B-cell Clones Research Articles

B-cell Clonality in HCV-Induced Patients Treated with Oral Direct-Acting Antiviral Agents.

Hepatitis C virus (HCV) is a worldwide' health problem as Egypt has a very high prevalence (14.7%) that may affect the B-Lymphocytes, and in some cases leading to an expansion of monoclonal B-cell detected by immunoglobulin heavy chain (IgH) gene rearrangement. Therefore, we aimed to assess the occurrence of IgH gene rearrangement in Egyptian chronic HCV patients and studying the effect of oral direct-acting antiviral (DAAs) therapy on regression of the clonality markers. 78 Egyptian patients with chronic HCV infection were included in this study and polymerase chain reaction (PCR) analysis was used to detect IgH rearrangement based on standardized PCR protocols of the BIOMED-2 international guidelines study. Clonal IgH showed a significant increase of HCV-RNA expression and correlated with increased alanine transaminase (ALT) in all patients, while a significant increase of kappa and lambda free light chain observed only in clonal IgH with lymphoproliferative disorders (LPD) patients. A total of 37.17% (29/78) IgH clonality was detected in all patients (7.69% with LPD and 29.48% without LPD). 37% of these IgH clonality disappeared with HCV eradication after DAAs regimen. we concluded that different DAAs regimen with or without RBV is safe and effective for the treatment of Egyptian patients, but its effect is partially and not completely in the eradication of IgH clonality. Also, using IgH rearrangement in patients with chronic HCV is helpful as indicator in patients at high risk for prediction of LPD.

Risk of incident melanoma among individuals with low-count monoclonal B-cell lymphocytosis (MBL).

7577 Background: Prior research has consistently shown that patients with chronic lymphocytic leukemia (CLL) have an ~2-fold increased risk of developing melanoma compared to controls. MBL is a common condition affecting 8-10 million adults over the age of 40 years in the United States and is a precursor to CLL. Little is known about the association between MBL and melanoma. Herein, we evaluated the risk of incident melanoma in a large cohort of individuals screened for MBL. Methods: Participants from the Mayo Clinic Biobank who had no prior history of hematologic malignancy, were 40 years or older, were residents of counties surrounding Mayo Clinic, and who provided blood samples between 7/2009 and 4/2022 were included in the study. Peripheral blood mononuclear cells were screened for MBL using highly sensitive eight-color flow cytometry. Individuals with MBL were classified as CLL-like MBL (CD5+, CD20dim) or atypical MBL (CD5+, CD20+) based on immunophenotypes, and also classified as low-count MBL (LCMBL) or high-count MBL (HCMBL) based on whether the percent clonal B-cell count was < 85% or ≥85%, respectively. Diagnosis of melanoma was ascertained using ICD codes and review of the electronic health records. All individuals were followed from date of sample upon which MBL screening was performed to the earliest of incident melanoma, loss to follow-up, withdrawal from the study, or September 30, 2022. We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI), adjusting for age, sex, and history of melanoma in previous 5 years. Results: A total of 7,334 participants were screened for MBL, of which 1,151 (16%) individuals had MBL. Among those with MBL, 1,107 (96.2%) had CLL-like MBL and 1098 (95.4%) had LC MBL. The median age at entry into the MBL screening cohort was 67 years (range 40-101) and 37% were male; individuals with MBL were older (median age 72 vs 65 years) and male (49% vs 35%). After a median follow-up of 2.9 years (range 0-13.2), 121 of the 7,334 (1.6%) participants developed incident melanoma after the date of MBL screening. The 10-year cumulative incidence of melanoma among individuals with MBL was 7.8% (95% CI 4.5-13.5%) compared to 3.4% (2.7-4.4%) in those who screened negative for MBL. After adjusting for age, sex, and history of prior melanoma, we found a 1.81-fold increased risk of incident melanoma (95% CI 1.19-2.76) among individuals with MBL. The increased risk of melanoma persisted when the analysis was restricted to individuals with LCMBL (HR = 1.84; 95% CI 1.21-2.82). Conclusions: In the largest MBL screening cohort to date, we found that LCMBL, a common condition, was associated with an 84% elevated risk of melanoma, similar to the ~2-fold increased risk observed in patients with CLL. These data, together with our prior findings of a heightened risk of serious infections and lymphoid malignancies, suggest that individuals with LCMBL are at increased risk for adverse health outcomes.

