. / Titre de l'écran-titre (visionné le 5 mai 2008). Bibliogr.

L’immunité humorale, que les lymphocytes B chapeautent via la production d’anticorps, fournit à l’organisme des armes solubles et spécifiques permettant de combattre une infection en cours, et d’en conserver une mémoire immunologique. Traditionnellement, on associe la réponse des lymphocytes B naïfs à la première apparition d’un antigène et celle des cellules mémoires à l’apparition subséquente d’un antigène déjà rencontré. Ces deux sous-populations, pouvant être distinguées par l’expression différentielle de la molécule CD27, circulent simultanément en périphérie chez l’humain. Au cours de ce projet de doctorat, la réponse in vitro des lymphocytes B naïfs (CD27) et mémoires (CD27+) isolés du sang a été étudiée, dans un système exploitant l’interaction CD40-CD154, normalement médiée par les lymphocytes T, en présence de facteurs solubles. Cette étude a mis en évidence la réponse distincte des cellules naïves et mémoires lorsque stimulées séparément, reflétant la disparité de leurs besoins. La comparaison de leur stimulation simultanée ou séparée a mis au jour une possible interaction entre les cellules B naïves et mémoires, suggérant une vision nouvelle de l’initiation de la réponse primaire in vivo. De plus, cette étude a permis l’identification d’une sous-population de cellules mémoires distinctes en périphérie, au phénotype CD27-IgG+, remettant en question l’utilisation du CD27 comme marqueur de cellules B mémoires chez l’humain. La comparaison des populations stimulées suggère qu’un rôle régulateur pourrait être associé à ces cellules mémoires, pouvant contribuer à contenir la réponse des cellules naïves une fois l’infection prise en charge. En bout de ligne, ce projet a permis de modéliser la réponse humorale primaire et secondaire en tenant compte de cette nouvelle sous-population mémoire, ainsi que des interactions entre cellules B pouvant intervenir in vivo. / Humoral immunity, managed by B lymphocytes and their antibody production, provides to the body soluble and specific weapons to clear current infections and to preserve an immunological memory. Traditionally, naive B cell response is associated with the first encounter with an antigen, while memory cell response is related to its subsequent appearance. Both populations, circulating in human peripheral blood, can be distinguished by the differential expression of the CD27 molecule. During this project, the in vitro response of peripheral naive (CD27) and memory B cells (CD27+) was studied, in a system exploiting CD40-CD154 interaction, normally provided by T cells, in the presence of soluble factors. This study highlighted a distinct response from naive and memory cells when separately stimulated, reflecting their different requirements. Comparison between their stimulation, together and separately, also underlined possible B-B cell interactions, suggesting a new vision of primary response initiation in vivo. Furthermore, this study conducted to the identification of a distinct memory cell subset in periphery, displaying a CD27IgG+ phenotype, which questions the use of CD27 as a memory B cell marker in humans. A potential regulatory role has also been suggested for the CD27-IgG+ memory subset, presumably aimed to suppress naive cell response once the infection is controlled. Overall, this project supports the elaboration of a model for primary and secondary humoral responses, taking into account the new memory subset identified and the interactions among B cells that likely occur in vivo.

