Expression of RAG and secondary gene rearrangement of BCR in mature peripheral B lymphocytes in Takayasu arteritis.

To evaluate the expression of recombinant activating gene (RAG) and B cell receptor (BCR) gene rearrangements in mature peripheral B lymphocytes in Takayasu arteritis (TA) to explore the possible mechanism of humoral immune response in TA. Ten patients with TA and 10 age- and sex-matched healthy volunteers (control group) from Beijing Shijitan Hospital, Capital Medical University and Peking Union Medical College Hospital, between 2022 and 2023, were included in this study. The mRNA of the RAG was measured using real-time quantitative PCR (RT-PCR). Western blotting was used to detect RAG protein expression levels. NGS technology was used to detect BCR gene rearrangement. The mRNA expression level of RAG1 and RAG2 in peripheral mature B lymphocytes in patients with TA was significantly higher than in the control group (RAG1 5.56 ± 1.71 vs. 1.94 ± 0.86, p < 0.05; RAG2 5.26 ± 1.59 vs. 1.65 ± 0.64, p < 0.05), respectively. The protein expression level of the RAG1 and the RAG2 in peripheral mature B lymphocytes in patients with TA was significantly higher than in the healthy control group (RAG1 4.33 ± 1.58 vs. 1.52 ± 0.59, p < 0.001; RAG2 4.67 ± 1.88 vs. 1.59 ± 0.56, p < 0.001). The number of peripheral B lymphocyte BCR clonotypes in the group of patients with TA was significantly higher than in the normal control group (1574 ± 317.7 vs. 801.3 ± 202.1, p < 0.05). The abundance of IGHV clones in patients with TA was higher than in the normal control group (31.185% vs. 13.449%), which was positively correlated with the expression levels of RAG1 and RAG2 (correlation coefficient r = 1.00, p < 0.001), respectively. High expression of the RAG gene coexists with secondary BCR gene rearrangement in mature peripheral B lymphocytes in patients with TA, providing important clues regarding the potential humoral response in TA; however, further studies with larger samples are needed.

Rosa roxburghii Tratt (Cili) has a more effective capacity in alleviating DSS-induced colitis compared to Vitamin C through B cell receptor pathway.

Rosa roxburghii Tratt (RRT), a traditional Chinese plant known as the 'King of Vitamin C (VitC; ascorbic acid, AsA)', contains a wealth of nutrients and functional components, including polysaccharides, organic acids, flavonoids, triterpenes, and high superoxide dismutase (SOD) activity. The various functional components of RRT suggest that it may theoretically have a stronger potential for alleviating colitis compared to VitC. This study aims to verify whether RRT has a stronger ability to alleviate colitis than equimolar doses of VitC and to explore the mechanisms underlying this improvement. Results showed that RRT significantly mitigated body weight loss, intestinal damage, elevated inflammation levels, and compromised barriers in mice induced by Dextran sulfate sodium (DSS). Additionally, RRT enhanced the diversity and composition of intestinal microbiota in these DSS-induced mice. Colon RNA sequencing analysis revealed that compared to VitC, RRT further downregulated multiple immune-related signaling pathways, particularly the B cell receptor (BCR) pathway, which is centered around genes like Btk and its downstream PI3K-AKT, NF-κB, and MAPK signaling pathways. Correlation analysis between microbiota and genes demonstrated a significant relationship between the taxa improved by RRT and the key genes in the BCR and its downstream signaling pathways. Overall, RRT exhibited superior capabilities in alleviating DSS-induced colitis compared to VitC by decreasing intestinal inflammation and modulating BCR and its downstream signaling pathways, potentially regulated by the improved intestinal microbiota.

Genetic regulation of B cell receptor signaling pathway: Insights from expression quantitative trait locus analysis using a mixed model.

