VH gene usage by family members affected with chronic lymphocytic leukaemia

IgGeneUsage: differential gene usage in immune repertoires

SUMMARY

Decoding the properties of immune repertoires is key to understanding the adaptive immune response to challenges such as viral infection. One important quantitative property is differential usage of Ig genes between biological conditions. Yet, most analyses for differential Ig gene usage are performed qualitatively or with inadequate statistical methods. Here we introduce IgGeneUsage, a computational tool for the analysis of differential Ig gene usage. IgGeneUsage employs Bayesian inference with hierarchical models to analyze complex gene usage data from high-throughput sequencing experiments of immune repertoires. It quantifies differential Ig gene usage probabilistically and avoids some common problems related to the current practice of null-hypothesis significance testing.

AVAILABILITY AND IMPLEMENTATION

IgGeneUsage is an R-package freely available as part of Bioconductor at: https://bioconductor.org/packages/IgGeneUsage/.

CONTACT

simo.kitanovski@uni-due.de.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Association of elevated serumfree light chains with chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis

Chronic lymphocytic leukemia (CLL) and its precursor, monoclonal B-cell lymphocytosis (MBL), are heritable. Serumfree light-chain (sFLC) measures are a prognostic factor for CLL, but their role in susceptibility to CLL is not clear. We investigated differences between sFLC measurements in pre-treatment serum from five groups to inform the association of sFLC with familial and sporadic CLL: (1) familial CLL (n = 154), (2) sporadic CLL (n = 302), (3) familial MBL (n = 87), (4) unaffected first-degree relatives from CLL/MBL families (n = 263), and (5) reference population (n = 15,396). The percent of individuals having elevated monoclonal and polyclonal sFLCs was compared using age-stratified and age- and sex-adjusted logistic regression models. In age groups >50 years, monoclonal sFLC elevations were increased in sporadic and familial CLL cases compared to the reference population (p's < 0.05). However, there were no statistically significant differences in sFLC monoclonal or polyclonal elevations between familial and sporadic CLL cases (p's > 0.05). Unaffected relatives and MBL cases from CLL/MBL families, ages >60 years, showed elevated monoclonal sFLC, compared to the reference population (p's < 0.05). This is the first study to demonstrate monoclonal sFLC elevations in CLL cases compared to controls. Monoclonal sFLC levels may provide additional risk information in relatives of CLL probands.

Determination of VH Family Usage in B-Cell Malignancies via the BIOMED-2 IGH PCR Clonality Assay

OBJECTIVES

To determine whether V H family usage in B-cell lymphoproliferative disorders can be deduced from polymerase chain reaction (PCR) product-length information obtained through the BIOMED-2 (Invivoscribe, San Diego, CA) clonality assay.

METHODS

We develop an algorithm that uses the sizing information of the BIOMED-2 immunoglobulin heavy chain (IGH) clonality assay to deduce V H family usage. PCR with family-specific primers on 51 clinical samples containing 54 rearranged alleles were used to validate the algorithm.

RESULTS

The clonal PCR products in different framework reactions contain the same NDN segment (because they are from the same allele). Subtracting the size of the framework III product from the size of the framework I and II products yields the relative position of the framework primer binding sites for the V H segment used. The V H family can be assigned with these relative positions because they are V H family specific in the BIOMED-2 assay. The V H family assigned by the algorithm was concordant with family-specific PCR results for 49 (96%) of the 51 specimens.

CONCLUSIONS

We have developed an algorithm that can correctly assign V H family usage when all three BIOMED-2 framework reactions produced clonal products. Given the wide adoption of BIOMED-2 assay, the algorithm can facilitate collection of IGH V H usage data without additional cost to the laboratories.

Comparative study of IgA VH 3 gene usage in healthy TST(-) and TST(+) population exposed to tuberculosis: deep sequencing analysis

