B-cell Receptor Research Articles

Metabolomic and transcriptomic remodeling of bone marrow myeloid cells in response to maternal obesity.

Maternal obesity puts the offspring at high risk of developing obesity and cardio-metabolic diseases in adulthood. Here, we utilized a mouse model of maternal high-fat diet (HFD)-induced obesity that recapitulates metabolic perturbations seen in humans. We show increased adiposity in the offspring of HFD-fed mothers (Off-HFD) when compared to the offspring regular diet-fed mothers (Off-RD). We have previously reported significant immune perturbations in the bone marrow of newly-weaned Off-HFD. Here, we hypothesized that lipid metabolism is altered in the bone marrow of Off-HFD vs. Off-RD. To test this hypothesis, we investigated the lipidomic profile of bone marrow cells collected from three-week-old Off-RD and Off-HFD. Diacylgycerols (DAGs), triacylglycerols (TAGs), sphingolipids and phospholipids were remarkably different between the groups, independent of fetal sex. Levels of cholesteryl esters were significantly decreased in Off-HFD, suggesting reduced delivery of cholesterol. These were accompanied by age-dependent progression of mitochondrial dysfunction in bone marrow cells. We subsequently isolated CD11b+ myeloid cells from three-week-old mice and conducted metabolomics, lipidomics, and transcriptomics analyses. The lipidomic profiles of myeloid cells were similar to bone marrow cells and included increases in DAGs and decreased TAGs. Transcriptomics revealed altered expression of genes related to immune pathways including macrophage alternative activation, B-cell receptors, and TGFβ signaling. All told, this study revealed lipidomic, metabolomic, and gene expression abnormalities in bone marrow cells broadly, and in bone marrow myeloid cells particularly, in the newly-weaned offspring of mothers with obesity, which might at least partially explain the progression of metabolic and cardiovascular diseases in their adulthood.

Depletion of alloreactive B cells by drug- resistant chimeric alloantigen receptor T cells to prevent transplant rejection.

Antibody-mediated rejection (AMR) remains a major complication after solid organ transplantation (SOT). Current treatment options are inefficient and result in drastic impairment of the general immunity. To selectively eliminate responsible alloreactive B cells characterized by anti-donor-HLA B-cell receptors (BCRs), we generated T cells overcoming rejection by antibodies (CORA-Ts) engineered with a novel chimeric receptor comprising a truncated donor-HLA molecule as antigen recognition domain. As proof-of-concept, CORA receptors based on HLA-A*02 were developed. In co-cultures with anti-HLA-A*02 B-cell lines, CORA-Ts were specifically activated, released pro-inflammatory mediators, and exhibited strong cytotoxicity resulting in an effective reduction of anti-HLA-A*02 antibody release. Significant reduction of growth of an anti-HLA-A*02 B-cell line could be confirmed using an in vivo mouse model. Modification of the CORA receptor effectively abrogated T-cell binding, thereby avoiding T-cell sensitization. Additionally, using CRISPR/Cas9-mediated knockout of the FKBP12 gene, CORA-Ts were able to resist immunosuppressive treatment with tacrolimus, thereby allowing high efficiency in transplant patients. Our results demonstrate that CORA-Ts are able to specifically eliminate alloreactive, anti-HLA B cells, thus selectively preventing anti-HLA antibody release even under immunosuppressive conditions. This suggests CORA-Ts as potent approach to combat AMR and improve long-term graft survival in SOT patients while preserving their overall B-cell immunity.

An engineered immunogen activates diverse HIV broadly neutralizing antibody precursors and promotes acquisition of improbable mutations.