The B cell receptor (BCR) signaling pathway regulates non-immune cellular response through various pathways like MAPK, NF-kB, and PI3K-Akt. This study aimed to identify expression quantitative trait loci (eQTL) and their regulatory functions on BCR signaling pathway genes. A mixed model was employed to analyze eQTL using RNA expression levels in lymphoblastoid from 376 Europeans in the GEUVADIS dataset. In total, 266 SNPs, including 115 cis-acting SNPs, were found for association with transcription of 13 genes (P < 5 × 10-8), revealing 19 independent signals for five genes through linkage disequilibrium analysis. Functional analysis, aligning them with DNase sensitive sites, transcription factor binding sites, histone modification, promoters/enhancers, CpG islands, and ChIA-PET, identified regulatory variants targeting SYK, VAV2, and PLCG2. Notably, rs2562397 was validated as a SYK promoter variant, and rs694505, rs636667, and rs4889409 were confirmed as enhancer variants for VAV2 and PLCG2. Their allelic differences in gene expression were also confirmed using ENCODE ChIP-seq and Sei neural network prediction. Persistent differential expression of these genes by alleles might impact the adaptive immune system, vascular development, and/or relevant diseases that have been previously associated with other variants of the genes. Comprehensive genetic architecture studies of the BCR signaling pathway, along with experiments demonstrating related mechanisms, will greatly contribute to understanding the underlying mechanisms of relevant disease development and implementing precision medicine.

A genome assembly and transcriptome atlas of the inbred Babraham pig to illuminate porcine immunogenetic variation.

The inbred Babraham pig serves as a valuable biomedical model for research due to its high level of homozygosity, including in the major histocompatibility complex (MHC) loci and likely other important immune-related gene complexes, which are generally highly diverse in outbred populations. As the ability to control for this diversity using inbred organisms is of great utility, we sought to improve this resource by generating a long-read whole genome assembly and transcriptome atlas of a Babraham pig. The genome was de novo assembled using PacBio long reads and error-corrected using Illumina short reads. Assembled contigs were then mapped to the porcine reference assembly, Sscrofa11.1, to generate chromosome-level scaffolds. The resulting TPI_Babraham_pig_v1 assembly is nearly as contiguous as Sscrofa11.1 with a contig N50 of 34.95 Mb and contig L50 of 23. The remaining sequence gaps are generally the result of poor assembly across large and highly repetitive regions such as the centromeres and tandemly duplicated gene families, including immune-related gene complexes, that often vary in gene content between haplotypes. We also further confirm homozygosity across the Babraham MHC and characterize the allele content and tissue expression of several other immune-related gene complexes, including the antibody and T cell receptor loci, the natural killer complex, and the leukocyte receptor complex. The Babraham pig genome assembly provides an alternate highly contiguous porcine genome assembly as a resource for the livestock genomics community. The assembly will also aid biomedical and veterinary research that utilizes this animal model such as when controlling for genetic variation is critical.

The immunoglobulin M-degrading enzyme of Streptococcus suis (IdeSsuis) leads to long-lasting inhibition of the activation of porcine IgM-secreting B cells.

Streptococcus suis (S. suis) is one of the most important porcine pathogens, causing severe pathologies such as meningitis or polyarthritis. It is also a very successful colonizer of mucosal surfaces. The IgM-degrading enzyme of S. suis (IdeSsuis) specifically cleaves porcine IgM, which results in complement evasion. On the basis of our previous finding that IdeSsuis also cleaves the IgM B cell receptor in vitro, we verified IgM B cell receptor cleavage ex vivo in whole regional lymph nodes and investigated the working hypothesis that this IgM B cell receptor cleavage results in a long-lasting impaired B cell function. The number of IgM-secreting cells was determined via ELISpot analysis after porcine peripheral blood mononuclear cells had initially been treated with different recombinant S. suis proteins and subsequently stimulated with interleukin-2 and the toll-like receptor 7/8 ligand R848. Compared with treatment with medium or recombinant muramidase-released protein, treatment with rIdeSsuis but also with a cleavage-deficient variant led to a reduction in the number of IgM-secreting cells as well as the level of secreted IgM. Flow cytometry analysis confirmed that the IgM B cell receptor was cleaved only by rIdeSsuis, and the receptor recovered to pretreatment levels on day 2 after treatment. Flow cytometry analysis of B and T cells incubated with fluorescein-labelled recombinant proteins revealed that different rIdeSsuis variants bind specifically to B cells, most prominently the cleavage-deficient variant. Our results indicate that in vitro interference of rIdeSsuis with the IgM B cell receptor results in long-lasting impaired IgM secretion by B cells after toll-like receptor activation. Further studies are warranted to prove that the modulation of B cell function by IdeSsuis could play a role in vivo.