A imunodeficiência comum variável (ICV) é uma imunodeficiência primária de origem heterogênea, definida como uma diminuição de pelo menos dois isótipos de imunoglobulinas, a falta de resposta anticórpica a imunizações e a exclusão de outras causas primárias de hipogamaglobulinemia. A ausência de níveis adequados de anticorpos em pacientes com ICV resulta em infecções bacterianas recorrentes, mais freqüentes no trato respiratório e digestivo, que podem levar a seqüelas sinusais e pulmonares. Nos últimos 6 anos iniciou-se a descoberta de genes relacionados à causa de doenças com o fenótipo de ICV, como os genes de TACI, BAFF-R, CD19 e ICOS. Dentre as alterações imunológicas, podemos também relatar deficiência de células B de memória (CD19+IgM-IgD-CD27+), levando a distúrbio de comutação isotípica e redução da secreção de imunoglobulinas. Atualmente tal característica vem sendo utilizada para classificar a ICV. No decorrer do presente trabalho pudemos observar que pacientes com ICV apresentam alterações na expressão de CD27 não somente em células B, mas também em células T, além de resposta linfoproliferativa ao estímulo de PHA reduzida. O CD27 consiste em uma molécula da família TNF presente constitutivamente em células T e após ativação em células B. Sua atuação na resposta imune está relacionada com a proliferação e co-ativação de células T específicas que atuam na interação T-B, na resposta de células B dependente de T. Dessa forma deficiências na via de CD27 podem resultar em defeitos nos mecanismos de comutação isotípica e de diferenciação de células B do centro germinativo, assim como de células de memória. Essas características podem ser observadas em modelos murinos de deficiências de CD27/CD70. Nossos achados permitem que uma nova janela se abra para o estudo da ICV. A avaliação dos distúrbios associados a defeitos de sinalização de CD27/CD70 em humanos pode se tornar uma nova ferramenta para a compreensão de uma deficiência tão pouco esclarecida. Tal enfoque pode eventualmente contribuir para o desenvolvimento de novos tratamentos, atuando diretamente na molécula em questão. Além disso, sugerimos também a utilização da fenotipagem das moléculas CD27 em linfócitos B e T, além da IgM e IgD de membrana para a caracterização da ICV, mais a análise da molécula CD154 para exclusão de outras imunodeficiências / Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder of heterogeneous origin, defined by a decrease of at least two immunoglobulin isotypes, lack of antibody response to immunization and the exclusion of other causes of primary hypogammaglobulinemia. The absence of adequate levels of antibodies in patients with CVID results in recurrent bacterial infections, most frequently in the respiratory and digestive tract, which can lead to sinusal and lung sequels. Over the past six years the discovery of genes related to the phenotype of CVID began, such as the genes of TACI, BAFF-R, CD19 and ICOS. Among the immunological changes, there is impairment of memory B cells (CD19+/IgM-IgD-CD27+), leading to disturbance of isotypic switching and reduced secretion of immunogobulins. Currently this feature has been used to classify CVID. During the present study we observed that patients with CVID present changes in the expression of CD27 not only in B cells, but also in T cells, and reduced lymphoproliferative response to PHA. CD27 molecule is a member of the TNF family present constitutively in T cells, and after activation in B cells. Its importance in the immune response is related to the proliferation and co-activation of specific T cells that act in T-B interaction, in the T cell dependent B cells response. Thus disturbances in the CD27 pathway can result in defects in isotypic switch and differentiation of germinal center B cells, as well as memory cells. These characteristics can be observed in murine models of CD27/CD70 deficiency. Our findings allow a new approach for the study of CVID. The evaluation of defects in CD27/CD70 signaling in humans might become a new tool for understanding an incompletely understood disease. Such an approach may contribute to the development of new treatments, acting directly on the molecule in question. In addition, we also suggest the use of phenotyping of CD27 molecules on B and T lymphocytes, in addition to membrane IgM and IgD to characterize CVID, associated to the analysis of the molecule CD154 to exclude other immunodeficiencies

A imunodeficiência comum variável (ICV) é uma imunodeficiência primária de origem heterogênea, definida como uma diminuição de pelo menos dois isótipos de imunoglobulinas, a falta de resposta anticórpica a imunizações e a exclusão de outras causas primárias de hipogamaglobulinemia. A ausência de níveis adequados de anticorpos em pacientes com ICV resulta em infecções bacterianas recorrentes, mais freqüentes no trato respiratório e digestivo, que podem levar a seqüelas sinusais e pulmonares. Nos últimos 6 anos iniciou-se a descoberta de genes relacionados à causa de doenças com o fenótipo de ICV, como os genes de TACI, BAFF-R, CD19 e ICOS. Dentre as alterações imunológicas, podemos também relatar deficiência de células B de memória (CD19+IgM-IgD-CD27+), levando a distúrbio de comutação isotípica e redução da secreção de imunoglobulinas. Atualmente tal característica vem sendo utilizada para classificar a ICV. No decorrer do presente trabalho pudemos observar que pacientes com ICV apresentam alterações na expressão de CD27 não somente em células B, mas também em células T, além de resposta linfoproliferativa ao estímulo de PHA reduzida. O CD27 consiste em uma molécula da família TNF presente constitutivamente em células T e após ativação em células B. Sua atuação na resposta imune está relacionada com a proliferação e co-ativação de células T específicas que atuam na interação T-B, na resposta de células B dependente de T. Dessa forma deficiências na via de CD27 podem resultar em defeitos nos mecanismos de comutação isotípica e de diferenciação de células B do centro germinativo, assim como de células de memória. Essas características podem ser observadas em modelos murinos de deficiências de CD27/CD70. Nossos achados permitem que uma nova janela se abra para o estudo da ICV. A avaliação dos distúrbios associados a defeitos de sinalização de CD27/CD70 em humanos pode se tornar uma nova ferramenta para a compreensão de uma deficiência tão pouco esclarecida. Tal enfoque pode eventualmente contribuir para o desenvolvimento de novos tratamentos, atuando diretamente na molécula em questão. Além disso, sugerimos também a utilização da fenotipagem das moléculas CD27 em linfócitos B e T, além da IgM e IgD de membrana para a caracterização da ICV, mais a análise da molécula CD154 para exclusão de outras imunodeficiências / Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder of heterogeneous origin, defined by a decrease of at least two immunoglobulin isotypes, lack of antibody response to immunization and the exclusion of other causes of primary hypogammaglobulinemia. The absence of adequate levels of antibodies in patients with CVID results in recurrent bacterial infections, most frequently in the respiratory and digestive tract, which can lead to sinusal and lung sequels. Over the past six years the discovery of genes related to the phenotype of CVID began, such as the genes of TACI, BAFF-R, CD19 and ICOS. Among the immunological changes, there is impairment of memory B cells (CD19+/IgM-IgD-CD27+), leading to disturbance of isotypic switching and reduced secretion of immunogobulins. Currently this feature has been used to classify CVID. During the present study we observed that patients with CVID present changes in the expression of CD27 not only in B cells, but also in T cells, and reduced lymphoproliferative response to PHA. CD27 molecule is a member of the TNF family present constitutively in T cells, and after activation in B cells. Its importance in the immune response is related to the proliferation and co-activation of specific T cells that act in T-B interaction, in the T cell dependent B cells response. Thus disturbances in the CD27 pathway can result in defects in isotypic switch and differentiation of germinal center B cells, as well as memory cells. These characteristics can be observed in murine models of CD27/CD70 deficiency. Our findings allow a new approach for the study of CVID. The evaluation of defects in CD27/CD70 signaling in humans might become a new tool for understanding an incompletely understood disease. Such an approach may contribute to the development of new treatments, acting directly on the molecule in question. In addition, we also suggest the use of phenotyping of CD27 molecules on B and T lymphocytes, in addition to membrane IgM and IgD to characterize CVID, associated to the analysis of the molecule CD154 to exclude other immunodeficiencies