Elicitation of HIV broadly neutralizing antibodies (bnAbs) by vaccination first requires the activation of diverse precursors, followed by successive boosts that guide these responses to enhanced breadth through the acquisition of somatic mutations. Because HIV bnAbs contain mutations in their B cell receptors (BCRs) that are rarely generated during conventional B cell maturation, HIV vaccine immunogens must robustly engage and expand B cells with BCRs that contain these improbable mutations. Here, we engineered an immunogen that activates diverse precursors of an HIV V3-glycan bnAb and promotes their acquisition of a functionally critical improbable mutation. This immunogen was validated biochemically, structurally, and in three different humanized immunoglobulin mouse models that were designed to test HIV immunogens. These results provide a blueprint for rationally designing priming immunogens that explicitly target the elicitation of antibodies with functional yet improbable mutations.

JNK1 inhibitors target distal B cell receptor signaling and overcome BTK-inhibitor resistance in CLL.

Inhibition of the proximal B cell receptor (BCR) signaling pathway by BTK inhibitors is highly effective in the treatment of CLL, but drug resistance or intolerance occurs. Here, we investigated c-Jun N-terminal protein kinase 1 (JNK1) as an alternative drug target in the distal BCR pathway. JNK1 was preferentially overexpressed and activated in poor prognostic CLL with unmutated IGHV. Proximal BCR inhibition (BTK, PI3K, or SYK inhibitors) or SYK knockdown efficiently dephosphorylated JNK1, identifying JNK1 as a critical BCR downstream kinase in CLL. JNK1 inhibition induced apoptosis in primary CLL cells, resulting in the downregulation of BCL2, MCL1, and c-JUN. JNK1 inhibition in patient-derived CLL xenografted mice and Eµ-TCL1-tg mice prevented CLL progression, reduced splenic infiltration, and restored T cell function and normal hematopoiesis. JNK1 inhibitors even remained effective in ibrutinib refractory CLL. In conclusion, our study revealed JNK1 as a promising drug target in CLL downstream of the BCR, overcoming ibrutinib resistance, blocking the protective microenvironment, and improving CLL-specific immunosuppressive mechanisms.

SNX5 promotes antigen presentation in B cells by dual regulation of actin and lysosomal dynamics.

B cells rapidly adapt their endocytic pathway to promote the uptake and processing of extracellular antigens recognized through the B-cell receptor (BCR). The mechanisms coupling changes in endomembrane trafficking to the capacity of B cells to screen for antigens within lymphoid tissues remain unaddressed. We investigated the role of SNX5, a member of the sorting nexin family, which interacts with endocytic membranes to regulate vesicular trafficking and macropinocytosis. Our results show that in steady state, B cells form SNX5-rich protrusions at the plasma membrane, which dissipate upon interaction with soluble antigens, whereas B cells activated with immobilized antigens accumulate SNX5 at the immune synapse where it regulates actin-dependent spreading responses. B cells silenced for SNX5 exhibit enlarged lysosomes, which are not recruited to the synaptic membrane, decreasing their capacity to extract immobilized antigens. Overall, our findings reveal that SNX5 is critical for actin-dependent plasma membrane remodeling in B cells involved in antigen screening and immune synapse formation, as well as endolysosomal trafficking required to promote antigen extraction and presentation.

Expression Cloning of Antibodies from Single Human B Cells.

The majority of lymphomas originate from B cells at the germinal center stage. Preferential selection of B-cell clones by a limited set of antigens has been suggested to drive lymphoma development. While recent studies in B-cell chronic lymphocytic leukemia (CLL) have shown that self-reactive B-cell receptors (BCR) can generate cell-autonomous signaling and proliferation, our knowledge about the role of BCRs for the development or survival of other lymphomas remains limited. Here, we describe a strategy to characterize the antibody reactivity of human B cells. The approach allows for unbiased characterization of the human antibody repertoire on single-cell level through the generation of recombinant monoclonal antibodies from primary human B cells of defined origin. This protocol offers a detailed description of the method starting from the flow cytometric isolation of single human B cells to the RT-PCR-based amplification of the expressed immunoglobulin (Ig) transcripts (IGH, IGK, and IGL) and their subsequent cloning into expression vectors for the in vitro production of recombinant monoclonal antibodies. The strategy may be used to obtain information about the clonal evolution of B-cell lymphomas by single-cell sequencing of Ig transcripts and on the antibody reactivity of human lymphoma B cells.