Cold Agglutinin Disease – Diagnostic and Therapeutic Challenges in the Clinical Setting

Cold agglutinin disease (CAD) is a rare form of autoimmune hemolytic anemia (AIHA), in which IgM specific antibodies cause the agglutination of red blood cells (RBCs) at temperatures < 37°C and activate the classical pathway of complement leading to extravascular hemolysis, C3b-coated RBCs are phagocytosed by the macrophages of the reticuloendothelial system (predominantly in the liver). Up to date there are two clinical-pathologic entities recognized as distinct with different therapeutic implications: cold agglutinin disease and cold agglutinin syndrome (CAS). Primary CAD is recognised as clonal B-cell lymphoproliferative disorder of the bone marrow, clinical and imagistic evidence of associated malignancy. CAS arises in the setting of an underlying disorder such as infection, autoimmune disease or malignancy (non Hodgkin lymphoma or other malignant process). The diagnosis of CAD is often delayed due to the unpredictable clinical course. In spite of the current therapeutic options which are directed at the pathogenic B cells or the complement system, the low response rates and frequent relapses lead to challenges regarding the management of this disease.

Dynamic changes in circulating EBV-DNA load during treatment have prognostic values in EBV+ DLBCL-NOS: a Chinese cohort study.

EBV-positive diffuse large B-cell lymphoma, not otherwise specified (EBV+ DLBCL-NOS), is an EBV-positive clonal B-cell lymphoid proliferation and circulating EBV-DNA is a great indicator for prognosis among EBV associated disease. In this retrospective study, we report 66 EBV+ DLBCL cases among 2137 DLBCL-NOS cases diagnosed from 2013 to 2021 (prevalence of 6.0%). After a median follow-up of 27months, progression-free survival (PFS) and overall survival (OS) at 2years were 39.5% ± 6.2% and 53.6% ± 6.4%, respectively. Multivariate analysis showed that only the biomarker of the positivity of post treatment EBV-DNA had a borderline correlation with shorter PFS and OS (PFS: P = 0.053; OS: P = 0.065). Patients were divided into three subgroups according to dynamic changes of EBV-DNA status: EBV-DNA persistently negative group, EBV-DNA persistently positive group, and EBV-DNA transformed from positive to negative group; among the three groups, patients of the persistently positive group had worst PFS and OS (P = 0.0527 and P = 0.0139, respectively). Decline in EBV copies correlated significantly with treatment response as well. In conclusion, circulating EBV-DNA level played a vital role in prognostic and monitoring marker for EBV+ DLBCL-NOS.

Monoclonal gammopathies of renal significance

The term monoclonal gammopathies of renal significance (MGRS) encompasses a group of renal histopathological lesions fulfilling two criteria: (a) they are caused by nephrotoxic monoclonal immunoglobulins and (b) the monoclonal immunoglobulins are produced by small B-cell or plasma cell clones which do not meet the criteria for multiple myeloma or malignant lymphoma. Here, we provide a review of the MGRS definition and related terminology and elaborate on the diagnostic approach and treatment principles from the general physician perspective.

Primary EBV Lymphoproliferative Disease Responsive to Therapy in a Patient with CTLA4-Haploinsufficiency

