scholarly journals Harnessing lymphoma epigenetics to improve therapies

Blood ◽  
2020 ◽  
Vol 136 (21) ◽  
pp. 2386-2391
Author(s):  
Haopeng Yang ◽  
Michael R. Green
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Genetic Alterations ◽  
Cell Development ◽  
B Cell Development ◽  
Affinity Maturation

Abstract Affinity maturation and terminal differentiation of B cells via the germinal center reaction is a complex multistep process controlled by transcription factors that induce or suppress large dynamic transcriptional programs. This occurs via the recruitment of coactivator or corepressor complexes that epigenetically regulate gene expression by post-translationally modifying histones and/or remodeling chromatin structure. B-cell–intrinsic developmental programs both regulate and respond to interactions with other cells in the germinal center that provide survival and differentiation signals, such as T-follicular helper cells and follicular dendritic cells. Epigenetic and transcriptional programs that naturally occur during B-cell development are hijacked in B-cell lymphoma by genetic alterations that directly or indirectly change the function of transcription factors and/or chromatin-modifying genes. These in turn skew differentiation toward the tumor cell of origin and alter interactions between lymphoma B cells and other cells within the microenvironment. Understanding the mechanisms by which genetic alterations perturb epigenetic and transcriptional programs regulating B-cell development and immune interactions may identify opportunities to target these programs using epigenetic-modifying agents. Here, we discuss recently published studies centered on follicular lymphoma and diffuse large B-cell lymphoma within the context of prior knowledge, and we highlight how these insights have informed potential avenues for rational therapeutic interventions.

scholarly journals Harnessing lymphoma epigenetics to improve therapies (article not eligible for CME credit)

Hematology ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 95-100
Author(s):  
Haopeng Yang ◽  
Michael R. Green
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Genetic Alterations ◽  
Cell Development ◽  
B Cell Development ◽  
Affinity Maturation

Abstract Affinity maturation and terminal differentiation of B cells via the germinal center reaction is a complex multistep process controlled by transcription factors that induce or suppress large dynamic transcriptional programs. This occurs via the recruitment of coactivator or corepressor complexes that epigenetically regulate gene expression by post-translationally modifying histones and/or remodeling chromatin structure. B-cell–intrinsic developmental programs both regulate and respond to interactions with other cells in the germinal center that provide survival and differentiation signals, such as T-follicular helper cells and follicular dendritic cells. Epigenetic and transcriptional programs that naturally occur during B-cell development are hijacked in B-cell lymphoma by genetic alterations that directly or indirectly change the function of transcription factors and/or chromatin-modifying genes. These in turn skew differentiation toward the tumor cell of origin and alter interactions between lymphoma B cells and other cells within the microenvironment. Understanding the mechanisms by which genetic alterations perturb epigenetic and transcriptional programs regulating B-cell development and immune interactions may identify opportunities to target these programs using epigenetic-modifying agents. Here, we discuss recently published studies centered on follicular lymphoma and diffuse large B-cell lymphoma within the context of prior knowledge, and we highlight how these insights have informed potential avenues for rational therapeutic interventions.

scholarly journals Transcription factors IRF8 and PU.1 are required for follicular B cell development and BCL6-driven germinal center responses

2019 ◽  
Vol 116 (19) ◽  
pp. 9511-9520 ◽  
Author(s):  
Hongsheng Wang ◽  
Shweta Jain ◽  
Peng Li ◽  
Jian-Xin Lin ◽  
Jangsuk Oh ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Critical Role ◽  
B Cell Lymphoma ◽  
Cell Development ◽  
Affinity Maturation

The IRF and Ets families of transcription factors regulate the expression of a range of genes involved in immune cell development and function. However, the understanding of the molecular mechanisms of each family member has been limited due to their redundancy and broad effects on multiple lineages of cells. Here, we report that double deletion of floxed Irf8 and Spi1 (encoding PU.1) by Mb1-Cre (designated DKO mice) in the B cell lineage resulted in severe defects in the development of follicular and germinal center (GC) B cells. Class-switch recombination and antibody affinity maturation were also compromised in DKO mice. RNA-seq (sequencing) and ChIP-seq analyses revealed distinct IRF8 and PU.1 target genes in follicular and activated B cells. DKO B cells had diminished expression of target genes vital for maintaining follicular B cell identity and GC development. Moreover, our findings reveal that expression of B-cell lymphoma protein 6 (BCL6), which is critical for development of germinal center B cells, is dependent on IRF8 and PU.1 in vivo, providing a mechanism for the critical role for IRF8 and PU.1 in the development of GC B cells.