Stereotyped B-Cell Receptor Immunoglobulins in B-Cell Lymphomas.

Thorough examination of clonotypic B-cell receptor immunoglobulin (BcR IG) gene rearrangement sequences in patients with mature B-cell malignancies has revealed significant repertoire restrictions, leading to the identification of subsets of patients expressing highly similar, stereotyped BcR IG. This discovery strongly suggests selection by common epitopes or classes of structurally similar epitopes in the development of these tumors. Initially observed in chronic lymphocytic leukemia (CLL), where the stereotyped fraction accounts for a substantial fraction of patients, stereotyped BcR IGs have also been identified in other mature B-cell malignancies, including mantle cell lymphoma (MCL) and splenic marginal zone lymphoma (SMZL).Further comparisons across different entities have indicated that stereotyped IGs are predominantly "disease-biased," indicating distinct immune pathogenetic trajectories. Notably, accumulating evidence suggests that molecular subclassification of mature B-cell malignancies based on BcR IG stereotypy holds biological and clinical relevance. Particularly in CLL, patients belonging to the same subset due to the expression of a specific stereotyped BcR IG exhibit consistent biological backgrounds and clinical courses, especially for major and extensively studied subsets. Therefore, robust assignment to stereotyped subsets may aid in uncovering mechanisms underlying disease initiation and progression, as well as refining patient risk stratification. In this chapter, we offer an overview of recent studies on BcR IG stereotypy in mature B-cell malignancies and delineate past and present methodological approaches utilized for the identification of stereotyped BcR IG.

Learning the language of antibody hypervariability

Protein language models (PLMs) have demonstrated impressive success in modeling proteins. However, general-purpose "foundational" PLMs have limited performance in modeling antibodies due to the latter's hypervariable regions, which do not conform to the evolutionary conservation principles that such models rely on. In this study, we propose a transfer learning framework called Antibody Mutagenesis-Augmented Processing (AbMAP), which fine-tunes foundational models for antibody-sequence inputs by supervising on antibody structure and binding specificity examples. Our learned feature representations accurately predict mutational effects on antigen binding, paratope identification, and other key antibody properties. We experimentally validate AbMAP for antibody optimization by applying it to refine a set of antibodies that bind to a SARS-CoV-2 peptide, and obtain an 82% hit-rate and up to 22-fold increase in binding affinity. AbMAP also unlocks large-scale analyses of immune repertoires, revealing that B-cell receptor repertoires of individuals, while remarkably different in sequence, converge toward similar structural and functional coverage. Importantly, AbMAP's transfer learning approach can be readily adapted to advances in foundational PLMs. We anticipate AbMAP will accelerate the efficient design and modeling of antibodies, expedite the discovery of antibody-based therapeutics, and deepen our understanding of humoral immunity.

Recent Progress of Irreversible BTK Inhibitors

In recent years, Bruton tyrosine kinase (BTK) inhibitors that selectively inhibit B cell receptor (BCR) signaling have become a popular and effective treatment for lymphomas in the public. As the pivotal tyrosine kinase BTK regulates the BCR pathway, BTK inhibitors were developed to block the pathway by binding with BTK thereby relieving the B-cell lymphoma progression. Ibrutinib, the first-generation BTK inhibitor, can effectively inhibit BTK and alleviate various cancer diseases. However, ibrutinib's lack of selectivity has led to a series of side effects, having adverse effects on survival rates and tolerability. By altering the molecular structure, researchers have developed the next-generation irreversible BTK inhibitors aiming at increasing target specificity and decreasing off-target impacts, such as acalabrutinib, tirabrutinib, spebrutinib, branebrutinib, and zanubrutinib, who recently received approval by FDA. This article compares and analyzes the advantages and disadvantages of these irreversible BTK inhibitors, especially zanubrutinib, with ibrutinib and finally draws a conclusion.