BCR signaling in germinal center B cell selection.

When mature B cells are activated by antigens, the selection of these activated B cells takes place particularly during T cell-dependent immune responses in which an improved antibody repertoire is generated through somatic hypermutation in germinal centers (GCs). In this process the importance of antigen presentation by GC B cells, and subsequent T follicular helper (Tfh) cell help in positive selection of GC B cells, has been well appreciated. By contrast, the role of B cell receptor (BCR) signaling per se remains unclear. Strong experimental support for the involvement of BCR signaling in GC B cell selection has now been provided. Interestingly, these studies suggest that several checkpoints operating through the BCR ensure affinity maturation.

Deep mutational scanning reveals transmembrane features governing surface expression of the B cell antigen receptor.

B cells surveil the body for foreign matter using their surface-expressed B cell antigen receptor (BCR), a tetrameric complex comprising a membrane-tethered antibody (mIg) that binds antigens and a signaling dimer (CD79AB) that conveys this interaction to the B cell. Recent cryogenic electron microscopy (cryo-EM) structures of IgM and IgG isotype BCRs provide the first complete views of their architecture, revealing that the largest interaction surfaces between the mIg and CD79AB are in their transmembrane domains (TMDs). These structures support decades of biochemical work interrogating the requirements for assembly of a functional BCR and provide the basis for explaining the effects of mutations. Here we report a focused saturating mutagenesis to comprehensively characterize the nature of the interactions in the mIg TMD that are required for BCR surface expression. We examined the effects of 600 single-amino-acid changes simultaneously in a pooled competition assay and quantified their effects by next-generation sequencing. Our deep mutational scanning results reflect a feature-rich TMD sequence, with some positions completely intolerant to mutation and others requiring specific biochemical properties such as charge, polarity or hydrophobicity, emphasizing the high value of saturating mutagenesis over, for example, alanine scanning. The data agree closely with published mutagenesis and the cryo-EM structures, while also highlighting several positions and surfaces that have not previously been characterized or have effects that are difficult to rationalize purely based on structure. This unbiased and complete mutagenesis dataset serves as a reference and framework for informed hypothesis testing, design of therapeutics to regulate BCR surface expression and to annotate patient mutations.

Virus-driven dysregulation of the BCR pathway: a potential mechanism for the high prevalence of HIV related B-cell lymphoma.

In people living with HIV (PLWH), the susceptibility to malignancies is notably augmented, with lymphoma emerging as a predominant malignancy. Even in the antiretroviral therapy (ART) era, aggressive B-cell lymphoma stands out as a paramount concern. Yet, the pathogenesis of HIV related lymphoma (HRL) largely remains an enigma. Recent insights underscore the pivotal role of the dysregulated B cell receptor (BCR) signaling cascade, evidencing its oncogenic potential across a spectrum of lymphomas. Intricate interplays between HIV and BCR structural-functional integrity have been identified in PLWH. In this review, we elucidated the mechanism by which the BCR signaling pathway is involved in HRL, mainly including the following aspects: HIV can reshape BCR structure by modulating of activation-induced cytidine deaminase (AID) and recombination-activating gene (RAG) dynamics; HIV can act as a chronic antigen to activate the BCR signaling pathway, such as upregulating PI3K and MAPK signaling pathway and reducing the expression of CD300a; HIV co-infection with other oncogenic viruses may also influence tumor formation mediated by the BCR signaling pathway. This review aims to elucidate the intricate regulation of the BCR signaling pathway by HIV in B cell lymphoma, providing a novel perspective on the pathogenesis of lymphoma in HIV-affected environments.