scholarly journals Transcription factors of the alternative NF-κB pathway are required for germinal center B-cell development

2016 ◽  
Vol 113 (32) ◽  
pp. 9063-9068 ◽  
Author(s):  
Nilushi S. De Silva ◽  
Michael M. Anderson ◽  
Amanda Carette ◽  
Kathryn Silva ◽  
Nicole Heise ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Alternative Pathway ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Surface Receptor ◽  
Signaling Cascade

The NF-κB signaling cascade relays external signals essential for B-cell growth and survival. This cascade is frequently hijacked by cancers that arise from the malignant transformation of germinal center (GC) B cells, underscoring the importance of deciphering the function of NF-κB in these cells. The NF-κB signaling cascade is comprised of two branches, the canonical and alternative NF-κB pathways, mediated by distinct transcription factors. The expression and function of the transcription factors of the alternative pathway, RELB and NF-κB2, in late B-cell development is incompletely understood. Using conditional deletion of relb and nfkb2 in GC B cells, we here report that ablation of both RELB and NF-κB2, but not of the single transcription factors, resulted in the collapse of established GCs. RELB/NF-κB2 deficiency in GC B cells was associated with impaired cell-cycle entry and reduced expression of the cell-surface receptor inducible T-cell costimulator ligand that promotes optimal interactions between B and T cells. Analysis of human tonsillar tissue revealed that plasma cells and their precursors in the GC expressed high levels of NF-κB2 relative to surrounding lymphocytes. Accordingly, deletion of nfkb2 in murine GC B cells resulted in a dramatic reduction of antigen-specific antibody-secreting cells, whereas deletion of relb had no effect. These results demonstrate that the transcription factors of the alternative NF-κB pathway control distinct stages of late B-cell development, which may have implications for B-cell malignancies that aberrantly activate this pathway.

Constitutively Activated STAT3 Promotes Cell Proliferation and Survival in the Activated B Cell Subtype of Diffuse Large B Cell Lymphomas.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1621-1621
Author(s):  
Bihui Hilda Ye ◽  
Beibei Belinda Ding ◽  
Jian Jessica Yu ◽  
Raymond Y.-L. Yu ◽  
Lourdes M. Mendez ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
B Cell Lymphoma ◽  
Cell Development ◽  
B Cell Development ◽  
Reciprocal Relationship ◽  
B Cell Lymphomas ◽  
Large B Cell

Abstract During B cell development, cell proliferation and survival are regulated by stage-specific transcription factors. Accordingly, distinct oncogenic pathways are employed by B cell lymphomas representing different stages of B cell development. Diffuse large B cell lymphoma (DLBCL) contains at least two main phenotypic subtypes, i.e. the germinal center B cell-like (GCB-DLBCL) and the activated B cell-like (ABC-DLBCL) groups. It has been shown that GCB-DLBCL responds favorably to chemotherapy and expresses high levels of BCL6, a transcription repressor known to play a causative role in lymphomagenesis. In comparison, ABC-DLBCL has lower levels of BCL6, constitutively activated NF-kappaB and tends to be refractory to chemotherapy. In this study, we investigated the relationship between BCL6 and STAT3 expression/activation in DLBCL and normal GC B cells. Our results demonstrate that BCL6 directly inhibits transcription of the STAT3 gene by binding to two BCL6 sites in its 5′ regulatory region. As a result, high level STAT3 expression and activation are preferentially detected in ABC-DLBCL and BCL6-negative normal germinal center B cells. Specifically, in tonsillar GCs, STAT3 expression and activation is restricted to a previously uncharacterized subset of BCL6−Blimp-1− B cells in the apical light zone. The location and phenotype of these cells suggest that they are in the process of exiting the BCL6-directed GC program and transitioning to a plasma cell differentiation process governed by Blimp-1. The reciprocal relationship between BCL6 and STAT3 is also conserved in DLBCL such that STAT3 expression and activation is preferentially associated with the BCL6-low, ABC subtype. Most importantly, inactivating STAT3 by either AG490 or small interference RNA in ABC-DLBCL cells inhibits cell proliferation and triggers apoptosis. These phenotypes are accompanied by decreased expression of several known STAT3 target genes, including c-Myc, JunB and Mcl-1, and increased expression of the cell cycle inhibitor p27. In addition to identifying STAT3 as a novel BCL6 target gene, our results define STAT3 activation as a second oncogenic pathway operating in ABC-DLBCL and suggest that blocking STAT3 may be potentially therapeutic in treatment of these aggressive lymphomas.