BTK inhibition in primary central nervous system lymphoma: mechanisms, clinical efficacy, and future perspectives.

The prognosis of primary central nervous system lymphoma (PCNSL) patients is relatively poor, and there is currently no standard treatment plan. Most patients choose high-dose chemotherapy based on methotrexate. While traditional chemotherapy combined with biological therapy has achieved limited results, some patients still do not respond to treatment or cannot tolerate its toxicity and side effects. Bruton's tyrosine kinase (BTK) is a key enzyme in B-cell receptor signaling, and its activation is critical for B-cell survival and proliferation. In recent years, BTK inhibitors have shown great potential in treating lymphomas derived from various B cells because of their strong targeting ability and relatively few side effects. They may also be a reasonable treatment choice for PCNSL. This article reviews the mechanism of action, clinical research, adverse reactions, and other issues of BTK inhibitors in treating PCNSL to provide a reference for individualized treatment of patients with PCNSL.

B Cell Receptor Repertoire Analysis of the CD21lo B Cell Compartment in Healthy Individuals, Patients With Sjögren's Disease, and Patients With Radiographic Axial Spondyloarthritis.

B cells with low or absent expression of CD21 (CD21lo B cells) gained attention due to their expansion in the peripheral blood of patients with immune-mediated, rheumatic diseases. This is not only observed in typical autoimmune diseases like systemic lupus erythematosus and Sjögren's disease (SjD) but also in radiographic axial spondyloarthritis (r-axSpA), which is considered an autoinflammatory disease. To gain more insight into the origins of the heterogeneous CD21lo B-cell population, and its relation to the plasmablast (PB) compartment, we profiled the B-cell-receptor (BCR) repertoire in CD27- and CD27+ fractions of CD21lo B cells and early PBs using next-generation sequencing. Populations were sorted from peripheral blood of healthy individuals, SjD patients, and r-axSpA patients (n = 10 for each group). In healthy individuals and both patient groups, our findings indicate that CD27-CD21lo B cells, which exhibit few mutations in their BCR, may develop into CD27+CD21lo B cells and PBs, both marked by considerably more mutations. Given the known expansion of circulating CD27-CD21lo B cells in SjD and r-axSpA patients and clonal relationships with both CD27+CD21lo B cells and early PBs, these cells might actively contribute to (pathological) immune responses in rheumatic diseases with autoimmune and/or autoinflammatory characteristics.

EXPRESSION OF IMMUNOGLOBULIN LIGHT CHAIN GENES IN STEREOTYPED CASES FROM UKRAINIAN COHORT OF CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS.

Analysis of immunoglobulin heavy chain gene (IGHV) rearrangements expressed in chronic lymphocytic leukemia (CLL) cells has provided insights into the B-cell receptor (BCR) repertoire in CLL. In more than 40% of CLL patients, (quasi)identical or stereotyped BCR is expressed. The recent data point at the non-stochastic expression of immunoglobulin light lambda (IGLV) or kappa (IGKV) chains as well. Several pairs of IGHV and IGK/LV have been described for some major stereotyped subsets, but most subsets have not been characterized. To study the IGK/LV gene expression in stereotyped CLL cases. Analysis was performed in a group of 105 CLL patients with stereotyped BCR. The cases with stereotyped BCRs were identified according to Agathangelidis et al. (2021). The IGHV and IGK/LV gene expressions were studied by a polymerase chain reaction followed by direct sequencing. The expression of the IGK/LV genes in the most presented major stereotyped subsets (#1, #2, #3C3, #4, #6, #28а) was in agreement with the data reported by other authors. For the cases of subsets #5b, #9D1, #9D4, #16, #50, #59, and #77, differences were found. The new data on the IGK/LV gene expression in 55 minor clusters were presented. A number of patterns of the IGK/LV gene expression depending on the phylogenetic clan and mutational status of the IGHV genes have been described. The non-stochastic distribution of the IGKV/LV gene expression in the individual stereotyped subsets was confirmed. Taking into account the complementary role of the light chains in antigen recognition by the clonotypic BCRs, it was suggested that the subsets with the heterogeneous IGK/LV expression might be reclassified and divided into separate subgroups based on the IGHV and IGK/LV association.

