B-stroma interactions in follicular lymphoma, a question led by concepts of tumor and microenvironmental heterogeneity

Le lymphome folliculaire est l'un des exemples paradigmatiques des cancers dépendant d'un microenvironnement tumoral spécifique. Il comprend notamment des fibroblastes associés au cancer (CAF) émergeant de la reprogrammation des cellules stromales lymphoïdes ou de leur(s) précurseur(s) dans le ganglion et la moelle. Les cellules stromales dans le lymphome folliculaire soutiennent directement la croissance des cellules B malignes et orchestrent la niche tumorale en contribuant, par un dialogue bidirectionnel, au recrutement et à la polarisation d'autres sous-populations immunitaires. Une meilleure compréhension des voies de signalisation et des mécanismes moléculaires responsables du remodelage des cellules stromales et de la cinétique de ce dernier seraient utiles pour définir de nouveaux marqueurs prédictifs et de nouvelles approches thérapeutiques dans ce cancer encore incurable. Les modèles in vitro récapitulant les forces biomécaniques, le microenvironnement cellulaire et l'organisation spatiale des lymphomes B restent rares, alors que tous ces paramètres constituent des éléments clés déterminants dans la lymphomagenèse et la résistance aux médicaments. En utilisant une méthode microfluidique basée sur l'encapsulation de cellules dans des microsphères d'alginate perméables, nous avons développé un nouveau modèle 3D incorporant des cellules B de lymphome, de la matrice extracellulaire et/ou des cellules stromales d’amygdale. Nous avons montré que les cellules de lymphome B étaient capables de former des sphéroïdes cohésifs résultant de la surexpression des composants de la matrice extra-cellulaire. De plus, dans ce modèle, les cellules stromales s’auto-organisent pour initier la prolifération des cellules tumorales. La culture 3D induit une résistance à l'agent chimiothérapeutique classique doxorubicine, mais pas à l'inhibiteur de BCL2 ABT-199, identifiant cette approche comme un modèle in vitro pertinent pour comprendre l’activité des agents thérapeutiques . L'analyse RNAseq a mis en évidence des modulations des voies de signalisation similaires à celles observées dans les cellules primaires de lymphome folliculaire. Enfin, notre modèle a permis la survie à long terme in vitro de cellules B primaires de lymphome folliculaire. Nous proposons ainsi un nouveau modèle 3D imitant la niche tumorale du lymphome et permettant d'étudier la relation dynamique entre les cellules tumorales et leur microenvironnement pour les tests de nouveaux médicaments anticancéreux. En parallèle, nous avons pour la première fois, initié la caractérisation d’une niche tumorale jusqu’alors jamais explorée dans le lymphome folliculaire, située dans le tissu adipeux péri-ganglionnaire. Dans cette niche, les cellules tumorales évoluent au contact de cellules stromales adoptant un phénotype CAF associé aux tumeurs solides, et de macrophages associés aux tumeurs de phénotype M2.Follicular lymphoma is the most prototypical B-cell lymphoma that depends on a specific tumor microenvironment, including cancer-associated fibroblasts (CAFs) arising from the reprogramming of lymphoid stromal cells or their precursors in the lymph node and bone marrow. Stromal cells in follicular lymphoma directly support the growth of malignant B cells and orchestrate the tumor niche by contributing, through a bidirectional dialogue, to the recruitment and polarization of other immune subpopulations. A better understanding of the signaling pathways, molecular mechanisms and kinetics of stromal cell remodeling would be instrumental in defining new predictive markers and therapeutic approaches in this still lethal malignancy. In vitro models capturing the biomechanical forces, cellular microenvironment and spatial organization of B-cell lymphomas remain scarce, while all these parameters are key determinants of lymphomagenesis and drug resistance. Using a microfluidic method based on cell encapsulation in permeable alginate beads, we developed a new 3D model incorporating lymphoma B cells, extracellular matrix and/or tonsil stromal cells. We showed that B-cells were able to form cohesive spheroids resulting from the overexpression of extracellular matrix components. Furthermore, in this model, stromal cells self-organize to initiate tumor cell proliferation. The 3D-culture induced resistance to the classical chemotherapeutic agent doxorubicin, but not to the BCL2 inhibitor ABT-199, identifying this approach as a relevant in vitro model to evaluate the activity of some? therapeutic agents. RNAseq analysis revealed modulations of signaling pathways similar to those observed in primary follicular lymphoma cells. Finally, our model supported long-term survival of primary follicular lymphoma B cells. We thus propose a new 3D-model mimicking the lymphoma tumor niche and allowing for the study of the dynamic relationship between tumor cells and their microenvironment and the testing of new anticancer drugs. In parallel, we have for the first time initiated the characterization of a tumor niche never explored before in follicular lymphoma, located in the peri-nodular adipose tissue. In this niche, tumor cells evolve in close contact with stromal cells adopting a CAF phenotype associated with solid tumors, and macrophages presenting with M2 phenotype. Also, T cells expressed an immunosuppressive signature and tumor cells adopt there a quiescent metabolic profile and a plasma cell differentiation