Analysis of B-cell receptor repertoire to evaluate immunogenicity of monovalent Omicron XBB.1.5 mRNA vaccines.

Monovalent Omicron XBB.1.5 mRNA vaccines were newly developed and approved by the FDA in Autumn 2023 for preventing COVID-19. However, clinical efficacy for these vaccines is currently lacking. We previously established the quantification of antigen-specific antibody sequence (QASAS) method to assess the response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination at the mRNA level using B-cell receptor (BCR) repertoire assay and the coronavirus antibody database (CoV-AbDab). Here, we used this method to evaluate the immunogenicity of monovalent XBB.1.5 vaccines. We analyzed repeated blood samples of healthy volunteers before and after monovalent XBB.1.5 vaccination (BNT162b2 XBB.1.5 or mRNA-1273.815) for the BCR repertoire to assess BCR/antibody sequences that matched SARS-CoV-2-specific sequences in the database. The number of matched unique sequences and their total reads quickly increased 1 week after vaccination. Matched sequences included those bound to the Omicron strain and Omicron XBB sublineage. The antibody sequences that can bind to the Omicron strain and XBB sublineage revealed that the monovalent XBB.1.5 vaccines showed a stronger response than previous vaccines or SARS-CoV-2 infection before the emergence of XBB sublineage. The QASAS method was able to demonstrate the immunogenic effect of monovalent XBB.1.5 vaccines for the 2023-2024 COVID-19 vaccination campaign.

E41K mutation activates Bruton's tyrosine kinase by stabilizing an inositol hexakisphosphate-dependent invisible dimer.

Bruton's tyrosine kinase (BTK) regulates diverse cellular signaling of the innate and adaptive immune system in response to microbial pathogens. Downregulation or constitutive activation of BTK is reported in patients with autoimmune diseases or various B-cell leukemias. BTK is a multidomain protein tyrosine kinase that adopts an Src-like autoinhibited conformation maintained by the interaction between the kinase and PH-TH domains. The PH-TH domain plays a central role in regulating BTK function. BTK is activated by binding to PIP3 at the plasma membrane upon stimulation by the B-cell receptor (BCR). The PIP3 binding allows dimerization of the PH-TH domain and subsequent transphosphorylation of the activation loop. Alternatively, a recent study shows that the multivalent T-cell-independent (TI) antigen induces BCR response by activating BTK independent of PIP3 binding. It was proposed that a transiently stable IP6-dependent PH-TH dimer may activate BTK during BCR activation by the TI antigens. However, no IP6-dependent PH-TH dimer has been identified yet. Here, we investigated a constitutively active PH-TH mutant (E41K) to determine if the elusive IP6-dependent PH-TH dimer exists. We showed that the constitutively active E41K mutation activates BTK by stabilizing the IP6-dependent PH-TH dimer. We observed that a downregulating mutation in the PH-TH domain (R28H) linked to X-linked agammaglobulinemia impairs BTK activation at the membrane and in the cytosol by preventing PH-TH dimerization. We conclude that the IP6 dynamically remodels the BTK active fraction between the membrane and the cytoplasm. Stimulating with IP6 increases the cytosolic fraction of the activated BTK.