Epstein-Barr virus lymphoproliferative disease (EBV-LPD) occurs most often in patients with acquired immunosuppression. However, several inborn errors of immunity have been associated with primary EBV-LPD, including pathogenic variants in SH2D1A, ITK, MAGT1, CORO1A, CD27, CTPS1, RASGRP1, and ZAP70 (PMID29942301,34239742). Here, we present a patient with primary EBV-LPD in the setting of CTLA-4 haploinsufficiency. JC is a 25yo male with Evans syndrome, hypogammaglobulinemia, and central nervous system vasculitis who presented to the NIH for evaluation of EBV-LPD. After a complicated course of legionella pneumonia at age 23, he developed recurrent fevers, respiratory distress, hypoxia, and night sweats responsive to dexamethasone. Chest CT revealed innumerable bilateral pulmonary nodules and masses with mediastinal hilar lymphadenopathy and scattered ground glass opacities. Transbronchial biopsy demonstrated EBV-positive B-cell LPD with extensive necrosis and clonal gene rearrangements. He responded well to 1 cycle of rituximab. Two years later, he again had fever, dyspnea on exertion, and hypoxia requiring glucocorticoids. Chest CT revealed ground glass opacities of the lungs, lung nodules/masses, and consolidation. Lung biopsy showed T and B-cell infiltrates, EBV+ B-cells by immunohistochemistry, and a clonal B-cell population (Figure 1). His course was also complicated by concurrent Pneumocystis Jirovecii (PJP) infection. He received 1 cycle of rituximab, trimethoprim-sulfamethoxazole, and sirolimus for treatment of his EBV-LPD, PJP, and underlying CTLA-4 haploinsufficiency respectively with symptomatic and radiologic response (Figure 2). [Display omitted] [Display omitted] NIAID whole exome sequencing (WES) revealed 2 compound heterozygous variants in CTLA-4 in trans: a novel pathogenic variant c.373G > A, p.Gly125Arg, and a non-pathogenic c.326G > A, p.Gly109Glu, shared with his mother(allele frequency of 0.000367 popmaxv.3.1.1 and Cadd score 17). Other variants that may contribute to EBV-LPD are under investigation.EBV-LPD in CTLA-4 haploinsufficiency is rare, previously reported in only 2 pediatric cases (PMID34329649). Additionally, WES revealed compound heterozygous variants in CTLA-4; however, only 1 variant was proven pathogenic. While this patient initially demonstrated excellent response to first line therapy, long-term prognosis is guarded. Abatacept was not included in this patient’s treatment because of an association with progressive LPD in patients with and without CTLA-4 haploinsufficiency. Immune reconstitution with bone marrow transplantation will likely be required for permanent disease control.

The Synthetic Collagen-Binding Peptide NIPEP-OSS Delays Mouse Myeloma Progression.

Multiple myeloma (MM) is the second most common hematological malignancy. It is a clonal B-cell disorder characterized by the proliferation of malignant plasma cells in the bone marrow, the presence of monoclonal serum immunoglobulin, and osteolytic lesions. An increasing amount of evidence shows that the interactions of MM cells and the bone microenvironment play a significant role, suggesting that these interactions may be good targets for therapy. The osteopontin-derived collagen-binding motif-bearing peptide NIPEP-OSS stimulates biomineralization and enhances bone remodeling dynamics. Due to its unique targeted osteogenic activity with a broad safety margin, we evaluated the potential of NIPEP-OSS for anti-myeloma activity using MM bone disease (MMBD) animal models. In a 5TGM1-engrafted NSG model, the survival rates of the control and treated groups were significantly different (p = 0.0014), with median survival times of 45 and 57 days, respectively. The bioluminescence analyses showed that myeloma slowly developed in the treated mice compared to the control mice in both models. NIPEP-OSS enhanced bone formation by increasing biomineralization in the bone. We also tested NIPEP-OSS in a well-established 5TGM1-engrafted C57BL/KaLwRij model. Similar to the previous model, the median survival times of the control and treated groups were significantly different (p = 0.0057), with 46 and 63 days, respectively. In comparison with the control, an increase in p1NP was found in the treated mice. We concluded that NIPEP-OSS delays mouse myeloma progression via bone formation in MMBD mouse models.

Early B cell tolerance defects in anti-neurofascin 155 mediated chronic inflammatory demyelinating polyneuropathy (S40.005)

Early B cell tolerance defects in anti-neurofascin 155 mediated chronic inflammatory demyelinating polyneuropathy (S40.005)

The choice of new treatments in autoimmune hemolytic anemia: how to pick from the basket?

