Germinal center reaction

Follicular helper T (TFH) cells are essential for inducing germinal center (GC) reactions to mediate humoral adaptive immunity in tumors, but the mechanisms underlying TFH cell differentiation remain unclear. Here, we found that the metabolism sensor sirtuin 3 (SIRT3) is critical for TFH cell differentiation and GC formation during tumor and viral infection. SIRT3 deficiency in CD4+ T cells intrinsically enhanced TFH cell differentiation and GC reactions during tumor and virus infection. Mechanistically, damaged oxidative phosphorylation (OXPHOS) compensatively triggered the NAD+-glycolysis pathway to provide a cellular energy supply, which was necessary for SIRT3 deficiency-induced TFH cell differentiation...

Carrier-free naked mRNA vaccines may reduce the reactogenicity associated with delivery carriers; however, their effectiveness against infectious diseases has been suboptimal. To boost efficacy, we targeted the skin layer rich in antigen-presenting cells (APCs) and utilized a jet injector. The jet injection efficiently introduced naked mRNA into skin cells, including APCs in mice. Further analyses indicated that APCs, after taking up antigen mRNA in the skin, migrated to the lymph nodes (LNs) for antigen presentation...

We characterized 5 B-cell tumors carrying t(14;19)(q32;q13) that creates the IGH::BCL3 fusion gene. The patients' ages ranged between 55 and 88 years. Two patients presented with progression or recurrence of B-cell chronic lymphocytic leukemia (B-CLL)/small lymphocytic lymphoma (SLL), two with diffuse large B-cell lymphoma (DLBCL) of non-germinal center B-like phenotype, and the remaining one with composite angioimmunoblastic T-cell lymphoma and Epstein-Barr virus-positive DLBCL. The presence of t(14;19)(q32;q13) was confirmed by fluorescence in situ hybridization (FISH), showing colocalization of 3' IGH and 3' BCL3 probes on der(14)t(14;19) and 5' BCL3 and 5' IGH probes on der(19)t(14;19)...

Follicular lymphoma (FL), the most common indolent B-cell lymphoma, develops over decades before manifesting as overt disease. BCL2 overexpression by t(14;18) confers a survival advantage to B cells during the germinal center reaction, and abnormalities in epigenetic modifier genes lead to desynchronization of gene expression changes in germinal center B cells. Studies in mouse models have shown that BCL2 overexpression and epigenetic deregulation in B cells cooperatively promote lymphomagenesis. The immune microenvironment also plays an essential role in the biology of FL, and many molecular prognostic indicators based on the immune microenvironment have been proposed...

This paper provides data regarding the ratios of the functional structures of lymph nodes after inflammation in the abdominal organs. Lymph systems, including lymph nodes, function as filters of tissues and tissue fluids and are places of origin and lymphocyte production for normal physiological functions. They display specific morphological and functional responses in reaction to endogenous and exogenous substances. The morphological pattern of the mesenteric lymph node in experimental rat groups reflects a decrease in its immune function due to the processes of inflammation in the abdominal cavity...

Memory B cells (MBCs) play a critical role in protection against homologous and variant pathogen challenge by either differentiating to plasma cells (PCs) or to germinal center (GC) B cells. The human MBC compartment contains both switched IgG+ and unswitched IgM+ MBCs; however, whether these MBC subpopulations are equivalent in their response to B cell receptor cross-linking and their resulting fates is incompletely understood. Here, we show that IgG+ and IgM+ MBCs can be distinguished based on their response to κ-specific monoclonal antibodies of differing affinities...

The germinal center response or reaction (GCR) is a hallmark event of adaptive humoral immunity. Unfolding in the B cell follicles of the secondary lymph organs, a GC culminates in the production of high-affinity antibody-secreting plasma cells along with memory B cells. By interacting with follicular dendritic cells (FDC) and T follicular helper (Tfh) cells, GC B cells exhibit complex spatiotemporal dynamics. Driving the B cell dynamics are the intracellular signal transduction and gene regulatory network that responds to cell surface signaling molecules, cytokines, and chemokines...

Marginal zone (MZ) B cells bridge innate and adaptive immunity by sensing bloodborne antigens and producing rapid antibody and cytokine responses. CD55 is a membrane-bound complement regulator that interferes with complement activation, an important component of innate immunity. CD55 also regulates adaptive immunity-CD55 downregulation is critical for germinal center reactions. MZ B cells also express low CD55, but its role in MZ B cell function is unknown. Using germline knockout mice, we found that similar numbers of MZ B cells are initially established in 3-week-old CD55-deficient mice compared to wild-type (WT) mice...

Development of Plasmodium-specific humoral immunity is critically dependent on CD4 Th cell responses and germinal center (GC) reactions during blood-stage Plasmodium infection. IL-21, a cytokine primarily produced by CD4 T cells, is an essential regulator of affinity maturation, isotype class-switching, B cell differentiation, and maintenance of GC reactions in response to many infection and immunization models. In models of experimental malaria, mice deficient in IL-21 or its receptor IL-21R fail to develop memory B cell populations and are not protected against secondary infection...

Nipah virus (NiV) has been recently ranked by the World Health Organization as being among the top eight emerging pathogens likely to cause major epidemics, whereas no therapeutics or vaccines have yet been approved. We report a method to deliver immunogenic epitopes from NiV through the targeting of the CD40 receptor of antigen-presenting cells by fusing a selected humanized anti-CD40 monoclonal antibody to the Nipah glycoprotein with conserved NiV fusion and nucleocapsid peptides. In the African green monkey model, CD40...