Interactions des cellules tumorales B et des cellules stromales dans le lymphome folliculaire : une question menée par des concepts d'hétérogénéité tumorale et micro environnementale

Follicular lymphoma is the most prototypical B-cell lymphoma that depends on a specific tumor microenvironment, including cancer-associated fibroblasts (CAFs) arising from the reprogramming of lymphoid stromal cells or their precursors in the lymph node and bone marrow. Stromal cells in follicular lymphoma directly support the growth of malignant B cells and orchestrate the tumor niche by contributing, through a bidirectional dialogue, to the recruitment and polarization of other immune subpopulations. A better understanding of the signaling pathways, molecular mechanisms and kinetics of stromal cell remodeling would be instrumental in defining new predictive markers and therapeutic approaches in this still lethal malignancy. In vitro models capturing the biomechanical forces, cellular microenvironment and spatial organization of B-cell lymphomas remain scarce, while all these parameters are key determinants of lymphomagenesis and drug resistance. Using a microfluidic method based on cell encapsulation in permeable alginate beads, we developed a new 3D model incorporating lymphoma B cells, extracellular matrix and/or tonsil stromal cells. We showed that B-cells were able to form cohesive spheroids resulting from the overexpression of extracellular matrix components. Furthermore, in this model, stromal cells self-organize to initiate tumor cell proliferation. The 3D-culture induced resistance to the classical chemotherapeutic agent doxorubicin, but not to the BCL2 inhibitor ABT-199, identifying this approach as a relevant in vitro model to evaluate the activity of some? therapeutic agents. RNAseq analysis revealed modulations of signaling pathways similar to those observed in primary follicular lymphoma cells. Finally, our model supported long-term survival of primary follicular lymphoma B cells. We thus propose a new 3D-model mimicking the lymphoma tumor niche and allowing for the study of the dynamic relationship between tumor cells and their microenvironment and the testing of new anticancer drugs. In parallel, we have for the first time initiated the characterization of a tumor niche never explored before in follicular lymphoma, located in the peri-nodular adipose tissue. In this niche, tumor cells evolve in close contact with stromal cells adopting a CAF phenotype associated with solid tumors, and macrophages presenting with M2 phenotype. Also, T cells expressed an immunosuppressive signature and tumor cells adopt there a quiescent metabolic profile and a plasma cell differentiation.Le lymphome folliculaire est l'un des exemples paradigmatiques des cancers dépendant d'un microenvironnement tumoral spécifique. Il comprend notamment des fibroblastes associés au cancer (CAF) émergeant de la reprogrammation des cellules stromales lymphoïdes ou de leur(s) précurseur(s) dans le ganglion et la moelle. Les cellules stromales dans le lymphome folliculaire soutiennent directement la croissance des cellules B malignes et orchestrent la niche tumorale en contribuant, par un dialogue bidirectionnel, au recrutement et à la polarisation d'autres sous-populations immunitaires. Une meilleure compréhension des voies de signalisation et des mécanismes moléculaires responsables du remodelage des cellules stromales et de la cinétique de ce dernier seraient utiles pour définir de nouveaux marqueurs prédictifs et de nouvelles approches thérapeutiques dans ce cancer encore incurable. Les modèles in vitro récapitulant les forces biomécaniques, le microenvironnement cellulaire et l'organisation spatiale des lymphomes B restent rares, alors que tous ces paramètres constituent des éléments clés déterminants dans la lymphomagenèse et la résistance aux médicaments. En utilisant une méthode microfluidique basée sur l'encapsulation de cellules dans des microsphères d'alginate perméables, nous avons développé un nouveau modèle 3D incorporant des cellules B de lymphome, de la matrice extracellulaire et/ou des cellules stromales d’amygdale. Nous avons montré que les cellules de lymphome B étaient capables de former des sphéroïdes cohésifs résultant de la surexpression des composants de la matrice extra-cellulaire. De plus, dans ce modèle, les cellules stromales s’auto-organisent pour initier la prolifération des cellules tumorales. La culture 3D induit une résistance à l'agent chimiothérapeutique classique doxorubicine, mais pas à l'inhibiteur de BCL2 ABT-199, identifiant cette approche comme un modèle in vitro pertinent pour comprendre l’activité des agents thérapeutiques . L'analyse RNAseq a mis en évidence des modulations des voies de signalisation similaires à celles observées dans les cellules primaires de lymphome folliculaire. Enfin, notre modèle a permis la survie à long terme in vitro de cellules B primaires de lymphome folliculaire. Nous proposons ainsi un nouveau modèle 3D imitant la niche tumorale du lymphome et permettant d'étudier la relation dynamique entre les cellules tumorales et leur microenvironnement pour les tests de nouveaux médicaments anticancéreux. En parallèle, nous avons pour la première fois, initié la caractérisation d’une niche tumorale jusqu’alors jamais explorée dans le lymphome folliculaire, située dans le tissu adipeux péri-ganglionnaire. Dans cette niche, les cellules tumorales évoluent au contact de cellules stromales adoptant un phénotype CAF associé aux tumeurs solides, et de macrophages associés aux tumeurs de phénotype M2

