Literatura científica selecionada sobre o tema "Lymphocytes Immunological aspects"

Considering a stage of the pathological process patients (boys at the age of 8-12 years) were divided into two (2) groups. Group I included 14 patients with the fragmentation stage (Perthes disease Stage II). Group 2 included 15 children with Perthes disease Stage III (the stage of re-ossification). Perthes disease regardless of the stage of the disease was characterized by the increase in oxygen-dependent and lysosomal phagocytic activity of neutrophils, the increase in the number of early extracellular traps, as well as by increased concentrations of pro-inflammatory cytokines (IL-1β and TNFa), IgE, decreased concentrations of IL-18. The fragmentation stage was characterized by moderate activation of cellular immunity with a prevailing increase in the number of T-lymphocytes with early activation markers (CD25). At the re-ossification stage the predominance of T-lymphocytes was observed with late activation markers (HLADR), being accompanied by moderate activation of humoral immunity (increased concentrations of class A and G serum immunoglobulins). The obtained data can be used as additional criteria for clarifying Perthes disease stage, predicting osteonecrosis development when making decision of the feasibility of performing reconstructive surgeries on the joint.

The results of a comprehensive study of immune homeostasis in 45 patients with long-term insulin-dependent diabetes mellitus are presented. In 50% of the examined patients, the absolute number of leukocytes was reduced, in a third - the number of lymphocytes and the total population of T-lymphocytes, in every second patient - the number of T-helpers and in a quarter - T-suppressors, and quite significantly. In 50% of patients, a sharp decrease in the immunoregulatory index, a significant decrease in the absolute number of B-lymphocytes were found. A significant increase in the content of activated T-lymphocytes and a decrease in the number of null lymphocytes were revealed, there was a disimmunoglobulinemia. In 50% of patients, the activity of the C3 component of the complement and the level of the CEC were increased.

According to modern concept of the etiopathogenesis of essential hypertension, immune cells play an important role in its development. Mediators produced by immunocompetent cells participate in the initiation and maintenance of chronic systemic inflammation and promote the development of vascular remodeling which is an important part of the pathogenesis of the disease and target organ damage. The immune mechanisms underlying blood pressure elevation include the activation of innate and adaptive immune cells. Endothelial damage triggers an inflammatory cascade, causing migration of the immune cells to the inflammatory site, mediated by chemokines and adhesion molecules. Macrophage infiltration of perivascular tissue contributes to impaired vasodilation and damage to target organs due to the production of active forms of oxygen. Angiotensin II also causes T cell infiltration of perivascular adipose tissue and adventitia and an increased production of tumor necrosis factor alpha and interferon gamma. In addition, T lymphocytes express the mineralocorticoid receptor involved in the development of systemic hypertension. An important role in the progression of hypertension belongs to interleukin-17, which is involved in blood pressure elevation and vascular remodeling. The review also contains data on the effect of gut microbiota on the regulation of blood pressure and the development of hypertension.

Abstract. According to modern data, systemic inflammatory process with vascular endothelial dysfunction (ED) is the base of chronic obstructive pulmonary disease (COPD) pathogenesis whith chronic bronchial obstruction and the formation of comorbidity. Immunological investigations of relationship with severity of ED and risk of fatal cardiovascular events remain actual at COPD, although many studies of their dependence on the severity of COPD have been conducted. The aim of the study is to evaluate the special features of cellular immunity in patients with COPD in relation to the severity of clinical manifestations of the disease (assessed by the COPD Assessment Test –CAT), and the presence of ED. Methods. 141 patients with COPD stage II-III were examined, at the age of 43-72 years, beyond the period of exacerbation and 24 practically healthy persons as a control group for laboratory indices. Cellular immunity was studied by indirect immunofluorescence reaction using monoclonal antibodies. Dependence of cellular immunity on the value of CAT, the level of the ED laboratory marker — endothelin-1 — and the expressiveness of cardiovascular risk (CVR) were analyzed. Results. At the examined patients immune dysfunction was manifested by suppression of T-lymphocytes, disturbances in their subpopulations ratio, increased readiness of lymphocytes to apoptosis and expression of CD54+, which characterizes the adhesive properties of cells. It was also proposed to calculate the adhesion index (CD54+/CD3+), which links the elevation of the lymphocytes adhesive properties with the development of immune dysfunction. It was shown that the severity of the cellular immune system dysfunction is primarily associated with the intensity of clinical manifestations of COPD, assessed by CAT. At the same time, significantly higher endothelin-1 level in COPD patients served as an objective confirmation of ED presence. It was found that the elevation of endothelin-1 level in serum and the increasing in CVR are accompanied by an increased predisposition of lymphocytes’ apoptosis. These changes contribute to increased immune dysfunction and elevation of lymphocytes’ adhesive properties, assessed by the expression of CD54+ and indirectly confirm the participation of cellular immune mechanisms in the development of ED. Conclusions. Patients with COPD demonstrate increased expression of CD54+ on lymphocytes and elevation of the adhesion index CD54+/ CD3+. It characterizes the activation of lymphocytes adhesive properties and their increased readiness for Fas-dependent apoptosis and related immune dysfunction. These results confirm the participation of cellular immune mechanisms in the development of endothelial dysfunction. Key words: chronic bronchial obstruction, cellular immunity, endothelial dysfunction.