scholarly journals Normal and Aberrant NKL-Code in B-Cell Development and Lymphoma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3901-3901
Author(s):  
Stefan Nagel ◽  
MacLeod A.F. Roderick ◽  
Corinna Meyer ◽  
Maren Kaufmann ◽  
Hans G. Drexler
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
Homeobox Genes ◽  
Homeobox Gene ◽  
B Cell Lymphoma ◽  
Cell Development ◽  
B Cell Development

Abstract Homeobox genes encode transcription factors which regulate basic processes in development and cell differentiation. Several members of the NKL subclass are deregulated in T-cell progenitors and support leukemogenesis. We have recently described particular expression patterns of nine NKL homeobox genes in early hematopoiesis and T-cell development. Here, we screened NKL homeobox gene activities in normal B-cell development and extended the NKL-code to include this lymphoid lineage. Analysis of public expression profiling datasets revealed that HHEX and NKX6-3 were the only members differentially active in naïve B-cells, germinal center B-cells, plasma cells and memory B-cells. Subsequent examination of different types of B-cell malignancies showed both aberrant overexpression of NKL-code members and ectopic activation of subclass members physiologically silent in lymphopoiesis including BARX2, DLX1, EMX2, NKX2-1, NKX2-2 and NKX3-2. Based on these findings we performed detailed studies of the B-cell specific NKL homeobox gene NKX6-3 which showed enhanced activity in patient subsets of follicular lymphoma, mantle cell lymphoma and diffuse large B-cell lymphoma (DLBCL), and in three DLBCL cell lines to serve as in vitro models. While excluding genomic and chromosomal rearrangements at the locus of NKX6-3 (8p11) promoter studies demonstrated that B-cell factors MYB and PAX5 activated NKX6-3 transcription. Furthermore, aberrant BMP7/SMAD1-signalling and deregulated expression of chromatin complex components AUTS2 and PCGF5 promoted NKX6-3 activation. Finally, NKL homeobox genes HHEX, HLX, MSX1 and NKX6-3 were expressed in B-cell progenitors and generated a regulatory gene network in cell lines which we propose may provide physiological support for NKL-code formation in early B-cell development. Together, we identified an NKL-code in B-cell development whose violation may deregulate differentiation and promote malignant transformation. Disclosures No relevant conflicts of interest to declare.

Regulation of Transcription Factors Foxp1, E2A and Egr-1 By microRNA-191 Constrains B Lymphocyte Development and Suppresses Development of Diffuse Large B Cell Lymphoma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 287-287
Author(s):  
Marcin Lyszkiewicz ◽  
Jonas Blume ◽  
Natalia Zietara ◽  
Katrin Witzlau ◽  
Jacek Puchalka ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cell ◽  
Cell Lymphoma ◽  
Ectopic Expression ◽  
B Cell Lymphoma ◽  
Cell Development ◽  
B Cell Development ◽  
Large B Cell Lymphoma ◽  
B Lineage ◽  
Large B Cell