Interactions des cellules tumorales B et des cellules stromales dans le lymphome folliculaire : une question menée par des concepts d'hétérogénéité tumorale et micro environnementale

Follicular lymphoma is the most prototypical B-cell lymphoma that depends on a specific tumor microenvironment, including cancer-associated fibroblasts (CAFs) arising from the reprogramming of lymphoid stromal cells or their precursors in the lymph node and bone marrow. Stromal cells in follicular lymphoma directly support the growth of malignant B cells and orchestrate the tumor niche by contributing, through a bidirectional dialogue, to the recruitment and polarization of other immune subpopulations. A better understanding of the signaling pathways, molecular mechanisms and kinetics of stromal cell remodeling would be instrumental in defining new predictive markers and therapeutic approaches in this still lethal malignancy. In vitro models capturing the biomechanical forces, cellular microenvironment and spatial organization of B-cell lymphomas remain scarce, while all these parameters are key determinants of lymphomagenesis and drug resistance. Using a microfluidic method based on cell encapsulation in permeable alginate beads, we developed a new 3D model incorporating lymphoma B cells, extracellular matrix and/or tonsil stromal cells. We showed that B-cells were able to form cohesive spheroids resulting from the overexpression of extracellular matrix components. Furthermore, in this model, stromal cells self-organize to initiate tumor cell proliferation. The 3D-culture induced resistance to the classical chemotherapeutic agent doxorubicin, but not to the BCL2 inhibitor ABT-199, identifying this approach as a relevant in vitro model to evaluate the activity of some? therapeutic agents. RNAseq analysis revealed modulations of signaling pathways similar to those observed in primary follicular lymphoma cells. Finally, our model supported long-term survival of primary follicular lymphoma B cells. We thus propose a new 3D-model mimicking the lymphoma tumor niche and allowing for the study of the dynamic relationship between tumor cells and their microenvironment and the testing of new anticancer drugs. In parallel, we have for the first time initiated the characterization of a tumor niche never explored before in follicular lymphoma, located in the peri-nodular adipose tissue. In this niche, tumor cells evolve in close contact with stromal cells adopting a CAF phenotype associated with solid tumors, and macrophages presenting with M2 phenotype. Also, T cells expressed an immunosuppressive signature and tumor cells adopt there a quiescent metabolic profile and a plasma cell differentiation.Le lymphome folliculaire est l'un des exemples paradigmatiques des cancers dépendant d'un microenvironnement tumoral spécifique. Il comprend notamment des fibroblastes associés au cancer (CAF) émergeant de la reprogrammation des cellules stromales lymphoïdes ou de leur(s) précurseur(s) dans le ganglion et la moelle. Les cellules stromales dans le lymphome folliculaire soutiennent directement la croissance des cellules B malignes et orchestrent la niche tumorale en contribuant, par un dialogue bidirectionnel, au recrutement et à la polarisation d'autres sous-populations immunitaires. Une meilleure compréhension des voies de signalisation et des mécanismes moléculaires responsables du remodelage des cellules stromales et de la cinétique de ce dernier seraient utiles pour définir de nouveaux marqueurs prédictifs et de nouvelles approches thérapeutiques dans ce cancer encore incurable. Les modèles in vitro récapitulant les forces biomécaniques, le microenvironnement cellulaire et l'organisation spatiale des lymphomes B restent rares, alors que tous ces paramètres constituent des éléments clés déterminants dans la lymphomagenèse et la résistance aux médicaments. En utilisant une méthode microfluidique basée sur l'encapsulation de cellules dans des microsphères d'alginate perméables, nous avons développé un nouveau modèle 3D incorporant des cellules B de lymphome, de la matrice extracellulaire et/ou des cellules stromales d’amygdale. Nous avons montré que les cellules de lymphome B étaient capables de former des sphéroïdes cohésifs résultant de la surexpression des composants de la matrice extra-cellulaire. De plus, dans ce modèle, les cellules stromales s’auto-organisent pour initier la prolifération des cellules tumorales. La culture 3D induit une résistance à l'agent chimiothérapeutique classique doxorubicine, mais pas à l'inhibiteur de BCL2 ABT-199, identifiant cette approche comme un modèle in vitro pertinent pour comprendre l’activité des agents thérapeutiques . L'analyse RNAseq a mis en évidence des modulations des voies de signalisation similaires à celles observées dans les cellules primaires de lymphome folliculaire. Enfin, notre modèle a permis la survie à long terme in vitro de cellules B primaires de lymphome folliculaire. Nous proposons ainsi un nouveau modèle 3D imitant la niche tumorale du lymphome et permettant d'étudier la relation dynamique entre les cellules tumorales et leur microenvironnement pour les tests de nouveaux médicaments anticancéreux. En parallèle, nous avons pour la première fois, initié la caractérisation d’une niche tumorale jusqu’alors jamais explorée dans le lymphome folliculaire, située dans le tissu adipeux péri-ganglionnaire. Dans cette niche, les cellules tumorales évoluent au contact de cellules stromales adoptant un phénotype CAF associé aux tumeurs solides, et de macrophages associés aux tumeurs de phénotype M2