Common variable immunodeficiency (CVID) is an immunological disorder characterized by defective antibody production, recurrent infections, most notably of the respiratory tract, autoimmune phenomena and cancer. Some CVID patients may also present disturbances of the cellular immune response such as a decrease in the number and proportion of different lymphocyte populations, diminished lymphoproliferative response to mitogens and antigens, altered production of cytokines, and deficient expression of cell-surface molecules. Most Brazilian CVID patients included in this study show a decrease in T and B lymphocyte counts in the peripheral blood. Furthermore, their lymphocytes are more susceptible to apoptosis following activation than normal individuals, and they have a decrease in the expression of activation molecules like CD25, CD69, CD40L and CD70. Moreover, they show a decreased synthesis of IL-4 and IL-5 in comparison with normal individuals. The increase in susceptibility to apoptosis following activation, may also be responsible for the decrease in the expression of activation molecules and CD40L, decrease in Th2 cytokines synthesis, and in the number of T and B circulating cells. In this study we discuss some of these immunological disturbances correlating them to the patients' clinical features and comparing our patients' findings to the literature.

The authors analyzed the subpopulation composition of lymphocytes in the peripheral blood of 69 patients suffering from chronic recurrent furunculosis and herpes at the stage of remission. They revealed similar changes in the form of an increased content of T-helpers and immunoregulatory index. In herpes patients such changes are accompanied with the reduced number of natural killers while in furunculosis patients changes are related to the reduced amount of activated T-lymphocytes. These changes do not depend on the relapse duration or frequency but are related to the number of exacerbations in the course of the disease.

Preeclampsia (PE) is one of the most common complications of pregnancy, and it can be after 20 weeks of gestation. It ends only with a complete dissection of afterbirth. Traditionally, PE is subdivided into the early one, taking place through 34 weeks of pregnancy (EOPE) and the late one, which is after 34 weeks of gestation (LOPE). Clinical manifestations are similar in both cases however, risk factors and the severity of PE are different . It has been established that EOPE is determined by impaired trophoblast invasion and transformation of the spiral arteries of the uterus in early pregnancy, and late onset of PE is associated with oxidative stress of syncytiotrophoblast, which occurs secondarily, with limited gas exchange and insufficient intake of nutrients. Numerous studies have noted a significant contribution of immune responses to the pathogenesis of preeclampsia, however, the state of B-lymphocytes in EOPE and LOPE has not been studied. A comprehensive assessment of the condition of women with early (up to 34 weeks of pregnancy inclusive) and late (after 34 weeks) development of preeclampsia was carried out, taking into account clinical and anamnestic characteristics, the peculiarities of the formation of the structural components of the placenta, as well as determining the nature of differentiation and functional activity of B-lymphocytes. In peripheral venous blood, the content of CD19+, CD20+, CD19+CD27+IgD±, CD19+CD20- CD38+, CD20+CD5+-cells and serum levels of IL-5, IL-9, IL-13 were examined. Morphological examination included gross description, organometry, survey histology, and transmission electron microscopy. In the group of women with early preeclampsia in history, there were more often perinatal losses, premature births and medical abortions, and in the current pregnancy, intrauterine infection, oligohydramnios, placental insufficiency and fetal growth retardation. With late preeclampsia, metabolic syndrome, anemia, and a history of arterial hypertension were more often observed. In the peripheral blood of all women with preeclampsia, there was an increase in the content of CD20+CD5+-cells in comparison with those in uncomplicated pregnancy, more pronounced in the late onset of preeclampsia. Only in women with early preeclampsia blood levels of CD19+CD20- CD38+ and CD19+CD27+IgD±-cells, IL-5, IL-9 and IL-13 increased. Studies of the placenta in early preeclampsia indicated impaired implantation and pathological placentation with the development of primary placental insufficiency, which becomes chronic. In late preeclampsia, the development of placental insufficiency was determined by chronic disorders of maternal and fetal hemocirculation with increased deposition of fibrin and fibrinoid in the basal lamina and in the zones of villous epithelium necrosis. The study showed that the timing of the manifestation of preeclampsia is determined by the action of factors of the clinical history, structural rearrangements in the placenta and immune responses of B-lymphocytes are closely interrelated.