Single-cell analysis of a bi-clonal chronic lymphocytic leukemia reveals two clones with distinct gene expression pattern

Dual productive B-cell receptor (BCR) rearrangements have been repeatedly reported for chronic lymphocytic leukemia (CLL), but the standard population-based PCR analyses cannot distinguish whether these are bi-clonal CLL, or a monoclonal CLL with bi-allelic productive rearrangements. We investigated CLL cells by combined single-cell RNA and BCR sequencing. We identified two CLL clones using different immunoglobulin (Ig) heavy-chain V region genes (IGHV) genes and distinct Ig λ light chains. One clone is classified as Ig unmutated the other as mutated. The two CLL clones have distinct transcriptomes: Numerous genes were differentially expressed, with genes typical for unmutated or mutated CLL showing the expected representation in the two clones. Using PCR, cloning and Sanger sequencing of the IGHV rearrangements we detected both CLL clones over a period of three years without clinical progression of the CLL and thus giving insights into the disease biology of multi-clonal CLL.

Sequelae of B-Cell Depleting Therapy: An Immunologist's Perspective.

B-cell depleting therapy (BCDT) has revolutionised the treatment of B-cell malignancies and autoimmune diseases by targeting specific B-cell surface antigens, receptors, ligands, and signalling pathways. This narrative review explores the mechanisms, applications, and complications of BCDT, focusing on the therapeutic advancements since the introduction of rituximab in 1997. Various monoclonal antibodies and kinase inhibitors are examined for their roles in depleting B cells through antibody-dependent and independent mechanisms. The off-target effects, such as hypogammaglobulinemia, infections, and cytokine release syndrome, are discussed, emphasising the need for immunologists to identify and help manage these complications. The increasing prevalence of BCDT has necessitated the involvement of clinical immunologists in addressing treatment-associated immunological abnormalities, including persistent hypogammaglobulinemia and neutropenia. We highlight the importance of considering underlying inborn errors of immunity (IEI) in patients presenting with these complications. Furthermore, we discuss the impact of BCDT on other immune cell populations and the challenges in predicting and managing long-term immunological sequelae. The potential for novel BCDT agents targeting the BAFF/APRIL-TACI/BCMA axis and B-cell receptor signalling pathways to treat autoimmune disorders is also explored, underscoring the rapidly evolving landscape of B-cell targeted therapies.

Transcriptomic Signatures of Antibody-mediated Rejection in Early Biopsies With Negative Histology in HLA-incompatible Kidney Transplantation.

Presensitized patients with circulating donor-specific antibodies (DSAs) before transplantation are at risk for antibody-mediated rejection (AMR). Peritransplant desensitization mitigates but does not eliminate the alloimmune response. We examined the possibility that subthreshold AMR activity undetected by histology could be operating in some early biopsies. Transcriptome of kidney allograft biopsies performed within the first month in presensitized patients (DSA+) who had received desensitization and did not develop active/probable AMR by histology (R-) was compared with biopsies showing active/probable AMR (R+/DSA+). As negative controls, biopsies without rejection by histology in patients without DSA at transplantation were used (R-/DSA-). RNA sequencing from biopsies selected from the biobank was used in cohort 1 (n = 32) and microarray, including the molecular microscope (Molecular Microscope Diagnostic System [MMDx]) algorithm, in recent cohort 2 (n = 30). The transcriptome of R-/DSA+ was similar to R+/DSA+ as these groups differed in 14 transcripts only. Contrarily, large differences were found between both DSA+ groups and negative controls. Fast gene set enrichment analyses showed upregulation of the immune system in both DSA+ groups (gene ontology terms: adaptive immune response, humoral immune response, antigen receptor-mediated signaling, and B-cell receptor signaling or complement activation) when compared with negative controls. MMDx assessment in cohort 2 classified 50% of R-/DSA+ samples as AMR and found no differences in AMR molecular scores between R+ and R- DSA+ groups. In imlifidase desensitization, MMDx series showed a gradual increase in AMR scores over time. Presensitized kidney transplant recipients exhibited frequent molecular calls of AMR in biopsy-based transcript diagnostics despite desensitization therapy and negative histology.