Case report: Persistent hypogammaglobulinemia and mixed chimerism after HLA class-II disparate-hematopoietic stem cell transplant.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for various hematological, immunological and metabolic diseases, replacing the patient's hematopoietic system with donor-derived healthy hematopoietic stem cells. HSCT can be complicated by early and late events related to impaired immunological recovery such as prolonged hypogammaglobulinemia post-HSCT. We present a 16-year-old female patient with sickle-cell disease who underwent HSCT with stem cells from a human leukocyte antigen (HLA) class-II mismatched family donor. While cellular recovery was good post-HSCT, the patient developed mixed chimerism and suffered from cervical lymphadenopathy, recurrent airway infections and cutaneous SLE. She presented with hypogammaglobulinemia and was started on immunoglobulin substitution therapy and antibiotic prophylaxis. B-cell phenotyping showed that she had increased transitional and naïve mature B cells, reduced memory B cells, and diminished marginal zone/natural effector cells. In-depth immunophenotyping and B-cell receptor repertoire sequencing ruled out an intrinsic B-cell defect by expression of activation-induced cytidine deaminase (AID), presence of somatic hypermutations and differentiation into IgG- and IgA-producing plasma cells in vitro. Immunohistochemistry and flow cytometry of lymph node tissue showed a clear block in terminal B-cell differentiation. Chimerism analysis of sorted lymph node populations showed that exclusively patient-derived B cells populated germinal centers, while only a minor fraction of follicular helper T cells was patient-derived. Given this discrepancy, we deduced that the HLA class-II disparity between patient and donor likely hinders terminal B-cell differentiation in the lymph node. This case highlights that studying disturbed cognate T-B interactions in the secondary lymphoid organs can provide unique insights when deciphering prolonged hypogammaglobulinemia post-HSCT.

Computational mining of B cell receptor repertoires reveals antigen-specific and convergent responses to Ebola vaccination.

Outbreaks of Ebolaviruses, such as Sudanvirus (SUDV) in Uganda in 2022, demonstrate that species other than the Zaire ebolavirus (EBOV), which is currently the sole virus represented in current licensed vaccines, remain a major threat to global health. There is a pressing need to develop effective pan-species vaccines and novel monoclonal antibody-based therapeutics for Ebolavirus disease. In response to recent outbreaks, the two dose, heterologous Ad26.ZEBOV/MVA-BN-Filo vaccine regimen was developed and was tested in a large phase II clinical trial (EBL2001) as part of the EBOVAC2 consortium. Here, we perform bulk sequencing of the variable heavy chain (VH) of B cell receptors (BCR) in forty participants from the EBL2001 trial in order to characterize the BCR repertoire in response to vaccination with Ad26.ZEBOV/MVA-BN-Filo. We develop a comprehensive database, EBOV-AbDab, of publicly available Ebolavirus-specific antibody sequences. We then use our database to predict the antigen-specific component of the vaccinee repertoires. Our results show striking convergence in VH germline gene usage across participants following the MVA-BN-Filo dose, and provide further evidence of the role of IGHV3-15 and IGHV3-13 antibodies in the B cell response to Ebolavirus glycoprotein. Furthermore, we found that previously described Ebola-specific mAb sequences present in EBOV-AbDab were sufficient to describe at least one of the ten most expanded BCR clonotypes in more than two thirds of our cohort of vaccinees following the boost, providing proof of principle for the utility of computational mining of immune repertoires.

Method for B Cell Receptor Enrichment in Malignant B Cells.

B cells are central to the adaptive immune response and provide long-lasting immunity after infection. B cell activation is mediated by the surface membrane-bound B cell receptor (BCR) following recognition of a specific antigen. The BCR has been challenging to analyse using mass spectrometry (MS) due to the difficulty of isolating and enriching this membrane-bound protein complex. There are approximately 120,000 BCRs on the B cell surface; however, depending on the B cell activation state, there may be hundreds-of-millions to billions of proteins in a B cell. Consequently, advanced proteomic techniques such as MS workflows that use purified proteins to yield structural and protein-interaction information have not been published for the BCR complex. This paper describes a method for enriching the BCR complex that is MS-compatible. The method involves a Protein G pull down on agarose beads using an intermediary antibody to each of the BCR complex subcomponents (CD79a, CD79b, and membrane immunoglobulin). The enrichment process is shown to pull down the entire BCR complex and has the advantage of being readily compatible with further proteomic study including MS analysis. Using intermediary antibodies has the potential to enrich all isotypes of the BCR, unlike previous methods described in the literature that use protein G-coated beads to directly pull down the membrane IgG (mIgG) but cannot be used for other mIg isotypes.