The acquired immune response against tuberculosis is commonly associated with T-cell responses with little known about the role of B cells or antibodies. There have been suggestions that B cells and humoral immunity can modulate the immune response to Mycobacterium tuberculosis. However, the mechanisms involving B-cell responses in M. tuberculosis are not fully understood, in particular the antibody gene preferences. We hypothesized that a preferential use of V genes can be seen associated with resistance to infection mainly in the IgA isotype, which is of prominent importance for infection by pathogens via the mucosal route. We studied healthy individuals with long-term exposure to tuberculosis, infected (TST(+) ) and uninfected TST(-) ) with M. tuberculosis. From a total of 22 V genes analysed, the TST(-) population preferred the VH 3-23 and Vκ1 genes. The VH 3-23 genes were subsequently subjected to 454 amplicon sequencing. The TST(-) population showed a higher frequency of the D3-10 segment compared with the D3-22 segment for the TST(+) population. The J segment usage pattern was similar for both populations with J4 segment being used the most. A preferential pairing of J4 segments to D3-3 was seen for the TST(-) population. The antibodyome difference between both populations suggests a preference for antibodies with VH 3-23, D3-3, JH 4 gene usage by the TST(-) population that could be associated with resistance to infection with M. tuberculosis.

"Role of the B-cell receptor and the microenvironment in chronic lymphocytic leukemia''

Despite significant progress in treatment, chronic lymphocytic leukemia (CLL) remains an incurable disease. Advances have been made to understand the molecular pathogenesis underlying CLL progression and treatment resistance. We here review the available evidences concerning the role of the B-cell receptor (BCR) and the tumor microenvironment interactions in CLL pathogenesis. Antigen likely has a key role in the selection of the tumoral clone, the mutational status of immunoglobulin genes is a strong prognostic predictor and BCR signaling has been postulated to have a role for CLL trafficking and interaction with the stromal microenvironment. There is also important evidence, favoring a role for the microenvironment in CLL pathogenesis. Most, if not all, proliferative events occur in the lymph nodes and bone marrow, where leukemic cells receive through microenvironment interactions survival signals aiming to avoid apoptosis and acquire favorable tumoral growing conditions. In addition, the tumoral microenvironment appears to be the site where the acquisition of additional genetic lesions in the clone occur, which should greatly influence clinical outcome. The advent of new tyrosine kinase inhibitors which seem to be able to modulate microenvironment interactions and circumvent the p53 deletion have generated significant promise by raising the possibility that they could provide significant progress in disease treatment.

Inherited susceptibility to chronic lymphocytic leukemia: evidence and prospects for the future

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the United States and one of the most heritable cancers. A family history of the disease is perhaps the best defined risk factor, and approximately 15-20% of CLL patients have a family member with CLL or a related lymphoproliferative disorder. Much effort has been devoted to trying to elucidate the mechanisms underlying this genetic risk. Familial CLL appears to be clinically and biologically similar to sporadic CLL, and most if not all CLL appears to be preceded by monoclonal B-cell lymphocytosis (MBL), which does appear to occur at higher frequency in relatives in families with CLL. Neither linkage studies nor candidate gene association studies have proven particularly informative in CLL, but genomewide association studies have identified multiple low-risk variants that together explain about 16% of the familial risk of CLL. Studies of individual families have identified higher-risk single nucleotide polymorphisms or copy number variants associated with disease risk in those families. Current efforts to identify additional risk loci are focused on applying next-generation sequencing to the germline of informative CLL families as well as individuals with sporadic CLL.

Inherited predisposition to chronic lymphocytic leukemia

Inherited susceptibility to chronic lymphocytic leukemia (CLL) has been recognized for decades. Approximately 10% of individuals with CLL report a family history of CLL or a related lymphoproliferative disorder, and genetic predisposition is the best understood risk factor for CLL. Studies of familial CLL have suggested that the disease features are largely similar to sporadic CLL, although recent data suggest that familial CLL may more commonly show somatic hypermutation of the immunoglobulin heavy-chain variable region, suggesting a more indolent disease course. Monoclonal B-cell lymphocytosis (MBL) has been identified recently as a likely precursor to CLL; it is found in the general population with increasing age and enriched in unaffected relatives of individuals with familial CLL. Studies of MBL as well as mouse models of CLL may lead to better understanding of early CLL pathogenesis that is relevant to familial predisposition. To date, the identification of genes that predispose to familial CLL has been slow, primarily due to the relatively few families available for study, the small size of those families and disease causation most likely by multiple genes that each confer smaller risks. In the coming years, the application of systematic genomics approaches to familial CLL should, hopefully, lead to the identification of novel loci involved in the disease.