Abstract Development of B-cells in the bone marrow is a tightly controlled, multi-step process. Whereas its major transcriptional regulators are well characterized, less is known about its post-transcriptional regulation. It has been demonstrated that B cell development critically depends on microRNAs. Yet, the role of individual members still remains to be uncovered. Relatively subtle regulatory effects of miRNAs are well-visible in the pathways which require tight control. Disruption of such a pathway, where the protein function (i.e. transcription factor) highly depends on the gene dosage, is major cause of malignant transformation. We identified transcription factors Foxp1, E2A and Egr1 as direct targets of microRNA miR-191. Reduced expression of these transcription factors through ectopic expression of miR-191 in B-cell progenitors resulted in numerous secondary effects, such as downregulation of Rag1, Rag2, Dntt and Il7r alpha genes. In consequence, we observed impaired immunoglobulin heavy chain rearrangement and limited responsiveness to IL-7 of B cell progenitors resulting in partial developmental arrest and predisposition of immature B-cells to death during negative selection. Finally, we showed that co-overexpression of E2A or FoxP1 and miR-191 restored normal B cell development, supporting the hypothesis that both transcription factors are functionally relevant targets of miR-191. Having established a regulatory cascade comprising miR-191 at the top of hierarchy and the transcription factors Foxp1, E2A and Egr1 as its direct targets we sought to identify a pathophysiological scenario in which this cascade might be explored therapeutically. Given that the most aggressive forms of human diffuse large B cell lymphoma (DLBCL) are FOXP1 dependent, we assessed whether miR-191 was able to limit growth of DLBCL. Of note, in vivo ectopic expression of miR-191 prevented the growth of DLBCL. Consistent with murine data, expression of the three target genes FOXP1, EGR1 and TCF3 (encoding E2A) was decreased upon miR-191 overexpression. Interestingly, treatment with the histone deacetylase inhibitor vorinostat revealed decreased resistance to cell death of DLBCL lines overexpressing miR-191 in vitro. Thus, our data describe a new regulatory pathway, where miR-191 by fine-tuning key B-lineage transcription factors acts as modulator of B-cell development as well as tumor suppressor in B-lineage malignancy. Disclosures No relevant conflicts of interest to declare.

scholarly journals Conditional antibody expression to avoid central B cell deletion in humanized HIV-1 vaccine mouse models

2020 ◽  
Vol 117 (14) ◽  
pp. 7929-7940
Author(s):  
Ming Tian ◽  
Kelly McGovern ◽  
Hwei-Ling Cheng ◽  
Peyton Waddicor ◽  
Lisa Rieble ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Mouse Models ◽  
Negative Selection ◽  
Cell Development ◽  
B Cell Development ◽  
Affinity Maturation ◽  
Variable Regions ◽  
Conditional Expression ◽  
Hiv 1

HIV-1 vaccine development aims to elicit broadly neutralizing antibodies (bnAbs) against diverse viral strains. In some HIV-1–infected individuals, bnAbs evolved from precursor antibodies through affinity maturation. To induce bnAbs, a vaccine must mediate a similar antibody maturation process. One way to test a vaccine is to immunize mouse models that express human bnAb precursors and assess whether the vaccine can convert precursor antibodies into bnAbs. A major problem with such mouse models is that bnAb expression often hinders B cell development. Such developmental blocks may be attributed to the unusual properties of bnAb variable regions, such as poly-reactivity and long antigen-binding loops, which are usually under negative selection during primary B cell development. To address this problem, we devised a method to circumvent such B cell developmental blocks by expressing bnAbs conditionally in mature B cells. We validated this method by expressing the unmutated common ancestor (UCA) of the human VRC26 bnAb in transgenic mice. Constitutive expression of the VRC26UCA led to developmental arrest of B cell progenitors in bone marrow; poly-reactivity of the VRC26UCA and poor pairing of the VRC26UCA heavy chain with the mouse surrogate light chain may contribute to this phenotype. The conditional expression strategy bypassed the impediment to VRC26UCA B cell development, enabling the expression of VRC26UCA in mature B cells. This approach should be generally applicable for expressing other bnAbs that are under negative selection during B cell development.

The Loss of Kdm6a in B-Cell Development Causes Germinal Center Hyperplasia and Impedes the B-Cell Immune Response in a Specific Manner

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 5-5
Author(s):  
Ling Tian ◽  
Monique Chavez ◽  
Lukas D Wartman
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Cell Development ◽  
Young Female ◽  
B Cell Development ◽  
Cell Immune Response ◽  
Germinal Center Hyperplasia