Human B Cell Receptor Repertoire Sequencing.

Next-generation sequencing has the potential to uncover the complex nature of B cell immunity by revealing the full complexity of B cell receptor (BCR) repertoires in health and disease. However, there are drawbacks which can compromise the validity of the repertoire analysis caused by quantitative bias and accumulation of sequencing errors during the library preparation and sequencing. Here, we provide an optimized protocol designed to minimize bias for reproducible and accurate preparation of human BCR repertoire libraries for high-throughput sequencing.

B Cell Receptor Transgenic Mice as Tools to Study Memory B Cells.

B cell receptor (BCR) transgenic mice allow the control of the initial target (antigen) specificity of naïve B cells and to investigate their properties following activation. Here, I describe how BCR transgenic B cells can be used in combination with adoptive cell transfer and immunization models to study memory B cell formation and reactivation.

Lipopolysaccharide-responsive beige-like anchor is involved in regulating NF-κB activation in B cells.

Introduction: Lipopolysaccharide-responsive and beige-like anchor (LRBA) is a scaffolding protein that interacts with proteins such as CTLA-4 and PKA, the importance of which has been determined in various cell types, including T regulatory cells, B cells, and renal cells. LRBA deficiency is associated with an inborn error in immunity characterized by immunodeficiency and autoimmunity. In addition to defects in T regulatory cells, patients with LRBA deficiency also exhibit B cell defects, such as reduced cell number, low memory B cells, hypogammaglobulinemia, impaired B cell proliferation, and increased autophagy. Although Lrba-/- mice do not exhibit the immunodeficiency observed in humans, responses to B cell receptors (BCR) in B cells have not been explored. Therefore, a murine model is for elucidating the mechanism of Lrba mechanism in B cells. Aim: To compare and evaluate spleen-derived B cell responses to BCR crosslinking in C57BL6 Lrba-/- and Lrba+/+ mice. Materials and methods: Spleen-derived B cells were obtained from 8 to 12-week-old mice. Subpopulations were determined by immunostaining and flow cytometry. BCR crosslinking was assessed by the F(ab')2 anti-µ chain. Activation, proliferation and viability assays were performed using flow cytometry and protein phosphorylation was evaluated by immunoblotting. The nuclear localization of p65 was determined using confocal microscopy. Nur77 expression was evaluated by Western blot. Results: Lrba-/- B cells showed an activated phenotype and a decreased proportion of transitional 1 B cells, and both proliferation and survival were affected after BCR crosslinking in the Lrba-/- mice. The NF-κB pathway exhibited a basal activation status of several components, resulting in increased activation of p50, p65, and IκBα, basal p50 activation was reduced by the Plcγ2 inhibitor U73122. BCR crosslinking in Lrba-/ - B cells resulted in poor p50 phosphorylation and p65 nuclear localization. Increased levels of Nur77 were detected. Discussion: These results indicate the importance of Lrba in controlling NF-κB activation driven by BCR. Basal activation of NF-κB could impact cellular processes, such as, activation, differentiation, proliferation, and maintenance of B cells after antigen encounter.

Notch2 signaling governs activated B cells to form memory B cells.