Tertiary lymphoid structures in pancreatic cancer are structurally homologous, share gene expression patterns and B-cell clones with secondary lymphoid organs but show increased T-cell activation.

Tertiary lymphoid structures (TLS) in cancer are considered ectopic hotspots for immune activation that are similar to lymphoid follicles in secondary lymphoid organs (SLO). This study elucidates shared and TLS/SLO-specific features in pancreatic ductal adenocarcinoma (PDAC). TLS abundance was related to superior survival and T-cell abundance in 110 treatment-naïve PDAC samples, underlining their clinical relevance. Immunofluorescence microscopy identified structural homologies between TLS and SLO. In RNA-expression analyses of laser-microdissected TLS and paired SLOs, we observed largely overlapping expression patterns of immune-related gene clusters, but distinct expression patterns of T-cell and complement-associated genes. Immune cells in TLS expressed essential markers of germinal center formation. Increased activation of tumor-draining lymph nodes in patients with high numbers of TLS highlights the relevance of these tumor-related structures to systemic immune response. In line with this, we identified an overlap of expanded B-cell receptor clonotypes in TLS and SLO, which suggests a vivid cross-talk between the two compartments. . We conclude that combined therapeutic approaches exploiting TLS-mediated antitumor immune responses may improve susceptibility of PDAC to immunotherapy.

Donor HLA-DQ reactive B cells clonally expand under chronic immunosuppression and include atypical CD21 low CD27 - B cells with high-avidity germline B-cell receptors.

Long-term allograft survival is limited by humoral-associated chronic allograft rejection, suggesting inadequate constraint of humoral alloimmunity by contemporary immunosuppression. Heterogeneity in alloreactive B cells and the incomplete definition of which B cells participate in chronic rejection in immunosuppressed transplant recipients limits our ability to develop effective therapies. Using a double-fluorochrome single-HLA tetramer approach combined with single-cell in vitro culture, we investigated the B-cell receptor (BCR) repertoire characteristics, avidity, and phenotype of donor HLA-DQ reactive B cells in a transplant recipient with end-stage donor specific antibody (DSA)-associated cardiac allograft vasculopathy while receiving maintenance immunosuppression (tacrolimus, mycophenolate mofetil, prednisone). Donor DQB1*03:02/DQA1*03:01 (DQ8)-reactive IgG+ B cells were enriched for minimally mutated and germline encoded high avidity BCRs (median K D 4.26×10 -09 ) with an atypical, antigen-experienced and proliferative phenotype (CD27 - CD21 low CD71 + CD11c +/- ). These B cells coexisted with a smaller subset of more highly mutated, affinity matured IgG+CD27+ B cells. Circulating donor-reactive B cells and DSA remained detectable after rituximab, contrasting with the marked reduction in DSA after allograft explant and retransplant. Together, these findings define the persistence of germline high-avidity HLA-DQ alloreactive B cells and their co-existence with affinity matured clones that were both driven by the allograft despite conventional immunosuppression.

Risk-stratification in frontline CLL therapy: standard of care.

