Nonstochastic pairing of immunoglobulin heavy and light chains expressed by chronic lymphocytic leukemia B cells is predicated on the heavy chain CDR3

Peripheral B cells from patients with hepatitis C virus-associated lymphoma exhibit clonal expansion and an anergic-like transcriptional profile

Chronic HCV infection remains a global health concern due to its involvement in hepatic and extrahepatic diseases, including B cell non-Hodgkin lymphoma (BNHL). Clinical and epidemiological evidence support a causal role for HCV in BNHL development, although mechanistic insight is lacking. We performed RNA-sequencing on peripheral B cells from patients with HCV alone, BNHL alone, and HCV-associated BNHL to identify unique and shared transcriptional profiles associated with transformation. In patients with HCV-associated BNHL, we observed the enrichment of an anergic-like gene signature and evidence of clonal expansion that was correlated with the expression of epigenetic regulatory genes. Our data support a role for viral-mediated clonal expansion of anergic-like B cells in HCV-associated BNHL development and suggest epigenetic dysregulation as a potential mechanism driving expansion. We propose epigenetic mechanisms may be involved in both HCV-associated lymphoma and regulation of B cell anergy, representing an attractive target for clinical interventions.

Characterizing Features of Human Circulating B Cells Carrying CLL-Like Stereotyped Immunoglobulin Rearrangements

Chronic Lymphocytic Leukemia (CLL) is characterized by the accumulation of monoclonal CD5⁺ B cells with low surface immunoglobulins (IG). About 40% of CLL clones utilize quasi-identical B cell receptors, defined as stereotyped BCR. CLL-like stereotyped-IG rearrangements are present in normal B cells as a part of the public IG repertoire. In this study, we collected details on the representation and features of CLL-like stereotyped-IG in the IGH repertoire of B-cell subpopulations purified from the peripheral blood of nine healthy donors. The B-cell subpopulations were also fractioned according to the expression of surface CD5 molecules and IG light chain, IGκ and IGλ. IG rearrangements, obtained by high throughput sequencing, were scanned for the presence of CLL-like stereotyped-IG. CLL-like stereotyped-IG did not accumulate preferentially in the CD5⁺ B cells, nor in specific B-cell subpopulations or the CD5⁺ cell fraction thereof, and their distribution was not restricted to a single IG light chain type. CLL-like stereotyped-IG shared with the corresponding CLL stereotype rearrangements the IGHV mutational status. Instead, for other features such as IGHV genes and frequency, CLL stereotyped-IGs presented a CLL-like subset specific behavior which could, or could not, be consistent with CLL stereotyped-IGs. Therefore, as opposed to the immuno-phenotype, the features of the CLL stereotyped-IG repertoire suggest a CLL stereotyped subset-specific ontogeny. Overall, these findings suggest that the immune-genotype can provide essential details in tracking and defining the CLL cell of origin.

Matrix-assisted laser desorption ionization mass spectrometry profiling of plasma exosomes evaluates osteosarcoma metastasis

Osteosarcoma is the most common primary sarcoma of bone among adolescents, often characterized by early lung metastasis resulting in high mortality. Recently, exosomes have been used in liquid biopsy to monitor tumors. Herein, we used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to profile human plasma exosomes for the evaluation of osteosarcoma lung metastasis. Forty patients with osteosarcoma with (n = 20) or without (n = 20) lung metastasis as well as 12 heathy controls were recruited. Exosomes were isolated from human plasma for MALDI-TOF MS analysis. Multivariate statistical analyses were performed based on the MALDI-TOF mass spectra. The strategy can efficiently differentiate osteosarcomas from healthy controls and further discriminate osteosarcoma lung metastasis from non-lung metastasis. We identified seven exosomal proteins as potential biomarkers of osteosarcoma lung metastasis. The proposed method holds great promise to clinically diagnose osteosarcoma and monitor osteosarcoma lung metastasis.

Clonal immunoglobulin λ light-chain gene rearrangements detected by next generation sequencing in POEMS syndrome

Polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome is a rare plasma cell dyscrasia characterized by polyneuropathy, organomegaly, endocrinopathy, extravascular fluid overload, M protein, and a myriad of skin changes. The pathogenesis is poorly understood, but monoclonal plasma cells are λ-restricted and these immunoglobulin λ light chain variable (IGLV) region genes are derived from only two germlines, either IGLV1-44 or 1-40. Here we analyzed the clonal IGLV gene rearrangements of genomic DNA samples of bone marrow mononuclear cells using next-generation sequencing (NGS) to understand the clonal composition of IGLV genes in patients with POEMS syndrome (n = 30). The dominant IGLV gene rearrangement of POEMS syndrome-specific germline sequences were significantly increased in 11 POEMS patients (36.7%; IGLV1-44: n = 9, IGLV1-40: n = 2). In some cases, IGLV gene rearrangement clone was not detected as significant increase but was detected using cDNA samples by heteroduplex (HD) analysis and Sanger sequencing, suggesting that the quite small number of monoclonal plasma cells may produce large quantity of mRNA of monoclonal proteins. However, significant increase of dominant clone sizes was not directly linked to the initial disease status. On the other hand, in cases with significantly increased dominant clones, they decreased and increased accompanying with disease remission and relapse. These data demonstrate that monoclonal plasma cells are related to the pathogenesis of POEMS syndrome.