Epstein–Barr Virus-Associated T- and NK-Cell Lymphoproliferative Diseases: A Review of Clinical and Pathological Features

Epstein–Barr virus (EBV) is a ubiquitous virus detected in up to 95% of the general population. Most people are asymptomatic, while some may develop a wide range of EBV-associated lymphoproliferative disorders (LPD). Among them, EBV-positive T/NK LPD are uncommon diseases defined by the proliferation of T- or NK-cells infected by EBV. The 2017 World Health Organization (WHO) classification recognizes the following entities characterized by different outcomes: chronic active EBV infection of T- or NK-cell types (cutaneous and systemic forms), systemic EBV-positive T-cell lymphoma of childhood, EBV-positive aggressive NK-cell leukemia, extra nodal NK/T-cell lymphoma nasal type, and the new provisional entity known as primary EBV-positive nodal T/NK-cell lymphoma. In addition, EBV associated-hemophagocytic lymphohistiocytosis is part of EBV-positive T/NK LPD, but has not been included in the WHO classification due to its reactive nature. Despite novel insights from high-throughput molecular studies, EBV-positive NK/T-cell LPD diagnoses remain challenging, especially because of their rarity and overlap. Until now, an accurate EBV-positive NK/T LPD diagnosis has been based on its clinical presentation and course correlated with its histological features. This review aims to summarize clinical, pathological and molecular features of EBV-positive T/NK LPD subtypes and to provide an overview of new understandings regarding these rare disorders