Autoimmune hemolytic anemia (AIHA) is defined by increased erythrocyte turnover mediated by autoimmune mechanisms. While corticosteroids remain first-line therapy in most cases of warm-antibody AIHA, cold agglutinin disease is treated by targeting the underlying clonal B-cell proliferation or the classical complement activation pathway. Several new established or investigational drugs and treatment regimens have appeared during the last 1-2 decades, resulting in an improvement of therapy options but also raising challenges on how to select the best treatment in individual patients. In severe warm-antibody AIHA, there is evidence for the upfront addition of rituximab to prednisolone in the first line. Novel agents targeting B-cells, extravascular hemolysis, or removing IgG will offer further options in the acute and relapsed/refractory settings. In cold agglutinin disease, the development of complement inhibitors and B-cell targeting agents makes it possible to individualize therapy, based on the disease profile and patient characteristics. For most AIHAs, the optimal treatment remains to be found, and there is still a need for more evidence-based therapies. Therefore, prospective clinical trials should be encouraged.

Kidney Transplantation in Patients With Monoclonal Gammopathy of Renal Significance.

Monoclonal gammopathy of renal significance (MGRS) defines disorders characterized by direct or indirect kidney injury caused by a monoclonal immunoglobulin produced by a B-cell or plasma-cell clone that does not meet current hematologic criteria for therapy. MGRS-associated kidney diseases are diverse and can result in the development of end-stage kidney disease. The current paradigm states that the underlying hematologic condition should be treated and in deep remission before kidney transplantation can be performed because recurrence has been reported for all MGRS-associated kidney diseases. However, we suggest that decisions regarding kidney transplantation in MGRS patients should be individualized considering many factors such as the subtype of MGRS-associated kidney disease, patient age and comorbidity, presence and risk of extrarenal complications, estimated waiting time, the availability of a living kidney donor, and previous hematological treatment and response. Thus, kidney transplantation should be considered even in treatment-naive patients, with hematological treatment initiated after successful kidney transplantation.

Insights into B-cell ontogeny inferred from human immunology.

Due to ontogenetic changes in B-cell developmental lineages, the mature B-cell compartment constitutes by functionally different B-cell subsets that emerged from prenatal, early postnatal or adult precursors. While negative selection processes operate primarily within the framework of B-cell tolerance checkpoints during B-cell development, further differentiation into distinct B-cell subsets is additionally induced by positive selection. In addition to endogenous antigens, contact with microbial antigens is also involved in this selection process, with intestinal commensals having a significant influence on the development of a large layer within the B-cell compartment. The decisive threshold that triggers negative selection seems to be relaxed during fetal B-cell development, thereby allowing recruitment of polyreactive and also autoreactive B-cell clones into the mature naïve B-cell compartment. Almost all of the concepts on B-cell ontogeny are based on observations in laboratory mice that not only differ from humans in their developmental timeline but also in their composition of commensal microorganisms or rather a lack of exposure to these. In this review, we summarize conceptual findings on B-cell ontogeny and particularly describe key insights into the developing human B-cell compartment and immunoglobulin repertoire formation.

Abstract 5222: Genetic variants associated with progression from monoclonal B-cell lymphocytosis (MBL) to chronic lymphocytic leukemia (CLL)