Chronic Lymphocytic Leukemia (CLL) is a type of cancer that affects the B cells of the immune system causing problems in the process of producing antibodies. It can be sorted into mutated and unmutated CLL based on the percentage of somatic mutations in the Immunoglobulin Heavy chain Variable region (IgHV). The B cells of healthy individuals can be sorted into three groups; CD27dull memory B cells (MBCs), CD27bright MBCs and naïve B cells. The hypothesis for the project was that the unmutated CLL subset originates from CD27dull MBCs and the mutated CLL subset originates from CD27bright MBCs. RNA-sequencing data from healthy individuals were acquired from a collaboration partner in Rome and CLL-patients were collected from public datasets available online. Several bioinformatic tools were used to analyze the data. First, the quality of the data files was checked, then adapter sequence from the sequencing process and low-quality bases were removed (trimming). Good quality of the files was confirmed after the trimming. Secondly, these files were mapped against the human reference genome (GRCh38/hg38) for alignment, then the resulted data was used to check for genes that showed differential expression between the different groups. Results were analyzed and visualized using Venn diagrams, Principal Component Analysis (PCA) and heatmap plots and random forest. A list of 85 genes was generated based on the different comparisons and was used in one PCA plot that showed clear separation between the different groups. The SWAP70 gene was analyzed for single nucleotide polymorphisms (SNPs). The study concluded five genes that could be used as biomarkers for CLL and the diagnosis of its subtypes where some of them were discussed in previous studies. Also, the mutated CLL subset showed a similar behavior to the healthy individuals and this could validate the original hypothesis and justifies the better disease prognosis for this subtype.

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Vita. Bibliography: 171-196.

Background: The presence of B cells in early stage non-small cell lung cancer (NSCLC) is associated with longer survival, however, the role these cells play in the generation and maintenance of anti-tumor immunity is unclear. B cells differentiate into a variety of subsets with differing characteristics and functions. To date, there is limited information on the specific B cell subsets found within NSCLC. To better understand the composition of the B cell populations found in NSCLC we have begun characterizing B cells in lung tumors and have detected a population of B cells that are CD79A(+)CD27(-)IgD(-). These CD27(-)IgD(-)(double-negative) B cells have previously been characterized as unconventional memory B cells and have been detected in some autoimmune diseases and in the elderly population but have not been detected previously in tumor tissue. Methods: A total of 15 fresh untreated NSCLC tumors and 15 matched adjacent lung control tissues were dissociated and analyzed by intracellular flow cytometry to detect the B cell-related markers CD79A, CD27 and IgD. All CD79A(+) B cells subsets were classified as either naive (CD27(-)IgD(+)), affinity-matured (CD27(+)IgD(-)), early memory/germinal center cells (CD27(+)IgD(+)) or double-negative B cells (CD27(-)IgD(-)). Association of double-negative B cells with clinical data including gender, age, smoking status, tumor diagnosis and pathologic differentiation status were also examined using the logistic regression analysis for age and student's t-test for all other variables. Associations with other B cell subpopulations were examined using Spearman's rank correlation. Results: We observed that double-negative B cells were frequently abundant in lung tumors compared to normal adjacent controls (13 out of 15 cases), and in some cases made up a substantial proportion of the total B cell compartment. The presence of double-negative cells was also found to be inversely related to the presence of affinity-matured B cells within the tumor, Spearman's coefficient of -0.76. Conclusions: This study is the first to observe the presence of CD27(-)IgD(-)double-negative B cells in human NSCLC and that this population is inversely correlated with traditional affinity-matured B cell populations.