Renouncing care in French Guiana: the national health barometer survey

Abstract Background In French Guiana, health inequalities are patent for a broad range of pathologies for all age groups. The objective of the present study was to quantify the proportion of the population that had renounced care in the past year, to study predictive factors, and to compare results with other French territories. Methods A two-stage random sample of 2015 individuals aged 15 to 75 years was surveyed by telephone. A descriptive analysis of variables relative to renouncing care, use of health care, screening, and vaccination was initially performed. Multivariate analysis was then used to determine variables associated with renouncing care for financial reasons and renouncing for reasons linked to time were directly estimated using a Poisson model on weighted data. Variables with a significance level < 0.2 in the bivariate analysis were included in the full multivariate model. Results In French Guiana, during the past 12 months, 30.9% of surveyed persons renounced care whatever the type for financial reasons. Results of the multivariate analysis showed that gender, perceived financial situation, perceived health and complementary insurance status were independent predictive factors of care renouncement for financial reasons. Overall, 24% of the surveyed population declared having renounced to care for time-related motives. The independent predictors for time-related renouncing were different than those for renouncing care for financial reasons: a higher education level and a poor perceived health were independently associated with time-related renouncement; retired persons and students were found to renounce care less frequently than persons with a job. Conclusions Renouncing for financial reasons, a major target of the 2016 health law, represented a public health problem in French Guiana. Renouncing for lack of time was an important motive for renouncing, which is aggravated by the insufficient number of health professionals, but may benefit from organizational solutions. There are avenues for improvement of health for the most vulnerable: promote health, act on risk factors, and facilitate the readability and accessibility of the health system. Recent reforms to stabilize health insurance may however have some adverse consequences for migrants

Servitudes et libertés dans les Amériques avant l’abolition de l’esclavage

Ce numéro est le fruit de deux journées d'études organisées respectivement à l'université de Poitiers et à l'université Paul Valéry Montpellier 3 en 2015 et en 2016. La première journée portait sur le travail contraint dans les Amériques avant l'abolition des esclavages, en s'intéressant en particulier aux codifications juridiques, aux transferts et à l'harmonisation des pratiques. La seconde traitait des modalités de libération des travailleurs non-libres dans les Amériques avant l'abolition de l'esclavage

Histological Subtypes Drive Distinct Prognostic Immune Signatures in Classical Hodgkin Lymphoma

International audienceSimple Summary Classical Hodgkin lymphoma (cHL) is a highly curable disease, with about 80% of patients cured using standard first-line chemotherapy. However, outcomes for relapsed/refractory patients remain unfavorable and there is a critical lack of predictive biomarkers for early identification of these patients who may benefit from new therapeutic strategies. Here we evaluated the dynamic expression of 586 immune-related genes in a cohort of 42 cHL patients using NanoString technology. We identified a 19-gene immune signature predictive of relapse at the time of diagnosis, which was found to be strongly dependent on histological subtype. Moreover, comparative analyses between paired diagnostic/relapsed biopsies of nodular sclerosis cHL showed 118 differentially expressed genes, highlighting an immune contexture shift at relapse not found in mixed-cellularity cases. Overall, these results strongly suggest that the predictive value of immune signature in cHL is influenced by histological subtype, a criterion that should be considered when assessing new immunotherapy strategies. Despite the success of standard front-line chemotherapy, 20% of classical Hodgkin lymphoma (cHL) patients still relapse or have refractory disease (r/r), and a subset of them die due to disease progression. There is a critical lack of predictive factors for early identification of those r/r patients who may benefit from new therapeutic strategies. This study aimed to evaluate the dynamic expression of 586 immune-related genes in a cohort of 42 cHL patients including 30 r/r cHL after first-line chemotherapy. Gene expression profiling (GEP) using NanoString technology identified a 19-gene immune signature at diagnosis predictive of cHL relapse, but dependent on histological subtypes. Genes related to tumor survival were found upregulated while genes related to B-lineage were downregulated at diagnosis in r/r nodular sclerosis cHL. In contrast to the mixed-cellularity subtype, comparative GEP analyses between paired diagnosis/relapse biopsies of nodular sclerosis cHL showed 118 differentially expressed genes, supporting an immune contexture switch at relapse with upregulation of immunosuppressive cytokines, such as LGALS1 and TGFB1, and downregulation of the T-cell co-stimulatory receptor ICOS. These results indicate that the predictive value of immune signature in cHL is strongly influenced by histological subtype which should be considered when assessing new immunotherapy target strategies