Secretory IgM Exacerbates Tumor Progression by Inducing Accumulations of MDSCs in Mice

Chronic lymphocytic leukemia (CLL) cells can secrete immunoglobulin M. However, it is not clear whether secretory IgM (sIgM) plays a role in disease progression. We crossed the Eμ-TCL1 mouse model of CLL, in which the expression of human TCL1 oncogene was driven by the V(H) promoter-Ig(H)-Eμ enhancer, with MD4 mice whose B cells produced B-cell receptor (membrane-bound IgM) and sIgM with specificity for hen egg lysozyme (HEL). CLL cells that developed in these MD4/Eμ-TCL1 mice reactivated a parental Ig gene allele and secreted IgM, and did not recognize HEL. The MD4/Eμ-TCL1 mice had reduced survival, increased myeloid-derived suppressor cells (MDSC), and decreased numbers of T cells. We tested whether sIgM could contribute to the accumulation of MDSCs by crossing μS^-/- mice, which could not produce sIgM, with Eμ-TCL1 mice. The μS^-/-/Eμ-TCL1 mice survived longer than Eμ-TCL1 mice and developed decreased numbers of MDSCs which were less able to suppress proliferation of T cells. We targeted the synthesis of sIgM by deleting the function of XBP-1s and showed that targeting XBP-1s genetically or pharmacologically could lead to decreased sIgM, accompanied by decreased numbers and reduced functions of MDSCs in MD4/Eμ-TCL1 mice. Additionally, MDSCs from μS^-/- mice grafted with Lewis lung carcinoma were inefficient suppressors of T cells, resulting in slower tumor growth. These results demonstrate that sIgM produced by B cells can upregulate the functions of MDSCs in tumor-bearing mice to aggravate cancer progression. In a mouse model of CLL, production of secretory IgM led to more MDSCs, fewer T cells, and shorter survival times for the mice. Thus, secretory IgM may aggravate the progression of this cancer. Cancer Immunol Res; 6(6); 696-710. ©2018 AACR.

Altered N-Linked Glycosylation in Follicular Lymphoma and Chronic Lymphocytic Leukemia: Involvement in Pathogenesis and Potential Therapeutic Targeting

B-cell antigen receptor (BCR) expression is indispensable for survival of most B-cell malignancies. In follicular lymphoma (FL), N-linked glycosylation sites are introduced in the immunoglobulin (Ig) variable region genes. Oligosaccharides added to the acquired sites are unusually of the high-mannose type. These glycans interact with mannose-specific lectins, especially with dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN). Lectin binding to FL triggers persistent activating signals, suggesting that lectins within the tumor microenvironment promote cell survival and proliferation. Insertion of N-glycosylation sites in Ig variable region genes has been detected in other germinal center-associated lymphomas, specifically in subsets of diffuse large B-cell lymphomas and Burkitt’s lymphomas, suggesting involvement of altered glycans in pathogenesis of these malignancies as well. Furthermore, the BCR in chronic lymphocytic leukemia (CLL) carries high-mannose oligosaccharides, albeit in the heavy chain constant rather than variable region. The high expression level of the unique glycoform, particularly in the more aggressive unmutated CLL subset, suggests a functional significance for this glycan in CLL. As lectin interaction with the BCR is critical for FL and probably for some other lymphomas, targeting this interaction is considered to be an interesting therapeutic strategy. Reagents for blockade of lectin–BCR interaction may include antibodies against high-mannose glycans and mannose-based oligosaccharide mimics or non-carbohydrate glycomimetics. Moreover, as this interaction triggers signaling pathways similar to those demonstrated for BCR engagement by antigen, BCR signal transduction inhibitors may emerge as effective therapeutics for lectin-driven malignancies.

Host virus and pneumococcus-specific immune responses in high-count monoclonal B-cell lymphocytosis and chronic lymphocytic leukemia: implications for disease progression

Patients diagnosed with chronic lymphocytic leukemia (CLL) display a high incidence of infections due to an associated immunodeficiency that includes hypogammaglobulinemia. A higher risk of infections has also been recently reported for high-count monoclonal B-cell lymphocytosis, while no information is available in low-count monoclonal B-cell lymphocytosis. Here, we evaluated the status of the humoral immune system in patients with chronic lymphocytic leukemia (n=58), as well as in low- (n=71) and high- (n=29) count monoclonal B-cell lymphocytosis versus healthy donors (n=91). Total free plasma immunoglobulin titers and specific levels of antibodies against cytomegalovirus, Epstein-Barr virus, influenza and S.pneumoniae were measured by nephelometry and ELISA-based techniques, respectively. Overall, our results show that both CLL and high-count monoclonal B-cell lymphocytosis patients, but not low-count monoclonal B-cell lymphocytosis subjects, present with relatively high levels of antibodies specific for the latent viruses investigated, associated with progressively lower levels of S.pneumoniae-specific immunoglobulins. These findings probably reflect asymptomatic chronic reactivation of humoral immune responses against host viruses associated with expanded virus-specific antibody levels and progressively decreased protection against other micro-organisms, denoting a severe humoral immunodeficiency state not reflected by the overall plasma immunoglobulin levels. Alternatively, these results could reflect a potential role of ubiquitous viruses in the pathogenesis of the disease. Further analyses are necessary to establish the relevance of such asymptomatic humoral immune responses against host viruses in the expansion of the tumor B-cell clone and progression from monoclonal B-cell lymphocytosis to CLL.

Transitional B Cells in Early Human B Cell Development - Time to Revisit the Paradigm?