The treatment of chronic lymphocytic leukemia (CLL) has been transformed over the past decade based on a better understanding of disease biology, especially regarding molecular genetic drivers and relevant signaling pathways. Agents focusing on B-cell receptor (in particular Bruton tyrosine kinase [BTK]) and apoptosis (BCL2) targets have replaced chemoimmunotherapy (CIT) as the treatment standard. BTK and BCL2 inhibitor-based therapy has consistently shown prolonged progression-free survival and in some instances even increased overall survival against CIT in frontline phase 3 trials. This improvement is particularly pronounced in high-risk CLL subgroups defined by unmutated IGHV, deletion 17p (17p-), and/or the mutation of TP53, making CIT in these subgroups essentially obsolete. Despite remarkable advances, these markers also retain a differential prognostic and predictive impact in the context of targeted therapies, mandating risk-stratification in frontline management. Furthermore, BTK- and BCL2-targeting agents differ in their adverse event profiles, requiring adjustment of treatment choice based on patient characteristics such as coexisting conditions, comedications, and delivery-of-care aspects.

Aberrantly Expressed Mitochondrial Lipid Kinase, AGK Activates JAK2-Histone H3 Axis and BCR Signal: A Mechanistic Study with Implication in CLL Therapy.

Although the B-cell receptor (BCR) signal plays a critical role in CLL cell survival and a target of current therapies (ibrutinib targets Bruton's tyrosine kinase; idelalisib targets PI3Kδ), contribution of the cytokine-driven JAK2 pathway to the "CLL cell-survival signaling network" is largely undefined. CLL patients were enrolled to investigate expression/activation of JAK2 and acylglycerol kinase (AGK), and their functional implication in primary CLL cell survival. A series of biochemical and molecular biology assays were employed to uncover the underlying mechanism. We detected that compared to normal B-cells, CLL cells aberrantly express constitutively active JAK2. Mechanistically, HSP90 forms a chaperoning complex with JAK2, resulting in its aberrant accumulation in CLL cells. We also discovered aberrant upregulation of a novel mitochondrial lipid kinase, AGK, which remains complexed with HSP90 in CLL cells activating JAK2. Although AGK is typically mitochondrial, we detected its nuclear localization in association with JAK2 in some CLL cells. Functionally, JAK2 phosphorylates its non-canonical substrate, histone H3(Y41), but not STAT3, activating transcription of diverse sets of genes in a patient-specific manner. Additionally, JAK2 activates the BCR-signal in CLL cells via LYN/BTK axis. Targeted inhibition of JAK2 as monotherapy, or in combination with the BCR-inhibitors or venetoclax (a BCL2-inhibitor) induced apoptosis synergistically in CLL cells. These findings suggest that aberrantly expressed AGK activates JAK2, independent of cytokine, leading to activation of diverse sets of gene transcription in CLL cells. Combined targeting of JAK2 and BCR signals or BCL2 may be effective in some CLL patients.

In vivo affinity maturation of the CD4 domains of an HIV-1-entry inhibitor.

Human proteins repurposed as biologics for clinical use have been engineered through in vitro techniques that improve the affinity of the biologics for their ligands. However, the techniques do not select against properties, such as protease sensitivity or self-reactivity, that impair the biologics' clinical efficacy. Here we show that the B-cell receptors of primary murine B cells can be engineered to affinity mature in vivo the human CD4 domains of the HIV-1-entry inhibitor CD4 immunoadhesin (CD4-Ig). Specifically, we introduced genes encoding the CD4 domains 1 and 2 (D1D2) of a half-life-enhanced form of CD4-Ig (CD4-Ig-v0) into the heavy-chain loci of murine B cells and adoptively transferred these cells into wild-type mice. After immunization, the B cells proliferated, class switched, affinity matured and produced D1D2-presenting antibodies. Somatic hypermutations in the D1D2-encoding region of the engrafted cells improved the binding affinity of CD4-Ig-v0 for the HIV-1 envelope glycoprotein and the inhibitor's ability to neutralize a panel of HIV-1 isolates without impairing its pharmacokinetic properties. In vivo affinity maturation of non-antibody protein biologics may guide the development of more effective therapeutics.