Abstract Low count (LC) MBL is characterized by a circulating population of clonal B-cells and is a precursor state to CLL. Most individuals with LC MBL do not progress to CLL and never come to clinical attention. An active area of research is to identify factors that distinguish those individuals with MBL who progress from those who do not. Currently, 41 single nucleotide polymorphisms (SNPs) are known to be associated with CLL risk, and a portion of these SNPs have also been found to be associated with MBL risk. We hypothesize that these CLL-susceptibility SNPs associated with both MBL and CLL risk are SNPs associated with developing a B-cell clone; whereas the remaining SNPs found not to be associated with MBL risk are associated with progression of the B-cell clone (i.e., progression from MBL to CLL). To test this hypothesis, we evaluated the association of these 41 SNPs with risk of progression to CLL using a case-control study of 1,911 CLL cases and 1,579 individuals with MBL from Mayo Clinic. Individuals with MBL were identified through screening using 8-color flow cytometry assay. Individuals with LC MBL (defined by having a clonal B-cell population with the percent clonal B-cells out of total B-cell count <85%) who had an immunophenotype consistent with CLL were included as controls. CLL cases were obtained through the Mayo Clinic hematology practice. DNA was genotyped from whole blood. We analyzed the 41 CLL susceptibility SNPs with risk of progression to CLL using logistic regression and estimated odds ratio (OR) and 95% confidence interval (CI), adjusting for sex and age. We evaluated the CLL polygenic risk score (CLL-PRS), comprised of a weighted average of the 41 SNPs, with risk of CLL. Out of the 41 established CLL susceptibility SNPs, 15 were associated with CLL progression from MBL to CLL (all P<0.05). Nine of these 15 significant SNPs were not previously found to be associated with risk of MBL. The most significant SNPs were rs9880772 (OR=1.23, CI: 1.11-1.36, P=6.1 × 10−5), rs888096 (OR=1.25, CI: 1.12-1.38, P=3.0 × 10−5), and rs305065 (OR=1.28, CI: 1.14-1.43, P=1.5 × 10−5). One SNP (rs77551289) had a suggestive association (OR=1.21, P=0.069). The remaining 25 SNPs had no evidence of association with progression (ORs ranging between 0.9-1.1 and all P>0.1). The CLL-PRS was also associated with CLL risk (continuous OR = 1.25, CI: 1.15 - 1.35, P = 6.7 × 10−8). In our study accounting for the presence of B-cell clonal population, we identified 15 out of 41 CLL-susceptibility SNPs to be significantly associated with progression from LC MBL to CLL. The remaining 25 non-significant CLL-SNPs were not associated with progression and may instead be associated with development or initiation of the B-cell clone. These findings suggest that the established CLL susceptibility SNPs may play differing role (i.e., development or progression of the clone) in the etiology of CLL. Citation Format: Raphael Mwangi, Geffen Kleinstern, Sara J. Achenbach, Dennis Robinson, Aaron D. Norman, Kari G. Rabe, Janet E. Olson, Neil E. Kay, Rosalie G. Waller, Nicholas J. Boddicker, James R. Cerhan, Esteban Braggio, Sameer A. Parikh, Curtis A. Hanson, Celine M. Vachon, Tait Shanafelt, Susan L. Slager. Genetic variants associated with progression from monoclonal B-cell lymphocytosis (MBL) to chronic lymphocytic leukemia (CLL). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5222.

Abstract 2269: Bexmarilimab induces B-cell activation and autoantibody production