The B cell repertoire is generated in the adult bone marrow by an ordered series of gene rearrangement processes that result in massive diversity of immunoglobulin (Ig) genes and consequently an equally large number of potential specificities for antigen. As the process is essentially random, the cells exhibiting excess reactivity with self-antigens are generated and need to be removed from the repertoire before the cells are fully mature. Some of the cells are deleted, and some will undergo receptor editing to see if changing the light chain can rescue an autoreactive antibody. As a consequence, the binding properties of the B cell receptor are changed as development progresses through pre-B ≫ immature ≫ transitional ≫ naïve phenotypes. Using long-read, high-throughput, sequencing we have produced a unique set of sequences from these four cell types in human bone marrow and matched peripheral blood, and our results describe the effects of tolerance selection on the B cell repertoire at the Ig gene level. Most strong effects of selection are seen within the heavy chain repertoire and can be seen both in gene usage and in CDRH3 characteristics. Age-related changes are small, and only the size of the CDRH3 shows constant and significant change in these data. The paucity of significant changes in either kappa or lambda light chain repertoires implies that either the heavy chain has more influence over autoreactivity than light chain and/or that switching between kappa and lambda light chains, as opposed to switching within the light chain loci, may effect a more successful autoreactive rescue by receptor editing. Our results show that the transitional cell population contains cells other than those that are part of the pre-B ≫ immature ≫ transitional ≫ naïve development pathway, since the population often shows a repertoire that is outside the trajectory of gene loss/gain between pre-B and naïve stages.

Stereotyped subset #1 chronic lymphocytic leukemia: a direct link between B-cell receptor structure, function, and patients' prognosis

Chronic lymphocytic leukemia (CLL) with stereotyped B-cell receptor (BCR) belonging to subset #1 (IGHV1-5-7/ IGKV1-39) display a poor outcome. To characterize their genetic and genomic features and BCR function, we selected 20 subset #1 CLL from a series of 579 cases. Subset #1 CLL, all showing unmutated IGHV, were associated with the presence of del(11q) (50%) in comparison with unmutated CLL, unmutated stereotyped CLL other than subset #1 and with cases using the same IGHV genes but a heterogeneous VH CDR3 (non-subset #1 CLL). There were no distinctive features regarding CD38, ZAP-70, and TP53 disruption. NOTCH1, SF3B1, and BIRC3 were mutated in 15%, 0%, and 5% of cases, respectively, while BIRC3 was deleted in 22% of cases. Microarray unsupervised analysis on 80 unmutated/mutated/stereotyped/non-stereotyped CLL showed a tight clustering of subset #1 cases. Their genomic signature exhibited several differentially expressed transcripts involved in BCR signal transduction, apoptosis regulation, cell proliferation, and oxidative processes, regardless of del(11q). Accordingly, BCR ligation with anti-IgM revealed a significant higher proliferation of subset #1 versus unmutated non-subset #1 CLL, both at baseline and after 24–48 hr stimulation. Subset #1 CLL represent a paradigmatic example of the direct link between BCR structure, function, and patients prognosis.

The pathogenesis of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by the clonal expansion of CD5(+)CD23(+) B cells in blood, marrow, and second lymphoid tissues. Gene-expression profiling and phenotypic studies suggest that CLL is probably derived from CD5(+) B cells similar to those found in the blood of healthy adults. Next-generation sequencing has revealed recurrent genetic lesions that are implicated in CLL pathogenesis and/or disease progression. The biology of CLL is entwined with its microenvironment, in which accessory cells can promote leukemia cell growth and/or survival. Recently, much attention has been focused on the CLL B cell receptor (BCR) and on chemokine receptors that enable CLL cells to home to lymphoid tissues and to establish the leukemia microenvironment. Agents that can interfere with BCR signaling or chemokine-receptor signaling, or that target surface antigens selectively expressed on CLL cells, promise to have significant therapeutic benefit in patients with this disease.

The changing paradigm of chronic lymphocytic leukemia management

B cell-chronic lymphocytic leukemia (CLL), the commonest adult leukemia in western world, is today most often diagnosed at early-stage, following the accidental detection of lymphocytosis during a routine blood analysis. Moreover, the expectations of CLL patients have dramatically changed in the past decade and for the first time a significant overall survival improvement has been demonstrated in the disease--at least in the younger and fit patients--with the use of the FCR regimen, which combines rituximab fludarabine and cyclophosphamide. New drugs and new regimens are currently being developed for the relapsed patients and for those too old or too frail to receive aggressive treatments. Some of these promising compounds will likely be part of the future front-line treatments. Additionally, the increasing knowledge on the molecular features that predict the clinical outcome may soon result in a molecular classification of the disease. These acquisitions are producing a migration from palliative care to a curative and individually-tailored approach. In this review we tried to summarize the advances achieved in the past decade and help the specialists in internal medicine and the general practitioners to understand the completely changed scenario in which the disease should nowadays be managed.

IGHV1-69-encoded antibodies expressed in chronic lymphocytic leukemia react with malondialdehyde-acetaldehyde adduct, an immunodominant oxidation-specific epitope

The immunoglobulins expressed by chronic lymphocytic leukemia (CLL) B cells are highly restricted, suggesting they are selected for binding either self or foreign antigen. Of the immunoglobulin heavy-chain variable (IGHV) genes expressed in CLL, IGHV1-69 is the most common, and often is expressed with little or no somatic mutation, and restricted IGHD and IGHJ gene usage. We found that antibodies encoded by one particular IGHV1-69 subset, designated CLL69C, with the HCDR3 encoded by the IGHD3-3 gene in reading frame 2 and IGHJ6, specifically bound to oxidation-specific epitopes (OSE), which are products of enhanced lipid peroxidation and a major target of innate natural antibodies. Specifically, CLL69C bound immunodominant OSE adducts termed MAA (malondialdehyde–acetaldehyde-adducts), which are found on apoptotic cells, inflammatory tissues, and atherosclerotic lesions. It also reacted specifically with MAA-specific peptide mimotopes. Light chain shuffling indicated that non-stochastically paired L chain of IGLV3-9 contributes to the antigen binding of CLL69C. A nearly identical CLL69C Ig heavy chain was identified from an MAA-enriched umbilical cord phage displayed Fab library, and a derived Fab with the same HCDR3 rearrangement displayed identical MAA-binding properties. These data support the concept that OSE (MAA-epitopes), which are ubiquitous products of inflammation, may play a role in clonal selection and expansion of CLL B cells.