Cellular origin(s) of chronic lymphocytic leukemia: cautionary notes and additional considerations and possibilities

Several cell types have been suggested as giving rise to chronic lymphocytic leukemia (CLL), and these suggestions have reflected the sophistication of technology available at the time. Although there is no consensus as to the normal cellular counterpart(s) in the disease, an antigen-experienced B lymphocyte appears required based on surface membrane phenotypes and gene expression profiles. However, what is still unclear is whether a single or multiple normal precursors were stimulated to evolve into CLL and at what stage(s) this occurred. A unifying, parsimonious theory is that CLL clones with either mutated or unmutated IGHVs derive from marginal zone B cells. However, evidence for remarkably similar B-cell receptor amino acid sequence and striking differences in polyantigen and autoantigen-binding activity, found in some but not all CLL clones, challenge a single-cell derivation for CLL. In this Perspective, we summarize data regarding normal counterparts of CLL cells and suggest that a multistep process of leukemogenesis is important to consider when assigning a cellular origin for this disease. Finally, although available data do not definitively identify the cell(s) of origin, we offer possibilities for single- and multiple-cell origin models as straw men that can be improved on and hopefully lead to final answers to this puzzle.

Immunoglobulin heavy chain V-D-J gene rearrangement and mutational status in Uruguayan patients with chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (CLL) is characterized by the accumulation of long-lived circulating clonal leukemic B-cells, although the etiopathogenesis remains unclear. The incidence of CLL is variable in different regions around the world. While it is the most frequent chronic leukemia in Western countries, it has a low incidence in Asia. In this work we have investigated the immunoglobulin heavy chain gene rearrangements and mutational status in 80 Uruguayan patients with CLL, and compared these results with those obtained in other geographic regions. Our results demonstrate that Uruguayan patients with CLL display an IGHV gene usage which resembles that observed in Mediterranean countries and exhibits certain differences compared with Brazilian and Asian series, as expected, considering the ethnic basis of the Uruguayan population. This suggests that genetic influences could be important in the development and etiopathogenesis of CLL, but larger studies are necessary to substantiate this possibility.

Analysis of the immunoglobulin heavy chain variable region gene expression in Iranian patients with chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (B-CLL) results from clonal expansion of phenotypically mature but functionally immature B-lymphocytes. The incidence of this type of leukemia is low in Asian countries, whereas it is the most frequent type of leukemia in the West. Previous investigations mainly conducted in Western populations have demonstrated non-random rearrangement of certain immunoglobulin variable region heavy (VH) and/or light (VL) chain genes in different groups of B-CLL patients. Little is known about the profile of VH gene expression in Asian patients. In the present study, we determined the frequency of VH gene family usage in 59 Iranian patients with B-CLL. VH gene family of patients was determined by reverse transcriptase-polymerase chain reaction using VH1-VH7 family specific primers. The most frequently expressed VH gene family was found to be VH3 (45.8%) followed by VH4 (32.2%), VH1 (18.6%), VH5 (1.7%) and VH6 (1.7%), with no expression of VH2 and VH7 gene families. The results indicate a lower representation of the VH1 and VH2 gene families and a higher representation of the VH4 gene family in Iranian B-CLL patients compared to Western patients, suggesting involvement of ethnic and/or environmental factors in B-CLL disease initiation.

Familial chronic lymphocytic leukemia

The role of inherited genetic factors in the etiology of chronic lymphocytic leukemia (CLL) and other B-cell lymphoproliferative disorders is now well established. Significant familial aggregation of CLL and B-cell lymphoproliferative disorders has been demonstrated, but the mode of inheritance is unknown. Identification of genes that when mutated confer an increased risk of these diseases is of immediate clinical relevance because it may offer clues to pathogenesis and highlight possible therapeutic targets. Furthermore, identification of these genes provides a greater understanding of the mechanisms of B-cell tumorigenesis in general. This article reviews current knowledge relating to inherited susceptibility to CLL and strategies that are being used to identify disease-causing mutations.

Insight into the pathogenesis of chronic lymphocytic leukemia (CLL) through analysis of IgVH gene usage and mutation status in familial CLL

To address the proposition that familial B-cell chronic lymphocytic leukemia (CLL) may exhibit a more restricted phenotype than sporadic CLL with respect to immunoglobulin gene usage or ontogenic development, we compared immunoglobulin (Ig) heavy chain variable region (VH) gene usage and IgVH mutation status in 327 patients with CLL from 214 families with 724 patients with sporadic cases. The frequency of mutated CLL was higher in familial CLL (P < .001), and there was evidence of intrafamilial concordance in mutation status (P < .001). The repertoire and frequency of IgVH usage was, however, not significantly different between familial and sporadic CLL. Furthermore, IgVH usage was not correlated between affected members of the same family. These observations provide evidence that familial CLL is essentially indistinguishable from sporadic CLL, favoring a genetic basis to disease development in general rather than a simple environmental etiology.