Follicular lymphoma regulatory T-cell origin and function

International audienceIntroduction: Follicular Lymphoma (FL) results from the malignant transformation of germinal center (GC) B cells. FL B cells display recurrent and diverse genetic alterations, some of them favoring their direct interaction with their cell microenvironment, including follicular helper T cells (Tfh). Although FL-Tfh key role is well-documented, the impact of their regulatory counterpart, the follicular regulatory T cell (Tfr) compartment, is still sparse.Methods: The aim of this study was to characterize FL-Tfr phenotype by cytometry, gene expression profile, FL-Tfr origin by transcriptomic analysis, and functionality by in vitro assays.Results: CD4+CXCR5+CD25hiICOS+ FL-Tfr displayed a regulatory program that is close to classical regulatory T cell (Treg) program, at the transcriptomic and methylome levels. Accordingly, Tfr imprinting stigmata were found on FL-Tfh and FL-B cells, compared to their physiological counterparts. In addition, FL-Tfr co-culture with autologous FL-Tfh or cytotoxic FL-CD8+ T cells inhibited their proliferation in vitro. Finally, although FL-Tfr shared many characteristics with Treg, TCR sequencing analyses demonstrated that part of them derived from precursors shared with FL-Tfh.Discussion: Altogether, these findings uncover the role and origin of a Tfr subset in FL niche and may be useful for lymphomagenesis knowledge and therapeutic management

Clinical and histological features of histiocytoid Sweet syndrome associated with VEXAS syndrome

International audienceBACKGROUND: &quot;Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic&quot; (VEXAS) syndrome is caused by acquired somatic mutations in the ubiquitin-activating enzyme 1 (UBA1) gene. Sweet-syndrome-like skin disorders (and especially histiocytoid Sweet syndrome (HSS)) may be associated with VEXAS syndrome. OBJECTIVE: To characterize the clinical and histopathological features of HSS in patients with VEXAS syndrome. METHODS: The skin biopsies with a histological diagnosis of HSS had been collected at Rennes University Medical Center (Rennes, France) between October 2011 and January 2022. Sanger sequencing and digital PCR were used to screen skin, blood, and bone marrow samples for UBA1 variants, and thus classify patients as having VEXAS syndrome or not. We evaluated the clinical, histological, and molecular (UBA1) characteristics of patients with or without VEXAS syndrome. RESULTS: We compared 15 skin biopsies from seven patients found to have VEXAS syndrome and 19 skin biopsies from 15 patients without VEXAS syndrome. Persistent inflammatory syndrome, macrocytosis, anemia, and hematological malignancies were more prevalent in patients with VEXAS syndrome (86%, 86%, 100%, and 86%, respectively) than in patients without (36%, 40%, 53%, and 53%, respectively). These features sometimes appeared after the first skin manifestations, and a UBA1 mutation was found in the skin of five patients with VEXAS syndrome. Dermal infiltration by myeloperoxidase-positive, CD163-positive, reniform histiocytoid cells and a periadnexal distribution were more frequently observed in VEXAS syndrome biopsies (100% and 20% respectively, vs. 58% and 0% in non-VEXAS syndrome biopsies, respectively). CONCLUSION: Our findings might help the pathologist to consider a diagnosis of VEXAS syndrome and to initiate early genetic testing

Committed Human CD23-Negative Light-Zone Germinal Center B Cells Delineate Transcriptional Program Supporting Plasma Cell Differentiation

International audienceB cell affinity maturation occurs in the germinal center (GC). Light-zone (LZ) GC B cells (B-GC-cells) interact with follicular dendritic cells (FDCs) and compete for the limited, sequential help from T follicular helper cells needed to escape from apoptosis and complete their differentiation. The highest-affinity LZ B-GC-cells enter the cell cycle and differentiate into PCs, following a dramatic epigenetic reorganization that induces transcriptome changes in general and the expression of the PRDM1 gene in particular. Human PC precursors are characterized by the loss of IL-4/STAT6 signaling and the absence of CD23 expression. Here, we studied the fate of human LZ B-GC-cells as a function of their CD23 expression. We first showed that CD23 expression was restricted to the GC LZ, where it was primarily expressed by FDCs; less than 10% of tonsil LZ B-GC-cells were positive. Sorted LZ B-GC-cells left in culture and stimulated upregulated CD23 expression but were unable to differentiate into PCs - in contrast to cells that did not upregulate CD23 expression. An in-depth analysis (including single-cell gene expression) showed that stimulated CD23-negative LZ B-GC-cells differentiated into plasmablasts and time course of gene expression changes delineates the transcriptional program that sustains PC differentiation. In particular, we identified a B cell proliferation signature supported by a transient MYC gene expression. Overall, the CD23 marker might be of value in answering questions about the differentiation of normal B-GC-cells and allowed us to propose an instructive LZ B-GC-cells maturation and fate model