A mutated B cell chronic lymphocytic leukemia subset that recognizes and responds to fungi

B cell chronic lymphocytic leukemia (CLL), the most common leukemia in adults, is a clonal expansion of CD5(+)CD19(+) B lymphocytes. Two types of CLLs are being distinguished as carrying either unmutated or somatically mutated immunoglobulins (Igs), which are associated with unfavorable and favorable prognoses, respectively. More than 30% of CLLs can be grouped based on their expression of stereotypic B cell receptors (BCRs), strongly suggesting that distinctive antigens are involved in the development of CLL. Unmutated CLLs, carrying Ig heavy chain variable (IGHV) genes in germline configuration, express low-affinity, poly-, and self-reactive BCRs. However, the antigenic specificity of CLLs with mutated IGHV-genes (M-CLL) remained elusive. In this study, we describe a new subset of M-CLL, expressing stereotypic BCRs highly specific for β-(1,6)-glucan, a major antigenic determinant of yeasts and filamentous fungi. β-(1,6)-glucan binding depended on both the stereotypic Ig heavy and light chains, as well as on a distinct amino acid in the IGHV-CDR3. Reversion of IGHV mutations to germline configuration reduced the affinity for β-(1,6)-glucan, indicating that these BCRs are indeed affinity-selected for their cognate antigen. Moreover, CLL cells expressing these stereotypic receptors proliferate in response to β-(1,6)-glucan. This study establishes a class of common pathogens as functional ligands for a subset of somatically mutated human B cell lymphomas.

Immunoglobulin gene repertoire in chronic lymphocytic leukemia: insight into antigen selection and microenvironmental interactions

Immunogenetic analysis of the B cell receptors (BCRs) has been a richly rewarding field for unraveling the pathogenesis of human lymphomas, including CLL. A biased immunoglobulin gene repertoire is seen as evidence for selection of CLL progenitor cells by antigen. Additional corroborative evidence is provided by the differential prognosis of cases with distinct mutational status of the clonotypic BCRs. However, perhaps the strongest immunogenetic evidence for the importance of interactions with microenvironment in driving CLL development and evolution is the existence of subsets of patients with quasi-identical, stereotyped BCRs, collectively accounting for a remarkable one-third of the entire cohort. These observations have been instrumental in shaping the notion that CLL ontogeny is functionally driven and dynamic, rather than a simple stochastic process. From a clinical perspective, ample evidence indicates that immunogenetic information can be used for the biologically and clinically rational categorization of CLL, with important potential implications for basic, translational and clinical research.

Overexpression of TCL1 activates the endoplasmic reticulum stress response: a novel mechanism of leukemic progression in mice

Chronic lymphocytic leukemia (CLL) represents 30% of adult leukemia. TCL1 is expressed in ~ 90% of human CLL. Transgenic expression of TCL1 in murine B cells (Eμ-TCL1) results in mouse CLL. Here we show for the first time that the previously unexplored endoplasmic reticulum (ER) stress response is aberrantly activated in Eμ-TCL1 mouse and human CLL. This includes activation of the IRE-1/XBP-1 pathway and the transcriptionally up-regulated expression of Derlin-1, Derlin-2, BiP, GRP94, and PDI. TCL1 associates with the XBP-1 transcription factor, and causes the dysregulated expression of the transcription factors, Pax5, IRF4, and Blimp-1, and of the activation-induced cytidine deaminase. In addition, TCL1-overexpressing CLL cells manufacture a distinctly different BCR, as we detected increased expression of membrane-bound IgM and altered N-linked glycosylation of Igα and Igβ, which account for the hyperactive BCR in malignant CLL. To demonstrate that the ER stress-response pathway is a novel molecular target for the treatment of CLL, we blocked the IRE-1/XBP-1 pathway using a novel inhibitor, and observed apoptosis and significantly stalled growth of CLL cells in vitro and in mice. These studies reveal an important role of TCL1 in activating the ER stress response in support for malignant progression of CLL.

Analyses of recombinant stereotypic IGHV3-21-encoded antibodies expressed in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) cells that use IgH encoded by IGHV3-21 and that have a particular stereotypic third CDR (HCDR3), DANGMDV (motif-1), almost invariably express Ig L chains (IgL) encoded by IGLV3-21, whereas CLL that use IGHV3-21-encoded IgH with another stereotypic HCDR3, DPSFYSSSWTLFDY (motif-2), invariably express κ-IgL encoded by IGKV3-20. This nonstochastic pairing could reflect steric factors that preclude these IgH from pairing with other IgL or selection for an Ig with a particular Ag-binding activity. We generated rIg with IGHV3-21-encoded IgH with HCDR3 motif-1 or -2 and IgL encoded by IGKV3-20 or IGLV3-21. Each IgH paired equally well with matched or mismatched κ- or λ-IgL to form functional Ig, which we screened for binding to an array of different Ags. Ig with IGLV3-21-encoded λ-IgL could bind with an affinity of ∼ 2 × 10(-6) M to protein L, a cell-wall protein of Peptostreptococcus magnus, independent of the IgH, indicating that protein L is a superantigen for IGLV3-21-encoded λ-IgL. We also detected Ig binding to cofilin, a highly conserved actin-binding protein. However, cofilin binding was independent of native pairing of IgH and IgL and was not specific for Ig with IgH encoded by IGHV3-21. We conclude that steric factors or the binding activity for protein L or cofilin cannot account for the nonstochastic pairing of IgH and IgL observed for the stereotypic Ig made by CLL cells that express IGHV3-21.