Introduction Hashimoto's thyroiditis is the most common form of acquired hypothyroidism. Fine needle aspiration cytology is one important tool in diagnosing Hashimoto's thyroditis, along with clinical, biochemical, immunological and ultrasonographical modalities. The present study examines cytological aspects of Hashimoto's thyroiditis along with their correlation with clinical, biochemical and immunological findings, whenever available. Materials and Methods This is a retrospective study of 50 cases of Hashimoto's thyroiditis. Cytological findings were reviewed and correlated with clinical, biochemical and immunological findings whenever available. Results The majority of the patients were middle-aged females, with a female to male ratio of 6.14:1. Most patients presented with diffuse thyromegaly (68%) and/or hypothyroidism (56.09%). The antibody profile was available in 22% of patients. Of these, anti-thyroid peroxidase antibodies were raised in 81.81% of patients and anti-thyroglobulin antibodies were raised in 63.63% of patients. In the present study, high lymphoid to epithelial cell ratio was seen in 78% of cases, and 74% of cases showed Hurthle cell change. Follicular atypia was seen in 36% of cases. Lymphoid follicle formation was seen in seen in 54% of cases. Follicular cell infiltration by lymphocytes, eosinophils and neutrophils was seen in 72%, 48% and 26% of cases, respectively. Plasma cells were seen in 18% of cases. Conclusion Thyroid function tests and immunological tests cannot diagnose all cases of Hashimoto's thyroiditis. Fine needle aspiration cytology continues to be a diagnostic tool of significance in diagnosing Hashimoto's thyroiditis. The presence of inflammatory cells, particularly lymphocytes and eosinophils, was detected in a significant proportion of cases.

Background. Some aspects of diagnostics and treatment of secondary pyelonephritis in children continue to be urgent tasks of pediatrics, especially with regard to immunological changes in this disease and the search for ways to optimally correct them. The purpose of the study: to study immunological disorders in children with VP and to determine the features of the use of the tablet preparation Polyoxidonium for their correction. Materials and methods. The study is an open controlled prospective comparative single-center study, including two groups: observation and control. The observation group consisted of 40 children aged 515 years (Me = 10; Q1 = 6; Q3 = 14) with secondary pyelonephritis, realized against the background of congenital urological pathology. The control group consisted of 100 practically healthy children (health groups 1 and 2) aged 5 to 17 years (Me = 10; Q1 = 7; Q3 = 14). The patients underwent a standard examination, including in-depth immunological examination. The revealed violations of immunological resistance justified the inclusion of the domestic drug Polyoxidonium in the complex therapy of patients. Results. 3 months after the treatment with the Polyoxidonium immunomodulator, an increase in the level of immunoglobulin A, the total number of lymphocytes, B cells, normalization of the number of CD19 lymphocytes, a decrease in the number of T lymphocytes and CD4 cells, an increase in phagocytosis and natural killers was noted. Conclusion. Thus, complex therapeutic tactics for children with secondary pyelonephritis should be determined taking into account individual immunological shifts, namely: a reduced number of CD19 lymphocytes and the level of immunoglobulin A, an excessively high content of helper cells, to increase phagocytosis and the number of NK lymphocytes.