Analysis of a large multi-generational family provides insight into the genetics of chronic lymphocytic leukemia

We report the genetic analysis of a large multi-generational family composed of 144 individuals in which 11 members have been diagnosed with chronic lymphocytic leukaemia (CLL). The observation of a significant over-representation of monoclonal B-cell lymphocytosis (MBL) in unaffected family members strongly supports MBL being a surrogate marker of carrier status. A genome-wide linkage scan of the family using high-density 10K single nucleotide polymorphisms provided no significant evidence for a single gene model of disease susceptibility, inviting speculation that susceptibility to CLL has a more complex basis. The absence of a correlation in IGHV usage between affected family members does however argue strongly against exposure to a single super-antigen in disease development.

Germline mutations in RAD51, RAD51AP1, RAD51B, RAD51C,RAD51D, RAD52 and RAD54L do not contribute to familial chronic lymphocytic leukemia

While familial predisposition to B-cell chronic lymphocytic leukemia (CLL) is well recognized no gene which when mutated in the germline has been unambiguously shown to confer susceptibility to the disease. An approach based on mutation screening methods targeted to coding regions of candidate genes offers an attractive strategy for the identification of rare disease-causing alleles. The RAD genes participate in the cellular response to DNA double strand breaks, detecting DNA damage, activating cell cycle checkpoints and apoptosis. Defects in members of these genes are linked to increased chromosomal instability and in lymphoma predisposition, thereby representing strong candidate susceptibility genes a priori. To examine this proposition we screened 75 familial CLL probands for germline mutations in this set of genes. No overt pathogenic mutations were identified. These findings indicate that germline mutations in RAD51, RAD51AP1, RAD51L1, RAD51L3, RAD52 and RAD54L are unlikely to be causal of an inherited predisposition to CLL.

Genetic alteration associated with chronic lymphocytic leukemia

The genetics of B-cell chronic lymphocytic leukemia (B-CLL) differ considerably from most other forms of hematologic malignancy which are usually characterized by chromosome translocations. B-CLL typically contains chromosomal deletions and chromosomes 13q14 and 11q22-->q23 are the most common. These two regions appear to share a common ancestral origin (Auer et al., 2007b). Overall, chromosomal abnormalities can be found in the majority of patients with B-CLL when using sensitive techniques (Dohneret al., 2000) and possibly reflects an underlying predisposition, with a small but significant number of familial cases. Although single and consistent abnormalities are most common, multiple rearrangements can occur, often with disease progression (Feganetal., 1995; Dohner et al., 2000). Regions of recurrent deletion suggest the presence of tumor suppressor genes if following Knudson's theoretical 2-hit model. However, despite extensive sequencing analysis over the last decade and lack of pathogenic mutations identified, there has been a move away from this suggested hypothesis and alternative mechanisms of gene inactivation involving epigenetic silencing or haploinsufficiency may be considered as more likely in this disease. This review focuses on the common genetic abnormalities in B-CLL and relates them to some of the more recent hypotheses on inactivation of genes within these regions of deletion.

Drp1 mediates caspase-independent type III cell death in normal and leukemic cells

Ligation of CD47 triggers caspase-independent programmed cell death (PCD) in normal and leukemic cells. Here, we characterize the morphological and biochemical features of this type of death and show that it displays the hallmarks of type III PCD. A molecular and biochemical approach has led us to identify a key mediator of this type of death, dynamin-related protein 1 (Drp1). CD47 ligation induces Drp1 translocation from cytosol to mitochondria, a process controlled by chymotrypsin-like serine proteases. Once in mitochondria, Drp1 provokes an impairment of the mitochondrial electron transport chain, which results in dissipation of mitochondrial transmembrane potential, reactive oxygen species generation, and a drop in ATP levels. Surprisingly, neither the activation of the most representative proapoptotic members of the Bcl-2 family, such as Bax or Bak, nor the release of apoptogenic proteins AIF (apoptosis-inducing factor), cytochrome c, endonuclease G (EndoG), Omi/HtrA2, or Smac/DIABLO from mitochondria to cytosol is observed. Responsiveness of cells to CD47 ligation increases following Drp1 overexpression, while Drp1 downregulation confers resistance to CD47-mediated death. Importantly, in B-cell chronic lymphocytic leukemia cells, mRNA levels of Drp1 strongly correlate with death sensitivity. Thus, this previously unknown mechanism controlling caspase-independent type III PCD may provide the basis for novel therapeutic approaches to overcome apoptotic avoidance in malignant cells.