B-cell receptor, clinical course and prognosis in chronic lymphocytic leukaemia: the growing saga of the IGHV3 subgroup gene usage

The immunoglobulin heavy chain variable gene (IGHV) mutational status has been recognized as an important predictor of prognosis in chronic lymphocytic leukaemia (CLL) since 1999. More recently, other features of the B-cell receptor, such as stereotypy, have been identified as capable of refining the prognostic potential of IGHV status in the clinical assessment of CLL patients. In this context, different genes belonging to the IGHV3 subgroup, the most frequently used subgroup in CLL, have been shown to denote disease subsets that either display a bad prognosis (i.e. IGHV3-21, IGHV3-23) or are associated with particularly good clinical outcomes, including a highly stable/indolent clinical course, even prone to spontaneous regression (i.e. IGHV3-72, IGHV3-30). The present review focuses on the molecular and biological features of CLL-expressing specific genes belonging to the IGHV3 subgroup that are known to mark disease subsets with completely different clinical courses, and may be possibly related to CLL pathogenesis via antigen and/or superantigen involvement.

Molecular insight into the biology and clinical course of hairy cell leukemia utilizing immunoglobulin gene analysis

The B cell receptor (BCR) is the functional distinguishing unit that defines any B cell. Immunoglobulin gene (IG) status is preserved in the neoplastic B cell clone and can provide an indicator of the maturation stage reached by the B cell prior to transformation. In hairy cell leukemia (HCL), several pieces of data from IG analysis provide clear hints regarding the cell of origin and the ongoing selective interactions of the tumor BCR with environmental stimuli. HCLs have variable levels of IG somatic mutations, and continue somatic mutations at low levels as well as IG class switching after transformation. More recent data also show the occurrence of selective events in the light chain of the BCR, suggesting a dominant role for IG status in the pathogenesis of HCL. Moreover, it has recently emerged that an unmutated status of the HCL IG can be associated with failure to respond to cladribine, genetic abnormalities indicative of poor outcome, and aggressive disease. These observations suggest that IG analysis may have biological and prognostic relevance in HCL and merits further characterization.

Persistent infections and their relationship with selected oncologic and non-tumor pathologies

Our earlier studies of hepatitis C virus (HCV) infection rates among blood donors at the Kyiv Municipal Blood Center revealed a 3.45% HCV+ prevalence in these "healthy" hosts. In the study here, we analyzed HCV (as well as cytomegalovirus [CMV]) prevalence among Chernobyl nuclear power plant (NPP) accident sufferers--cleanup workers, local residents, NPP workers, and convalescent patients--who suffered acute radiation syndrome (ARS) as a result of the 1986 accident, and individuals who had not been exposed to ionizing radiation (IR). Serological analyses of antibodies against each pathogen (via enzyme-linked immunosorbent assay [ELISA]) revealed the highest HCV (i.e., 27.2%) and CMV (85.6%) prevalence in the convalescent hosts. Though the HCV prevalence (reflecting a current/past infection) among the cleanup workers (and other groups) was lower (i.e., 11-25%), viral presence was "associated" with a higher incidence of selected somatic diseases, for example, thyroiditis, goiter, hypertension, Type 1 diabetes, chronic hepatitis/gastritis, in the cleanup workers. A similar scenario with respect to CMV was also seen, i.e., lower prevalence rates [relative to in ARS patients] and "association" between CMV status and incidence of chronic gastritis, arthritis, and bronchitis, in the cleanup workers and IR-non-exposed controls. Further, irrespective of CMV status, there was a clear delineation between incidence rate(s) of each of the pathologies and whether or not the person was/was not exposed in 1986. We also investigated, due to a high incidence of chronic lymphocytic leukemia (CLL) among Chernobyl sufferers, if there was homology between immunoglobulins (Igs) generated by these transformed cells and known antiviral and antimicrobial Igs. Polymerase chain reaction (PCR) analyses of Ig heavy-chain variable (IgHV) genes in cells from CLL patients who were/were not exposed in 1986 revealed a significant homology of some IgHV genes with Igs directed against infectious agents. However, no differences were found between the sequences from IR-exposed and IR-non-exposed CLL patients. Based on the findings here, we conclude that a past/ongoing presence of certain viral infections (i.e., CMV and/or HCV) in a host can modify (aggravate) the clinical course of certain somatic (i.e., non-tumor) diseases and promote malignancies (i.e., CLL), and that each of these outcomes could be modulated as a result of that host's past exposure to IR.

Surface IgM of CLL cells displays unusual glycans indicative of engagement of antigen in vivo

Surface IgM (sIgM) has a key influence on the clinical behavior of chronic lymphocytic leukemia (CLL). We now report that it exists in 2 forms with different N-glycosylation patterns in the mu-constant region. One glycoform is similar to normal B cells in bearing mature complex glycans common to most cell-surface glycoproteins. The other is an immature mannosylated form more characteristic of mu chains in the endoplasmic reticulum. Unmutated CLL (U-CLL) expresses a higher proportion of mannosylated surface mu chains than mutated CLL. Normal B cells express only the mature glycoform but can express the immature form after persistent engagement of sIgM, suggesting that glycan modification is a consequence of antigen exposure. CLL cells express variable proportions of the mannosylated form and can revert to the mature form after incubation in vitro. Both glycoforms are able to signal after sIgM engagement in vitro, leading to enhanced tyrosine phosphorylation. These findings support the concept that CLL cells are continuously exposed to antigen in vivo, driving the N-glycosylation pattern of expressed sIgM toward a mannosylated form, especially in U-CLL. Strikingly, this is reminiscent of follicular lymphoma, where mannosylated Ig is expressed constitutively via N-glycosylation sites in the variable region, suggesting a functional asset for this glycoform.