[Truncated abstract] A paradox exists in tumour immunology whereby progressive tumour growth exists in parallel with an anti-tumour T cell response. This defective T cell response is thought to result from the induction of T cell tolerance and/or tumour induced immunosuppression, which act to inhibit the activation, differentiation and function of tumour-specific CD8+ T cells. Dendritic cells (DCs) are professional antigen presenting cells (APCs) that are critical to the generation of effective CTL; however their function and phenotype is often defective or altered in tumour-bearing hosts, which may limit their capacity to mount an effective tumour specific T cell response. In this thesis, the role of DCs in the cross-presentation of tumour antigen was assessed in terms of their APC function, migration and location. In doing so the intention was to gain insight into the early processes that potentially contribute to the development of an ineffective anti-tumour immune response. This study examined cross-presentation of the nominal tumour antigen, influenza A hemagglutinin (HA) expressed by the murine malignant mesothelioma cell line, AB1-HA. Cross-presentation was predominantly restricted to the local draining lymph nodes throughout tumour growth and was mediated by CD8a+ and CD8a- DCs. This results in an ineffective CTL response due to the lack of DC activation and the presence of potentially immunosuppressive B7 molecules. However, the capacity of the CD8a- DC subset to cross-present antigen suggested a role for migratory tumour-resident DCs in this process. Analysis of tumour infiltrating DCs showed that they were paralysed in their capacity to cross-present tumour antigen and were immobilised at the tumour site. Conversely, cross-presentation of tumour antigen in the local draining lymph node was dependent on the continuous traffic of antigen from the tumour microenvironment. In this vein, small numbers of metastatic tumour cells were detected in the draining lymph nodes, however their isolation was dependent on the removal of DCs and T cells, suggesting immune control of metastatic spread. Thus, tumour cells may be the source of antigen for cross-presentation by DCs in the tumour draining lymph nodes. .... In conclusion, the results presented in this thesis support a role for DCs in the generation of tumour-specific T cell responses that fail to control tumour growth. In addition the results provide a basis for further investigation into the effects of chemotherapy on the source and form of tumour antigen for cross-presentation by specific DC subsets in the tumour bearing host. These findings may have important implications for the development of future anti-cancer immune therapies targeting DCs.

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on April 1, 2010). Vita. Thesis advisor: Habib Zaghouani. "May 2008" Includes bibliographical references.

Le système immunitaire est capable de rejeter une tumeur, même si l'interaction entre système immun et tumeurs est et reste complexe. Contrôler à long terme la croissance de la tumeur est un challenge, probablement suite à divers mécanismes de tolérance centrale et périphérique. Différentes approches d'immunothérapie du cancer ont été et sont toujours développées. Nous avons, au laboratoire, investigué et démontré, dans le cadre de deux différents modèles tumoraux murins, les capacités thérapeutiques d’une nouvelle stratégie de vaccinations combinées associant des injections de cellules dendritiques (DC) et de cellules tumorales sécrétrices de GM-CSF.

Notre travail de thèse a consisté à poursuivre l'étude de cette stratégie de vaccins combinés en étudiant plus particulièrement le rôle des lymphocytes T régulateurs (Treg) dans l'efficacité thérapeutique des vaccinations.

Les Treg regroupent différentes populations cellulaires immunosuppressives dérivées du thymus qui jouent un rôle clé dans le maintien de la tolérance périphérique. Les Treg naturels dont le mécanisme de suppression principal nécessite un contact cellule-cellule, expriment de façon constitutive les molécules de surface CD4, CD25 et CTLA-4 mais le marqueur le plus spécifique est le facteur de transcription Foxp3 qui est indispensable à leur développement et à leur fonction suppressive. Dans un premier temps, nous avons donc caractérisé les Treg de rat pour l'expression de Foxp3 et la nature et spécificité antigénique de leur fonction suppressive. Nos résultats démontrent d’une part, une expression de Foxp3 restreinte aux LT CD25+ natifs et liée à une fonction suppressive s'exerçant par contact cellule-cellule et d’autre part, une spécificité antigénique non-restreinte de ces Treg.

Ensuite, nous avons utilisé ce modèle de vaccination associant des injections de DC et de cellules tumorales sécrétrices de GM-CSF pour analyser comparativement les réponses immunes induites chez les rats vaccinés guéris ou non-guéris et les rats contrôles non vaccinés et identifier les paramètres cruciaux conduisant à l'éradication de la tumeur. Nos résultats ont montré que la principale différence entre rats vaccinés guéris et non guéris ne réside pas dans l'induction de réponses cytotoxiques systémiques spécifiques de la tumeur. Par contre, la guérison est associée à la persistance d'une réponse systémique LT CD4+ TH1 ainsi qu'au recrutement important en intratumoral de LT CD8+ cytotoxiques lié à une faible proportion relative de Treg.