Abstract Introduction: Bexmarilimab, a Clever-1 targeting humanized antibody, is a macrophage checkpoint inhibitor promoting antigen presentation and pro-inflammatory cytokine secretion. Data from the first-in-human clinical Phase I/II study (MATINS; NCT03733990) demonstrate that single agent bexmarilimab is able to ignite an interferon response with survival benefit in 30% of patients with advanced gastric cancer, cutaneous melanoma and cholangiocarcinoma (ASCO 2022). Since Clever-1 knockout mice have been reported to have enhanced T-cell antibody production and bexmarilimab increases peripheral B-cell populations, we investigated B-cell phenotype, clonality and autoantibody formation in bexmarilimab treatmented MATINS patients. Methods: We first performed comprehensive phenotyping of peripheral B-cells from a colorectal carcinoma patient showing partial response (per RECIST v1.1). Autoantibody reactivities were measured in 80 serum samples of bexmarilimab treated patients (37 pre-treatment and 43 post-treatment samples from cycles 3 and 4) and compared to serums from 53 healthy individuals using Oncimmune's SeroTag multiplex technology with an immune-oncology (IO) specific protein array comprised of 1162 antigens. Results: Single-cell sequencing together with BCR sequencing of the responder’s B-cells during cycle 4 revealed an induced and activated B-cell population consisting of four transcriptionally similar clusters expressing IGHM, IGHD, CD23 but not CD43 and one cluster expressing CD79B, PLD4 and MZB1, which was distant from the naïve CCR7 expressing B-cells and IGHA1 and IGHG1 expressing plasma blasts. The expansion of B-cells was not due to clonal expansion as no overlapping BCR clones were identified between B-cells at pre-dose and cycle 4. Autoantibody profiling revealed great inter-individual heterogeneity in the number and targets of induced antibodies among patients treated with bexmarilimab reflecting individual patterns in self- and tumor antigens. However, shared autoantibody changes against targets such as cancer testis antigens (GAGE2), typical autoimmune disease antigens (SNRPC, TPO, TOP1) and antigens related to the induction of innate immunity and interferon responses, e.g. TRIM21 were observed. Importantly, we identified a set of pre-treatment autoantibodies that were associated with longer time to disease progression and were predictive of clinical response (disease control rate [DCR], consisting of CR, PR, SD) and progression-free survival (PFS) on bexmarilimab therapy. Conclusions: Our data implies that bexmarilimab can induce activation and secondary Ig rearrangements in mature B-cells, which has been reported to occur in germinal centres during T-cell dependent antibody responses to increase B-cell diversity and affinity of antigen receptors. B cell diversity and activation was reflected in patient autoantibody production and may enhance cancer immune recognition. Citation Format: Elisa M. Vuorinen, Mari L. Björkman, Reetta Virtakoivu, Juho Jalkanen, Sofia Aakko, Akira Takeda, Petra Budde, Hans-Dieter Zucht, Manuel Brautigam, Behnaz Ahangarianabhari, Petri Bono, Maija Hollmén. Bexmarilimab induces B-cell activation and autoantibody production [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2269.

Abstract 779: Clonal B-cell expansion and the potential challenges to blood-based early cancer detection

Abstract Introduction: Confounding signals originating from white blood cells (WBCs) have been reported as a potential source of false positives for blood-based early cancer detection and disease monitoring. Additionally, the level of aberrant signal originating from clonal expansion (CE) in precursor conditions, such as monoclonal B-cell lymphocytosis (MBL) and monoclonal gammopathy of undetermined significance (MGUS), is not well understood. To characterize CE in a potential screening population, we profiled samples from non-cancer (NC) participants and compared them to samples from participants with hematological precursor and neoplastic conditions (HPNCs). Methods: Using LymphoTrack IGH FR1 Assay (Invivoscribe, Inc), we sequenced DNA derived from WBCs from a subset of enrollees in the Circulating Cancer Genome Atlas study (NCT02889978) comprising NC participants, balanced for age and gender, and participants diagnosed with an HPNC (chronic lymphocytic leukemia [CLL], multiple myeloma [MM], MBL, or MGUS). Additional samples were titrated and processed to determine the limit of quantification (LoQ). Results: Using 12 titration samples, we determined the LoQ of detecting an unknown clone against a polyclonal background to be 0.1% of the total reads. The threshold used to determine evidence of CE was 2.5% of the total reads. We sequenced samples from 112 individuals, 67 of whom were NC participants (35 male of median [range] age 67 [33-85] years; 32 female of 60 [30-85] years). A large fraction of NC samples (10/67; 15%) showed evidence of CE: 9/10 (90%) were monoclonal with clonal percent total reads (PTR) ranging from 2.7% to 80.4% (median: 6.0%), and 7/9 had a mutation rate >2%, indicating somatic hypermutation (SHM). One sample exhibited oligoclonality with 2 clones (6.6% and 3.2%), and both had SHM. Most NC samples (57/67; 85%) lacked evidence of CE: median top clone PTR of 0.10% (mean: 0.18%; SD: 0.24%) and median Simpson clonality of 0.0021 (mean: 0.0030; SD: 0.0030). A positive correlation between the top clone PTR and age was also observed (⍴=0.41 all participants, ⍴=0.43 excluding 80.4% PTR). All CLL samples (9/11 monoclonal; 2/11 oligoclonal) and 3/4 MBL samples showed evidence of CE. Consistent with the observation that a limited number of plasma cells are expected to be in circulation, only 3/10 MM samples and 7/20 MGUS samples showed evidence of CE; 1 MM and 3 MGUS samples had a top clone PTR of >40%. Conclusion: A large fraction of NC samples (15%) had evidence of expanded lymphoid clones with SHM. The PTR of the top clone underscores the higher frequency of CE associated with increased age in asymptomatic participants. Clonal expansion of blood cell lineages can also carry genetic or epigenetic alterations that are similar to those associated with non-hematologic cancers. Thus, differentiating aberrant signals originating from various hematologic compartments is key for accurate early cancer detection. Citation Format: Jing Xiang, Qinwen Liu, Rita Shaknovich, Oliver Venn. Clonal B-cell expansion and the potential challenges to blood-based early cancer detection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 779.