Follicular helper T cells (Tfh) play a crucial role in generating high-affinity antibodies (Abs) and establishing immunological memory. Cytokines, among other functional molecules produced by Tfh, are central to germinal center (GC) reactions. This review focuses on the role of cytokines, including IL-21 and IL-4, in regulating B cell responses within the GC, such as differentiation, affinity maturation, and plasma cell development. Additionally, this review explores the impact of other cytokines like CXCL13, IL-10, IL-9, and IL-2 on GC responses and their potential involvement in autoimmune diseases, allergies, and cancer...

Viral mimicry of host cell structures has been postulated to curtail the B cell receptor (BCR) repertoire against persisting viruses through tolerance mechanisms. This concept awaits, however, experimental testing in a setting of natural virus-host relationship. We engineered mouse models expressing a monoclonal BCR specific for the envelope glycoprotein of lymphocytic choriomeningitis virus (LCMV), a naturally persisting mouse pathogen. When the heavy chain of the LCMV-neutralizing antibody KL25 was paired with its unmutated ancestor light chain, most B cells underwent receptor editing, a behavior reminiscent of autoreactive clones...

Autoimmune diseases strain healthcare systems worldwide as their incidence rises, and current treatments put patients at risk for infections. An increased understanding of autoimmune diseases is required to develop targeted therapies that do not impair normal immune function. Many autoimmune diseases present with autoantibodies, which drive local or systemic inflammation. This indicates the presence of autoreactive B cells that have escaped tolerance. An important step in the development of autoreactive B cells is the germinal center (GC) reaction, where they undergo affinity maturation toward cognate self-antigen...

The development of novel phytotoxic compounds has been an important aim of weed control research. In this study, we synthesized fluorinated chalcone derivatives featuring both electron-donating and electron-withdrawing groups. These compounds were evaluated both as inhibitors of the photosystem II (PSII) electron chain as well as inhibitors of the germination and seedling growth of Amaranthus plants. Chlorophyll a (Chl a) fluorescence assay was employed to evaluate their effects on PSII, while germination experiments were conducted to assess their impact on germination and seedling development...

Sequence studies of the entire exome and transcriptome of lymphoma tissues have identified MYD88 and PIM1 as involved in the development and oncogenic signaling. We aimed to determine the frequency of MYD88 and PIM1 mutations, as well as their expressions in conjunction with the clinicopathological parameters identified in mature large B-cell non-Hodgkin lymphomas. The ten-year retrospective study included 50 cases of mature large B-cell lymphoma, diagnosed at the Pathology Department of the Emergency County Hospital of Constanţa and Săcele County Hospital of Brasov...

CD11c+ atypical B cells (ABCs) are an alternative memory B cell lineage associated with immunization, infection, and autoimmunity. However, the factors that drive the transcriptional program of ABCs have not been identified, and the function of this population remains incompletely understood. Here we identified candidate transcription factors associated with the ABC population based on a human tonsillar B cell single cell dataset. We identified CD11c+ B cells in mice with a similar transcriptomic signature to human ABCs, and using an optimized CRISPR-Cas9 knockdown screen, we observed that loss of zinc finger E-box binding homeobox 2 (Zeb2) impaired ABC formation...

BACKGROUND: Ataxia Telangiectasia (AT) is characterized by cerebellar ataxia, telangiectasia, immunodeficiency, and increased cancer susceptibility, caused by mutations in the ataxia telangiectasia mutated (ATM) gene. The immunodeficiency comprises predominantly immunoglobulin (Ig)-deficiency, mainly IgA and IgG2, with a variable severity. So far, the exact mechanisms underlying the Ig-deficiency, especially the variable severity, remain unelucidated. OBJECTIVE: To characterize the clinical impact of Ig-deficiencies in AT and to elucidate the mechanisms of Ig-deficiencies in AT...

BACKGROUND: Factor IX inhibitor formation is the most serious complication of replacement therapy for the bleeding disorder hemophilia B, exacerbated by severe allergic reactions occurring in up to 60% of patients with inhibitors. Low success rates of immune tolerance induction therapy in hemophilia B necessitate the search for novel immune tolerance therapies. Skin-associated lymphoid tissues have been successfully targeted in allergen-specific immunotherapy. OBJECTIVES: We aimed to develop a prophylactic immune tolerance protocol based on intradermal administration of FIX that would prevent inhibitor formation and/or anaphylaxis in response to replacement therapy...

UNLABELLED: Unlike in infection and cancer, T cell exhaustion in autoimmune disease has not been clearly defined. Here we set out to understand inhibitory protein (PD-1, Tim3, CTLA4, Lag3) expression in CXCR5- and CXCR5+ CD8 and CD4 T cells in systemic lupus erythematosus. CXCR5+ CD8 and CD4 T cells express PD-1 and engage B cells in germinal center reactions, leading to autoantibody formation in autoimmunity. We hypothesized that CXCR5+ CD8 T cells develop an exhausted phenotype as SLE autoimmunity expands from initial to chronic, self-perpetuating disease due to chronic self-antigen exposure...

Reactive lymphoid hyperplasia (RLH) of the liver is extremely rare. Despite advancements in diagnostic imaging technology, it is still difficult to distinguish from hepatocellular carcinoma (HCC). Herein, we present a case of hepatic RLH mimicking HCC that was postoperatively diagnosed using several imaging modalities. A 78-year-old female was referred to our hospital with a positive hepatitis C virus antibody (HCV Ab) test. Ultrasonography revealed a 13 mm isoechoic lesion in segment 8 of the liver. Contrast-enhanced computed tomography (CE-CT) demonstrated arterial hyperintensity and washout during the later phase...