Comme dans la majorité des études publiées chez l'animal, les DC utilisées dans ces vaccins combinés ont été générées à partir de rats naïfs, par différenciation de précurseurs de la moëlle osseuse en présence de GM-CSF seul. Par analogie avec les vaccins DC administrés aux patients cancéreux, nous avons aussi dérivé des DC à partir de la moëlle osseuse de rats porteurs d’une tumeur (TUM+) et nous avons constaté que ces mêmes vaccins combinés montraient in vivo une efficacité thérapeutique nettement moins bonne que leurs équivalents naïfs. Nous avons établi que cette différence d’efficacité était liée à la présence de Treg fonctionnels dans les vaccins DC dérivés de rats TUM+. Puis, nous avons établi le lien entre la présence de Treg dans les vaccins DC TUM+ et leur moins bonne efficacité thérapeutique en montrant qu'un traitement in vivo des rats TUM+ au témozolomide (TMZ) avant de générer les vaccins DC résultait in vitro, en une moindre expression de Foxp3 et une fonction suppressive diminuée et in vivo, en une bien meilleure survie des rats vaccinés.

Enfin, dans le but d’une utilisation future en clinique, nous avons développé une approche simplifiée ‘tout in vivo’ de notre modèle de vaccinations combinées, en utilisant la tumeur localement irradiée in vivo comme source d’antigène pour des DC autologues injectées en péri-tumoral et un apport exogène de GM-CSF. Nous avons utilisé des adénovirus associés recombinants porteurs du gène du GM-CSF (AAV1-GM-CSF) pour transduire la tumeur in vivo. Ces injections intratumorales d’AAV1-GM-CSF ont montré de bons résultats en vaccinations combinées puisque 60% des rats ont pu être guéris d’une tumeur 9L pré-implantée. Nous avons ensuite expérimenté l’enrobage des AAV1-GM-CSF dans un polymère biocompatible et thermosensible, le poloxamère, avant de les injecter en intratumoral, sans observer de meilleur effet thérapeutique. Cependant, nous avons constaté que l'utilisation du poloxamère pour enrober du GM-CSF recombinant permettait d'améliorer nettement la survie des rats vaccinés par comparaison à l'utilisation de GM-CSF recombinant seul.

La stratégie de vaccinations combinées que nous avons largement explorée et validée chez le rat serait une alternative intéressante à développer en clinique, particulièrement en combinaison avec un traitement permettant d'éliminer les Treg à la fois dans les vaccins et chez les patients vaccinés.

Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished

L'infection par le cytomégalovirus humain (HCMV) est une cause majeure de mortalité chez les patients immunodéprimés et représente la première cause d'infection congénitale. HCMV est un virus complexe qui s'est adapté au système immunitaire humain en développant de multiples mécanismes d'évasion. L'infection primaire à HCMV est associée à une réplication virale prolongée avant l'établissement de la latence. Il a été montré que cette intense réplication lors de la phase initiale de l'infection était associée à une épuisement fonctionnel des lymphocytes T CD4 spécifiques du virus. Alors que les anticorps jouent un rôle dans la limitation de la dissémination virale et la prévention de l'infection à HCMV, les réponses des lymphocytes B sont peu caractérisées. Dans le présent travail, nous avons étudié l'impact de l'infection à HCMV sur le phénotype et la fonctionnalité des sous-populations de LB du sang circulant chez une cohorte de femme enceintes avec une primo-infection par HCMV en utilisant comme contrôles des sujets sains séropositifs et séronégatifs pour HCMV ainsi que des femmes enceintes séronégatives. Nous montrons que l'infection primaire par HCMV induit une expansion significative et prolongée de deux sous-populations de LB :les LB mémoires activés (CD27+CD21low) et mémoires atypiques (CD27-CD21low), précédemment décrites lors d'infection chroniques. Les LB mémoires atypiques démontrent des signes d'épuisement fonctionnel comme en témoigne une expression élevée de récepteurs inhibant le BCR et une moindre réponse à la stimulation in vitro mesurée par la production de TNF-α. Les expansions de ces deux sous-populations sont corrélées entre elles et liées à la virémie. Ces résultats contribuent à la compréhension de la régulation des réponses des LB lors d'infections virales, en montrant que l'épuisement fonctionnel de LB, précédemment décrit lors d'infections chroniques, peut également survenir lors d'infections primaires.