Memory B cells (MBCs) are essential for humoral immunological memory and can emerge during both the pre-germinal center (GC) and GC phases. However, the transcription regulators governing MBC development remain poorly understood. Here, we report that the transcription regulator Notch2 is highly expressed in MBCs and their precursors at the pre-GC stage and required for MBC development without influencing the fate of GC and plasma cells. Mechanistically, Notch2 signaling promotes the expression of complement receptor CD21 and augments B cell receptor (BCR) signaling. Reciprocally, BCR activation up-regulates Notch2 surface expression in activated B cells via a translation-dependent mechanism. Intriguingly, Notch2 is dispensable for GC-derived MBC formation. In summary, our findings establish Notch2 as a pivotal transcription regulator orchestrating MBC development through the reciprocal enforcement of BCR signaling during the pre-GC phase and suggest that the generation of GC-independent and -dependent MBCs is governed by distinct transcriptional mechanisms.

VAV1 as a putative therapeutic target in autoimmune and chronic inflammatory diseases.

The guanine nucleotide exchange factor (GEF) VAV1, a previously 'undruggable' protein integral to T/B lymphocyte antigen-receptor signaling, promotes actin polymerization, immunological synapse formation, T cell activation and differentiation, and cytokine production. With the development of novel modalities for targeting proteins, we hypothesize that interventions targeting VAV1 will have therapeutic potential in T and T/B cell-mediated autoimmune and chronic inflammatory diseases. This opinion is supported by recent CRISPR-Cas9 studies showing VAV1 as a key positive regulator of T cell receptor (TCR) activation and cytokine production in primary human CD4+ and CD8+ T cells; data demonstrating that loss/suppression of VAV1 regulates autoimmunity and inflammation; and promising preclinical data from T and T/B cell-mediated disease models of arthritis and colitis showing the effectiveness of selective VAV1 targeting via protein degradation.

Ultrasound-Guided Fine Needle Biopsy of Human Axillary Lymph Nodes to Assess B Cell Responses to Vaccination.

Ultrasound-guided fine needle biopsy, also known as fine needle aspiration, of human axillary lymph nodes is a safe and effective procedure to assess the immune response within the lymph nodes following vaccination. Once acquired, lymph node cells can be characterized via flow cytometric immunophenotyping and/or single-cell RNA sequencing for gene expression and T and B cell receptors. Analysis of the immune cells from the lymph nodes enables the investigation of T and B cells that may interact at this site. These interactions may lead to germinal center formation and expansion, critical for the generation of effective immunity to vaccination. Directly studying the dynamic processes and interaction of the key cells has been challenging in humans due to the anatomically protected location of these cells. Here, we describe the methods involved in ultrasound-guided fine needle biopsy of human axillary lymph nodes in response to vaccination and subsequent analyses of the B cell populations.

Leveraging altered lipid metabolism in treating B cell malignancies.

B cell malignancies, comprising over 80 heterogeneous blood cancers, pose significant prognostic challenges due to intricate oncogenic signaling. Emerging evidence emphasizes the pivotal role of disrupted lipid metabolism in the development of these malignancies. Variations in lipid species, such as phospholipids, cholesterol, sphingolipids, and fatty acids, are widespread across B cell malignancies, contributing to uncontrolled cell proliferation and survival. Phospholipids play a crucial role in initial signaling cascades leading to B cell activation and malignant transformation through constitutive B cell receptor (BCR) signaling. Dysregulated cholesterol and sphingolipid homeostasis support lipid raft integrity, crucial for propagating oncogenic signals. Sphingolipids impact malignant B cell stemness, proliferation, and survival, while glycosphingolipids in lipid rafts modulate BCR activation. Additionally, cancer cells enhance fatty acid-related processes to meet heightened metabolic demands. In obese individuals, the obesity-derived lipids and adipokines surrounding adipocytes rewire lipid metabolism in malignant B cells, evading cytotoxic therapies. Genetic drivers such as MYC translocations also intrinsically alter lipid metabolism in malignant B cells. In summary, intrinsic and extrinsic factors converge to reprogram lipid metabolism, fostering aggressive phenotypes in B cell malignancies. Therefore, targeting altered lipid metabolism has translational potential for improving risk stratification and clinical management of diverse B cell malignancy subtypes.