Expression of mutated IGHV3-23 genes in chronic lymphocytic leukemia identifies a disease subset with peculiar clinical and biological features

PURPOSE

B-cell chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease whose outcome can be foreseen by investigating the mutational status of immunoglobulin heavy chain variable (IGHV) genes. Moreover, a different prognosis was reported for CLL expressing specific IGHV genes in the context or not of stereotyped B-cell receptors. Here we investigated novel associations between usage of specific IGHV genes and clinical features in CLL.

EXPERIMENTAL DESIGN

Among 1,426 CLL-specific IG-rearrangements, stereotyped B-cell receptor clusters never utilized the IGHV3-23 gene. Given this notion, this study was aimed at characterizing the IGHV3-23 gene in CLL, and identifying the properties of IGHV3-23-expressing CLL.

RESULTS

IGHV3-23 was the second most frequently used (134 of 1,426) and usually mutated (M; 109 of 134) IGHV gene in our CLL series. In the vast majority of M IGHV3-23 sequences, the configuration of the 13 amino acids involved in superantigen recognition was consistent with superantigen binding. Clinically, M IGHV3-23 CLL had shorter time-to-treatment than other M non-IGHV3-23 CLL, and multivariate analyses selected IGHV3-23 gene usage, Rai staging, and chromosomal abnormalities as independent prognosticators for M CLL. Compared with M non-IGHV3-23 CLL, the gene expression profile of M IGHV3-23 CLL was deprived in genes, including the growth/tumor suppressor genes PDCD4, TIA1, and RASSF5, whose downregulation is under control of miR-15a and miR-16-1. Accordingly, relatively higher levels of miR-15a and miR-16-1 were found in M IGHV3-23 compared with M non-IGHV3-23 CLL.

CONCLUSIONS

Altogether, expression of the IGHV3-23 gene characterizes a CLL subset with distinct clinical and biological features.

From pathogenesis to treatment of chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) has several unique features that distinguish it from other cancers. Most CLL tumour cells are inert and arrested in G0/G1 of the cell cycle and there is only a small proliferative compartment; however, the progressive accumulation of malignant cells will ultimately lead to symptomatic disease. Pathogenic mechanisms have been elucidated that involve multiple external (for example, microenvironmental stimuli and antigenic drive) and internal (genetic and epigenetic) events that are crucial in the transformation, progression and evolution of CLL. Our growing understanding of CLL biology is allowing the translation of targets and biological classifiers into clinical practice.

The normal IGHV1-69-derived B-cell repertoire contains stereotypic patterns characteristic of unmutated CLL

The cell of origin of chronic lymphocytic leukemia (CLL) has long been sought, and immunoglobulin gene analysis provides new clues. In the unmutated subset (U-CLL), there is increased usage of the 51p1-related alleles of the immunoglobulin heavy chain variable 1-69 gene, often combined with selected genes and with immunoglobulin heavy chain diversity IGHJ6. Stereotypic characteristics of the HCDR3 result and suggest antigen selection of the leukemic clones. We have now analyzed 51p1/IGHJ6 combinations in normal blood B cells from 3 healthy persons for parallel sequence patterns. A high proportion (33.3% of sequences) revealed stereotypic patterns, with several (15.0%) being similar to those described in U-CLL. Previously unreported CLL-associated stereotypes were detected in 4.8%. Stereotypes (13.6%) not detected in CLL also were found. The HCDR2-IGHJ6 sequences were essentially unmutated. Junctional amino acids in normal B cells were heterogeneous, as in cases of stereotyped CLL. Phenotypically, normal B cells expressing 51p1-derived immunoglobulin M were naive. This snapshot of the naive B-cell repertoire reveals subsets of B cells closely related to those characteristic of CLL. Conserved patterns in the 51p1-encoded immunoglobulin M of normal B cells suggest a restricted sequence repertoire shaped by evolution to recognize common pathogens. Proliferative pressure on these cells is the likely route to U-CLL.

Intrinsic and extrinsic factors influencing the clinical course of B-cell chronic lymphocytic leukemia: prognostic markers with pathogenetic relevance

B-cell chronic lymphocytic leukemia (CLL), the most frequent leukemia in the Western world, is characterized by extremely variable clinical courses with survivals ranging from 1 to more than 15 years. The pathogenetic factors playing a key role in defining the biological features of CLL cells, hence eventually influencing the clinical aggressiveness of the disease, are here divided into "intrinsic factors", mainly genomic alterations of CLL cells, and "extrinsic factors", responsible for direct microenvironmental interactions of CLL cells; the latter group includes interactions of CLL cells occurring via the surface B cell receptor (BCR) and dependent to specific molecular features of the BCR itself and/or to the presence of the BCR-associated molecule ZAP-70, or via other non-BCR-dependent interactions, e.g. specific receptor/ligand interactions, such as CD38/CD31 or CD49d/VCAM-1. A putative final model, discussing the pathogenesis and the clinicobiological features of CLL in relationship of these factors, is also provided.

Relative seroprevalence of human herpes viruses in patients with chronic lymphocytic leukaemia

BACKGROUND

Herpes virus infections may have a significant role in chronic lymphocytic leukaemia (CLL) due to their ability to modulate the host's immune system.