Monoclonal B-cell lymphocytosis with a non-CLL immunophenotype - Review of 34 cases.

The monoclonal B-cell lymphocytosis (MBL) introduced as new entities in the 2008 WHO classification, are defined by circulating B-cell clone <5.109/L without organomegaly and previous and/or simultaneous lymphoproliferative disorders. The MBL were subclassified in MBL CLL type (the most frequent), MBL atypical CLL type and MBL non-CLL type (rarely reported in literature). Here the clinic, cytologic, immunologic and genetic features of MBL non-CLL type were described from a series of 34 cases. As previously reported, present cases presented immunologic and genetic similarities to MZL and could be associated to the new proposed entity CBL-MZ (clonal B-cell lymphocytosis of marginal zone origin). In addition, few cases presented similarities to splenic diffuse red pulp lymphoma (SDRPL). In conclusion, according to the literature, MBL with non-CLL type (assimilated to CBL-MZ) may be a premalignant state of MZL and/or SDRPL.

T follicular helper cell responses to SARS-CoV-2 vaccination among healthy and immunocompromised adults.

The worldwide rollout of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinations in the last 2 years has produced a multitude of studies investigating T-cell responses in the peripheral blood and a limited number in secondary lymphoid tissues. As a key component to an effective immune response, vaccine-specific T follicular helper (Tfh) cells are localized in the draining lymph node (LN) and assist in the selection of highly specific B-cell clones for the production of neutralizing antibodies. While these cells have been noted in the blood as circulating Tfh (cTfh) cells, they are not often taken into consideration when examining effective CD4+ T-cell responses, particularly in immunocompromised groups. Furthermore, site-specific analyses in locations such as the LN have recently become an attractive area of investigation. This is mainly a result of improved sampling methods via ultrasound-guided fine-needle biopsy (FNB)/fine-needle aspiration (FNA), which are less invasive than LN excision and able to be performed longitudinally. While these studies have been undertaken in healthy individuals, data from immunocompromised groups are lacking. This review will focus on both Tfh and cTfh responses after SARS-CoV-2 vaccination in healthy and immunocompromised individuals. This area of investigation could identify key characteristics of a successful LN response required for the prevention of infection and viral clearance. This furthermore may highlight responses that could be fine-tuned to improve vaccine efficacy within immunocompromised groups that are at a risk of more severe disease.

Cladribine treatment specifically affects peripheral blood memory B cell clones and clonal expansion in multiple sclerosis patients.