Putative loss-of-function mutations in KDM6A, an X-linked H3K27 demethylase, occur recurrently in B-cell malignancies, including B-cell non-Hodgkin lymphoma. How the KDM6A in normal B cell development and function, as well as the mechanism(s) by which its loss contributes lymphomagenesis has not been defined. To address this issue, we generated a conditional knockout mouse of the Kdm6a gene (with LoxP sites flanking the 3rd exon) and crossed these mice with Vav1-Cre transgenic mice to selectively inactivate Kdm6a in hematopoietic stem/progenitor cells. Our previous data have shown young Kdm6a-null mice have a myeloid skewing in the bone marrow, spleen and peripheral blood. These changes became more pronounced with age and were specific to the female, homozygous Kdm6a knockout mice. Early B-cell development is also altered in female Kdm6a-null mice. Flow cytometry showed a decrease in multipotent progenitor cells (MPPs) with a decrease in both common lymphoid progenitors (CLPs) and B cell-biased lymphoid progenitors (BLPs) in young, female Kdm6a-null mice bone marrow. B-cell progenitor analysis (Hardy profiles) showed an increase in Fraction A with a concomitant decrease in Fraction B/C and Fraction D. The GC B-cells are thought to be the cell-of-origin of diffuse large B-cell lymphoma (DLBCL). To determine if the loss of Kmd6a could impact the mature B cells undergo germinal center (GC) reaction, we immunized the young, female Kdm6a-null mcie and wildtype littermates with T cell-dependent antigen sheep red blood cell (SRBC). Mice were scrificed 14 days after immunization, spleen cells were examined by flow cytometry. As expected, we observed a significant increase in the percentage of GC B cells (B220+GL7+CD95+) from female Kdm6a-null mice compared to control mice. We also observed differences in the percentage of other B-cell subsets between these mice, including an increase in plasma cells (B220-CD138+) and memory B cells (B220+CD19+CD27+), concomitant with an increase trend towards the elevated marginal zone B cells (B220+CD23loCD21+) and transitional B cells (B220+CD23-CD21-). In contrast, there was a decrease in the follicular zone B cells (B220+CD23-CD21-) and plasmablast (B220+CD138+). To analyze the levels of SRBC-specific Abs from immunized mice, serum was collected from blood at day 14. A flow cytometry-based assay was performed to detect the fluorescent-labeled SRBC-specfic Abs for immunoglobulin. Results showed that the abundance of non-class-switched anti-SRBC IgM level was significantly increased in female Kdm6a-null mice serum compared with control mice. In contrast, these mice had significantly decreased anti-SRBC IgA, IgG, IgG1, IgG3 and IgE levels indicating a isotype class switch defect. The aberrant GC phenotype induced by SRBC indeicated that kdm6a loss results in expansion of GC B cells, which subsequently enhances the plasma cell generation. This finding prompted us to investigate if the Kdm6a impairs the immunoglobulin affinity maturation. Therefore, we analyzed the ability of female Kdm6a-null mice and wildtype littermates to generate specific Abs against another T cell-dependent antigen NP-Chicken Gamma Globulin (NP-CGG). Mice were immunized with NP-CGG (29) and serum were collected weekly up to 8 weeks total. ELISA analysis of serum revealed that NP-specfic total Ig level were similar for both groups of mice over time. However, consistent with the SRBC immunization results, we did observed a sinificant reduction in the titers of NP-specific IgA and IgG1 Abs in female Kdm6a-null mice compared with control mice at each time point, while these mice had a sinificant increase in NP-specific IgM Abs, which indicating the loss of Kdm6a disrupts the balance between non-class-switched and class-switched NP-specific Abs isotypes (Figure 1A-D). Likewise, we also observed an increase in the percentage of GC B cells and plasma cells 8 weeks after NP-CGG immunization by flow cytometry. Again, our findings indicate the loss of Kdm6a causes germinal center hyperplasia, enhances plasma cell differentiation, and likely impairs class switch recombination (CSR). Taken together, our data shows that Kdm6a plays an important, but complex, role in B-cell transiting in the GC reaction and that loss of Kdm6a causes germinal center hyperplasia and impedes the B-cell immune response in a specific manner that may contribute to infection and B-cell malignancies. Disclosures Wartman: Novartis: Consultancy; Incyte: Consultancy.

A Germinal Center- Derived B Cell Lymphoma Model

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2008-2008
Author(s):  
Ryan T Phan ◽  
Khang Nguyen ◽  
Sonia Romero ◽  
Alice Nicolson ◽  
Phillipp Nham ◽  
...  
Keyword(s):  
B Cells ◽  
Mouse Model ◽  
B Cell ◽  
Germinal Center ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Chromosomal Translocations ◽  
Dna Breaks ◽  
Dna Rearrangements ◽  
Human B Cell