MATERIALS AND METHODS

We examined the seroprevalence of four herpes viruses [Cytomegalovirus (CMV), Epstein-Barr Virus (EBV), human herpes virus (HHV)-6 and -7] in a cohort of European CLL patients (cohort 1, n = 100) in relation to the immunoglobulin variable heavy (IGHV) chain gene use and compared serological results with those obtained from age- and gender-matched healthy adults (n = 100).

RESULTS

CMV-seroprevalence was significantly higher in CLL cohort 1 (79%) than in the control cohort (57%, P = 0.001); the seroprevalence of EBV (89% vs. 94%), HHV-6 (73% vs. 60%), or HHV-7 (35% vs. 35%) was not. In CLL cohort 1, use of IGHV3-30 was more prevalent among CMV-seropositive and of IGHV3-21 among HHV-7-seronegative cases. To investigate the generalizability of these findings, we investigated the herpes virus seroprevalence in a second cohort of age-matched CLL patients from a different geographical area (USA, n = 100, cohort 2). In cohort 2, CMV-seroprevalence was comparable with that of the control cohort (53%). Seroprevalence of EBV, HHV-6 and HHV-7 were 85%, 88% and 73% respectively. In CLL cohort 2, use of IGHV3-30 or IGHV3-21 was not associated with any of the herpes viruses investigated.

CONCLUSIONS

CMV-seropositivity is associated with CLL in selected patient cohorts. However, the considerable variation in herpes virus-specific seropositivity between geographically distinct CLL cohorts indicates that seropositivity for any of the four human herpes viruses investigated is not generally associated with CLL.

Use of similar immunoglobulin VH gene segments by MALT lymphomas of the ocular adnexa

Extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue type (MALT lymphomas) develop from acquired reactive infiltrates directed against external or autoantigens. Although some European cases of ocular adnexal MALT lymphoma have been associated with Chlamydia psittaci infections, C. psittaci has not been detected in large studies of US-based cases. To evaluate whether the growth of US-based ocular adnexal MALT lymphomas may be promoted by a similar antigen, we identified and analyzed the expressed immunoglobulin VH genes in 10 cases. Interestingly, the VH genes in two cases used the same VH1 family V1-2 gene segment, and three cases used the same VH4 family V4-34 gene segment. The other five cases all used different gene segments V4-31, V5-51, V3-23, V3-30, and V3-7. All of the VH genes were mutated from germ line, with percent homologies ranging between 96.9 and 89.0%. The distribution of replacement and silent mutations within the VH genes was nonrandom consistent with the maintenance of immunoglobulin function and also strongly suggestive of antigen selection in the six VH genes with highest mutation loads. The CDR3 sequences in two of three VH-34 cases were the same size (15 amino acids) and had similar sizes in the two VH1-2 cases (18 and 16 amino acids). In conclusion, US-based MALT lymphomas of the ocular adnexa preferentially express a limited set of VH gene segments not frequently used by other MALT lymphomas and consistent with some recognizing similar antigens. Analysis of somatic mutations present within the VH genes is also consistent with antigen binding stimulating the growth of these lymphomas.

The prognosis of clinical monoclonal B cell lymphocytosis differs from prognosis of Rai 0 chronic lymphocytic leukaemia and is recapitulated by biological risk factors

Monoclonal B-cell lymphocytosis (MBL) is an asymptomatic monoclonal expansion of <5.0 x 10(9)/l circulating CLL-phenotype B-cells. The relationship between MBL and Rai 0 CLL, as well as the impact of biological risk factors on MBL prognosis, are unknown. Out of 460 B-cell expansions with CLL-phenotype, 123 clinical MBL (cMBL) were compared to 154 Rai 0 CLL according to clinical and biological profile and outcome. cMBL had better humoral immune capacity and lower infection risk, lower prevalence of del11q22-q23/del17p13 and TP53 mutations, slower lymphocyte doubling time, and longer treatment-free survival. Also, cMBL diagnosis was a protective factor for treatment risk. Despite these favourable features, all cMBL were projected to progress, and lymphocytes <1.2 x 10(9)/l and >3.7 x 10(9)/l were the best thresholds predicting the lowest and highest risk of progression to CLL. Although IGHV status, CD38 and CD49d expression, and fluorescence in situ hybridization (FISH) karyotype individually predicted treatment-free survival, multivariate analysis identified the presence of +12 or del17p13 as the sole independent predictor of treatment requirement in cMBL (Hazard ratio: 5.39, 95% confidence interval 1.98-14.44, P = 0.001). Overall, these data showed that cMBL has a more favourable clinical course than Rai 0 CLL. Given that the biological profile can predict treatment requirement, stratification based on biological prognosticators may be helpful for cMBL management.

Gene expression profile of bladder tissue of patients with ulcerative interstitial cystitis

Background

Interstitial cystitis (IC), a chronic bladder disease with an increasing incidence, is diagnosed using subjective symptoms in combination with cystoscopic and histological evidence. By cystoscopic examination, IC can be classified into an ulcerative and a non-ulcerative subtype. To better understand this debilitating disease on a molecular level, a comparative gene expression profile of bladder biopsies from patients with ulcerative IC and control patients has been performed.

Results

Gene expression profiles from bladder biopsies of five patients with ulcerative IC and six control patients were generated using Affymetrix GeneChip expression arrays (Affymetrix – GeneChip^® Human Genome U133 Plus 2.0). More than 31,000 of > 54,000 tested probe sets were present (detection p-value < 0.05). The difference between the two groups was significant for over 3,500 signals (t-test p-value < 0.01), and approximately 2,000 of the signals (corresponding to approximately 1,000 genes) showed an IC-to-healthy expression ratio greater than two. The IC pattern had similarities to patterns from immune system, lymphatic, and autoimmune diseases. The dominant biological processes were the immune and inflammatory responses. Many of the up-regulated genes were expressed in leukocytes, suggesting that leukocyte invasion into the bladder wall is a dominant feature of ulcerative IC. Histopathological data supported these findings.