Dans un deuxième temps, nous avons étudié l'acquisition des réponses B mémoires spécifiques de HCMV dirigées contre la principale glycoprotéine de surface, la glycoprotéine B (gB), et deux polypeptides du tégument. Lors de l'infection primaire par HCMV, la production d'anticorps neutralisant le virus, dirigés contre les glycoprotéines d'enveloppe, est retardée par rapport aux anticorps dirigés contre le tégument qui sont non neutralisant. Nous montrons que le phénotype des LB mémoires spécifiques de gB est différent de celui des LB mémoires spécifiques du tégument. La majorité des LB mémoires spécifiques de gB exprime un phénotype CD27+CD21+ alors que la majorité de ceux du tégument exprime le phénotype CD27+CD21low. Nous montrons par la suite chez des sujets sains que ces deux sous-populations de LB mémoires présentent des différences phénotypiques, au niveau de l'expression de récepteurs liés au "trafficking" cellulaire ainsi qu'au niveau de la fonctionnalité. Les LB mémoires CD21low, contrairement au LB mémoires CD21high, expriment des taux bas des récepteurs CXCR5 et CCR7, qui permettent la migration vers les centres germinatifs, mais des taux élevés de CD11c promouvant la migration vers les tissus périphériques. Après stimulation in vitro, les LB mémoires CD21low vont avoir une capacité de production d'immunoglobulines immédiate mais une réponse proliférative plus faible comparée aux LB mémoires CD21+. Nous démontrons la relevance de cette division des LB mémoires sur base de l'expression du CD21 dans un modèle de vaccination de rappel contre la toxoïde tétanique (TT). Après rappel, nous observons une expansion significative de LB mémoires spécifiques de la TT exprimant un phénotype CD27+CD21lowCXCR5lowCD11chigh. Nous proposons ainsi un nouveau mécanisme de manipulation des réponses humorales par des pathogènes qui se traduit par une limitation de l'induction de réponses B effectrices. Nos travaux permettraient également une meilleure approche des réponses B mémoires physiologiques chez l'homme en proposant une classification des LB mémoires basées sur leur fonctionnalité et leur phénotype.

Human cytomegalovirus (HCMV) infection is a major cause of mortality in immunocompromised patients and is the first cause of congenital infection worldwide. HCMV is a complex virus that has developed multiples immune evasions mechanisms during its co-evolution with mankind. Although often asymptomatic, primary HCMV infection is associated with an intense and prolonged viral replication. It has been previously shown that this intense viral replication is associated with functional exhaustion of virus-specific CD4+ T cells. Although neutralizing antibodies limits viral dissemination and play a role in the prevention of HCMV infection, B cell responses during HCMV infection have been poorly studied so far.

In this work, we have studied the impact of HCMV infection on the phenotype and functionality of peripheral-blood B cell subsets in a cohort of pregnant women with a primary HCMV infection. Controls were healthy seronegative and seropositive HCMV donors and HCMV seronegative pregnant women. We show that primary HCMV infection induces a significant and prolonged expansion of two B-cell subsets, previously described in chronic infections :activated memory B cells (MBC) (CD27+CD21low) and atypical MBC (CD27-CD21low). Atypical MBC display signs of functional exhaustion with increased expression of inhibitory receptors and a lower response to in vitro stimulation as assessed by TNF-α production. Expansion of these two subsets are correlated and higher in subjects with detectable viremia. These results contribute to the understanding of the regulation of B cell responses during viral infections and indicate that B cell exhaustion, previously described during chronic infections, can be observed in primary infection.

Next, we have characterized the acquisition of HCMV-specific B cell responses directed against envelope glycoprotein B (gB) and two tegument polypeptides (pp150 and pp52). During primary HCMV infection, the production of neutralizing antibodies targeting envelope glycoproteins is delayed when compared to non-neutralizing anti-tegument antibodies. We show that gB and tegument-specific MBC have distinct phenotype during primary HCMV infection. The majority of gB-specific MBC have a CD27+CD21+ phenotype while the majority of tegument-specific MBC have a CD27+CD21low phenotype. We show that CD27+CD21+ and CD27+CD21low MBC express different pattern of chemokine receptors pattern but also have distinct functionality. CD27+CD21low MBC, on the contrary to CD27+CD21+ MBC, express low levels of CXCR5 and CCR7 that favor migration to lymph nodes and germinal centers but express high levels of CD11c that promotes migration to inflammatory tissues.

In vitro stimulation of sorted subsets of healthy individuals indicates that CD27+CD21low MBC have higher capacity of immediate immunoglobulin production but a lower proliferative potential as compared to CD27+CD21+ MBC. We further show the relevance of a division of MBC subsets based on CD21 expression in a model of TT booster immunization. Following booster immunization, a significant expansion of TT-specific MBC expressing the phenotype CD27+CD21lowCXCR5lowCD11chigh is observed.

We propose that HCMV manipulates the host humoral response by limiting the induction of gB-specific CD27+CD21low "effector" MBC. Our work also indicates that human MBC physiological responses should be studied according to their respective phenotype and functions.

Doctorat en Sciences médicales
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