B cells are acknowledged as crucial players in the pathogenesis of multiple sclerosis (MS). Several disease modifying drugs including cladribine have been shown to exert differential effects on peripheral blood B cell subsets. However, little is known regarding functional changes within the peripheral B cell populations. In this study, we obtained a detailed picture of B cell repertoire changes under cladribine treatment on a combined immunoglobulin (Ig) transcriptome and proteome level. We performed next-generation sequencing of Ig heavy chain (IGH) transcripts and Ig mass spectrometry in cladribine-treated patients with relapsing-remitting multiple sclerosis (n = 8) at baseline and after 6 and 12 months of treatment in order to generate Ig transcriptome and Ig peptide libraries. Ig peptides were overlapped with the corresponding IGH transcriptome in order to analyze B cell clones on a combined transcriptome and proteome level. The analysis of peripheral blood B cell percentages pointed towards a significant decrease of memory B cells and an increase of naive B cells following cladribine therapy. While basic IGH repertoire parameters (e.g. variable heavy chain family usage and Ig subclasses) were only slightly affected by cladribine treatment, a significantly decreased number of clones and significantly lower diversity in the memory subset was noticeable at 6 months following treatment which was sustained at 12 months. When looking at B-cell clones comprising sequences from the different time-points, clones spanning between all three time-points were significantly more frequent than clones including sequences from two time-points. Furthermore, Ig proteome analyses showed that Ig transcriptome specific peptides could mostly be equally aligned to all three time-points pointing towards a proportion of B-cell clones that are maintained during treatment. Our findings suggest that peripheral B cell related treatment effects of cladribine tablets might be exerted through a reduction of possibly disease relevant clones in the memory B cell subset without disrupting the overall clonal composition of B cells. Our results -at least partially- might explain the relatively mild side effects regarding infections and the sustained immune response after vaccinations during treatment. However, exact disease driving B cell subsets and their effects remain unknown and should be addressed in future studies.

Mature B-Cell Neoplasms with Immunophenotypically Distinct Dual B-Cell Clones: A Case Series

Mature B-Cell Neoplasms with Immunophenotypically Distinct Dual B-Cell Clones: A Case Series

A SYSTEMIC REVIEW COVID-19 VACCINE

One of the biggest issues facing the world now is the COVID-19 epidemic. Since there was neither a specific treatment nor a specific vaccine at the time, various pharmaceutical companies—particularly Indian pharmaceutical companies—started developing an effective COVID-19 vaccine. There are many different types of vaccines, including those based on DNA, mRNA, R-DNA technology, proteins, and inactivated viruses-based vaccines. These vaccines are all made by an Indian pharmaceutical business. Following the development, the Indian Council of Medical Research (ICMR), the Drug Controller General of India (DCGI), the Food and Drug Administration, and the WHO approved the use of the vaccine for clinical trials and emergencies. After three trials, an Indian-made vaccine shows high efficacy. The fundamental function of the vaccine is to activate CD8+ cytotoxic T-cells and trigger B-cell clone growth. Lead cytogeneses IL-5 and IL-4 promote IgG antibodies, which strengthen our protection against COVID-19 and its variations.

Sialylation regulates migration in chronic lymphocytic leukemia.

Sialylation is the terminal addition of sialic acid to underlying glycans. It plays a prominent role in cell adhesion and immune regulation. Sialylated structures found on adhesion molecules, such as CD49d, mediate the interactions between cancer cells and the microenvironment, facilitating metastatic seeding in target organs. Chronic lymphocytic leukemia (CLL) is a clonal B-cell malignancy characterized by the accumulation of CD5-positive B cells in the peripheral blood, bone marrow and lymph nodes. CLL cells proliferate mainly in the lymph node "proliferation centers", where the microenvironment provides pro-survival signals. Thus, migration and homing into these protective niches play a crucial role in CLL biology. In recent years, therapeutic strategies aimed at inducing the egress of CLL cells from the lymph nodes and bone marrow into the circulation have been highly successful. In this study, the sialylation status of 79 untreated and 24 ibrutinib-treated CLL patients was characterized by flow cytometry. Moreover, the effect of sialic acid removal on migration was tested by a transwell assay. Finally, we examined the sialylation status of CD49d by Western blot analysis. We found that CLL cells are highly sialylated, particularly those characterized by an "activated" immune phenotype. Notably, sialylation regulates CLL migration through the post-translational modification of CD49d. Finally, we showed that therapeutic agents that induce CLL mobilization from their protective niches, such as ibrutinib, modulate sialic acid levels. We propose that sialylation is an important regulator of CLL trafficking and may represent a novel target to further improve CLL therapy.