Conclusion

GeneChip expression arrays present a global picture of ulcerative IC and provide us with a series of marker genes characteristic for this subtype of the disease. Evaluation of biopsies from other bladder patients with similar symptoms (e.g. patients with non-ulcerative IC) will further indicate whether the data presented here will be valuable for the diagnosis of IC.

Characterization of immunoglobulin heavy and light chain gene expression in chronic lymphocytic leukemia and related disorders

The incidence of chronic lymphocytic leukemia is low in the Japanese population compared with populations in western countries, suggesting a role for genetic factors in the occurrence of this disease. We have previously shown that chronic lymphocytic leukemia in Japan rarely expresses the immunoglobulin heavy chain variable region (IGHV) 1-69 gene (1 out of 43 patients, 2.3%), which is a gene most commonly expressed in chronic lymphocytic leukemia cases from western countries. In the current study, we extended the previous study by examining immunoglobulin heavy chain and light chain gene expression in 80 Japanese patients with chronic lymphocytic leukemia and in 52 Japanese patients with other leukemic chronic lymphoproliferative disorders. IGHV1-69 gene expression was again quite low in our cohort, found in only two patients: one with chronic lymphocytic leukemia and the other with splenic marginal zone lymphoma. The IGHV4-34 gene was most frequently expressed in chronic lymphocytic leukemia (27.5%), whereas it was rarely found in leukemic chronic lymphoproliferative disorders (7.7%, P = 0.005). There was also a significant difference in the expression of IGLV3-21 between chronic lymphocytic leukemia and leukemic chronic lymphoproliferative disorders (29.4 vs 4.8%, P = 0.018). The IGLV3-21 gene in the majority of chronic lymphocytic leukemia cases was associated with homologous complementarity determining region 3 sequences. Recent studies identified subsets of cases expressing almost identical B-cell receptors. We found that two patients with chronic lymphocytic leukemia and the patient with splenic marginal zone lymphoma expressed IGHV4-39/IGKV1-39 and IGHV1-69/IGKV3-20, respectively, which belong to these subsets.

Molecular and clinical features of chronic lymphocytic leukaemia with stereotyped B cell receptors: results from an Italian multicentre study

A fraction of chronic lymphocytic leukaemia (CLL) cases carry highly homologous B-cell receptors (BCR), i.e. characterized by non-random combinations of immunoglobulin heavy-chain variable (IGHV) genes and heavy-chain complementarity determining region-3 (HCDR3), often associated with a restricted selection of IGVK/L light chains. Such 'stereotyped' BCR occur more frequently in CLL with unmutated (UM) than mutated (M) IGHV genes. We analysed 1426 IG rearrangements (from 1398 CLL cases) by a clustering driven by HCDR3 similarities. Molecular findings were correlated to time-to-treatment (TTT) and presence of known prognosticators. Sixty-nine clusters (319 IG-rearrangements, 22.4%) with stereotyped BCR were identified. Among 30 confirmed clusters (>or=3 IG-rearrangements/cluster), we found 14 novel clusters, of which 11 had M IG rearrangements (M clusters) and predominantly (8/11) used IGHV3 subgroup genes. Recurrent cluster-biased amino acid changes were found throughout IGHV sequences of these 'M clusters'. Regarding clinical outcome: (i) UM CLL from the IGHV1-2/1-3/1-18/1-46/7-4-1/IGKV1-39 cluster had poorer prognosis than UM/M cases, or UM cases using the same IGHV genes but not in clusters; (ii) M CLL from the IGHV3-21/IGLV3-21 cluster had TTT similar to UM CLL, and shorter than M CLL expressing IGHV3-21 but not in cluster. Altogether, our analysis identified additional molecular and clinical features for CLL expressing stereotyped BCR.

Use of IGHV3-21 in chronic lymphocytic leukemia is associated with high-risk disease and reflects antigen-driven, post-germinal center leukemogenic selection

We examined the chronic lymphocytic leukemia (CLL) cells of 2457 patients evaluated by the CLL Research Consortium (CRC) and found that 63 (2.6%) expressed immunoglobulin (Ig) encoded by the Ig heavy-chain-variable-region gene (IGHV), IGHV3-21. We identified the amino acid sequence DANGMDV (motif-1) or DPSFYSSSWTLFDY (motif-2) in the Ig heavy-chain (IgH) third complementarity-determining region (HCDR3) of IgH, respectively, used by 25 or 3 cases. The IgH with HCDR3 motif-1 or motif-2, respectively, was paired with Ig light chains (IgL) encoded by IGLV3-21 or IGKV3-20, suggesting that these Ig had been selected for binding to conventional antigen(s). Cases that had HCDR3 motif-1 had a median time from diagnosis to initial therapy comparable with that of cases without a defined HCDR3 motif, as did cases that used mutated IGHV3-21 (n = 27) versus unmutated IGHV3-21 (n = 30). Of 7 examined cases that used Ig encoded by IGHV3-21/IGLV3-21, we found that 5 had a functionally rearranged IGKV allele that apparently had incurred antigendriven somatic mutations and subsequent rearrangement with KDE. This study reveals that CLL cells expressing IGHV3-21/IGLV3-21 most likely were derived from B cells that had experienced somatic mutation and germinal-center maturation in an apparent antigen-driven immune response before undergoing Ig-receptor editing and after germinal-center leukemogenic selection.