Abstract Abstract 2008 Most human B-cell lymphomas represent mature phenotypes of germinal center (GC) or post-GC origin and are frequently associated with chromosomal translocations, often involving the rearrangement of immunoglobulin (Ig) loci to various cellular oncogenes, leading to oncogenic activation. The mechanisms underlying these processes, however, are not well understood. Several studies suggest that these genetic lesions arise from errors of physiologic DNA rearrangements in GC B cells, namely class switch recombination (CSR) and somatic hypermutation (SHM). Here we report the generation of a mouse model in which DNA breaks are physiologically instituted in mature B cells, yet inefficiently repaired via specific deletion of DNA repair gene XRCC4 in GC B cells, thus effectively creating an in vivo environment for errors in DNA rearrangements. These activated B cells exhibit significant increased chromosomal IgH locus breaks and reduced CSR. In p53-deficient background, these mice develop B-cell lymphoma from 5.5 to 16 months. These clonally developed tumors characteristically harbor chromosomal translocations and phenotypically resemble mature phenotypes. Many of these tumors bear mutated V genes, suggesting that those cells have transited through GC. Thus, this mouse model mimics human B-cell lymphoma and might be useful for the development of therapeutic interventions in B-cell lymphoma. Disclosures: No relevant conflicts of interest to declare.

Preferential Acquision of N-Glycosylation Sites in the VDJ Region in Germinal Center B-Cell-Like Difusse Large B-Cell Lymphoma

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1589-1589 ◽  
Author(s):  
Miguel Alcoceba ◽  
Elena Sebastián ◽  
Ana Balanzategui ◽  
Luis Marín ◽  
Santiago Montes-Moreno ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Marginal Zone ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Marginal Zone Lymphoma ◽  
Large B Cell Lymphoma ◽  
Glycosylation Sites ◽  
Large B Cell

Abstract Abstract 1589 Introduction: Acquired potentially N-glycosylation sites are produced by somatic hypermutation (SHM) in the immunoglobulin (Ig) variable region. This phenomenon is produced in ∼9% of normal B-cells and seems to be related to certain B-cell lymphoproliferative disorders (B-LPDs) such as follicular lymphoma (FL, 79%), endemic Burkitt lymphoma (BL, 82%) and diffuse large B-cell lymphoma (DLBCL, 41%). These data suggest that new potential N-glycosylation sites could be related to germinal center B (GCB)-LPDs. By contrast, in other B-LPDs, such as chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), MALT lymphoma, Waldenström macroglobulinemia (WM) or multiple myeloma (MM), these modifications have not been analyzed in deep. Aims: To evaluate the acquisition of potential N-glycosylation sites in B-LPDs, including immunohystochemical DLBCL subtypes (GCB and non-GCB) and specific non-GCB-LPDs, such as hairy cell leukemia (HCL), splenic marginal-zone lymphoma (SMZL), CLL, MCL, ocular extranodal marginal zone lymphoma (OAEMZL), MM and WM. Patients: A total of 953 sequences (203 from our group and 750 previously published sequences) of B-LPDs were included. Diagnosis distribution was as follows: DLBCL (n=235), MCL (n=235), CLL (n=166), MM (n=96), OAEMZL (n=82), SMZL (n=68), WM (n=38) and HCL (n=33). Methods: Acquired N-glycosylation sites were counted according to the sequence Asn-X-Ser/Thr, where X could be any amino acid except Pro. Natural motifs in germline sequences of IGHV1–08, IGHV4–34 e IGHV-5a were not considered. Fisher test was used to perform comparisons between groups. To distinguish DLBCL biological subtypes (GCB and non-GCB DLBCL), Hans' algorithm was used. Results: A total of 83 out of the 235 DLBCL cases acquired at least a new N-glycosylation site, a higher value than in normal B-cells (35% vs. 9%, p<0.0001). Higher incidence of these motifs in the group of GCB as compared to non-GCB DLBCL were observed (52% vs. 20%, p<0.0001). Those cases diagnosed of HCL, CLL, MCL, MM, WM, OAEMZL and SMZL presented a reduced number of new N-glycosylation sites, showing similar values than normal B-cells (range 3–18%, p=ns). Conclusions: We described for the first time the pattern of N-glycosylation in HCL, SMZL, OAEMZL and in the immunohystochemical DLBCL subtypes, where the GCB-DLBCL showed a higher number of new N-glycosylation sites with respect to non-GCB DLBCL and other non-GCB-LPDs. The presence of novel N-glycosylation sites in FL, BL and in GCB-DLBCL strongly suggests that these motifs are characteristic of the germinal center B-LPDs. Disclosures: No relevant conflicts of interest to declare.

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