Chronic lymphocytic leukemia: diagnosis and treatment

Traditionally, the goal of therapy in chronic lymphocytic leukemia (CLL) has been palliative, with first-line therapy using alkylating agents and/or involved field radiotherapy (depending on the stage of disease and sites of involvement) because of the older age of affected patients and the low rate of complete remissions (CRs) with no improvement in overall survival despite treatment. With increasing knowledge about the biology, molecular genetics, and prognostic factors of the disease, the philosophy of care for patients with CLL has evolved from palliation to aiming for a potential cure, especially in younger patients. Furthermore, multiple treatment options have emerged, including purine analogues, monoclonal antibodies, and potentially stem cell transplantation. These have been associated with higher frequencies of CRs and longer durations of responses compared to conventional chemotherapy. In addition, a subset of patients treated with chemoimmunotherapy can achieve durable CRs and molecular remissions. This may translate into improved disease-free survival and potentially a "cure." Because of the heterogeneous nature of CLL, new prognostic markers are currently being incorporated into clinical trials to determine their role in routine clinical practice. This review summarizes current therapeutic regimens that are being evaluated in patients with CLL and management of disease-related complications.

Structural and Functional Features of the B-Cell Receptor in IgG-Positive Chronic Lymphocytic Leukemia

PURPOSE

To determine the origin and relationship of the rare IgG+ variant of chronic lymphocytic leukemia (CLL) to the two common IgM+IgD+ subsets that are distinguished by expression of unmutated or mutated V(H) genes, with the former having a worse prognosis.

EXPERIMENTAL DESIGN

IgG+ CLL cells were characterized using phenotypic, functional, and immunogenetic analyses.

RESULTS

IgG+ CLL was phenotypically similar to mutated IgM+IgD+ CLL (M-CLL) and variably expressed CD38 (4 of 14). ZAP-70, a tyrosine kinase preferentially expressed in unmutated CLL, was found in only 2 of 14 cases. The ability to signal via surface IgM (sIgM) varies between the main subsets of CLL and is associated with expression of ZAP-70. In IgG(+) CLL, 9 of 14 responded to engagement of sIgG with no apparent requirement for expression of CD38 or ZAP-70. However, signal capacity correlated with intensity of sIgG expression. Most switched immunoglobulin variable region genes were somatically mutated without intraclonal variation, and no case expressed activation-induced cytidine deaminase. Derivation from a postgerminal center B cell is, therefore, likely, and a relationship with M-CLL is suggested. This is supported by a shared biased usage of the V4-34 gene. Similar bias in normal B cells developed with age, providing an expanded population for transforming events. However, conserved sequences detected in the CDR3 of V4-34-encoded gamma chains were not found M-CLL, indicating no direct path of isotype switch from M-CLL.

CONCLUSION

IgG+ CLL is likely to arise from an age-related expanded pool of B cells, on a path parallel to M-CLL, and perhaps with a similar clinical course.

Clinical and laboratory parameters that define clinically relevant B-CLL subgroups

B cell-type chronic lymphocytic leukemia (B-CLL) is a heterogeneous disease. This is reflected by the very wide-ranging clinical courses that B-CLL patients experience and by the marked variation in laboratory findings between patients. In this chapter, we will review the various clinical and laboratory parameters that divide B-CLL patients into "subgroups," and correlate the parameters that define them. When feasible, we will also link clinical features to the cellular and genetic characteristics recently defined for these leukemic cells. The discussion is limited to parameters that define phenotypes or subgroups that may relate to disease activity and clinical outcome.

Chromosomal aberrations and CD38 expression in two siblings with B-cell chronic lymphocytic leukemia: a report of two siblings

In this study our purpose was to define chromosomal aberrations and CD38 expression in male siblings 69 and 66-years-old with B-cell chronic lymphocytic leukemia (B-CLL). Cells from peripheral blood were analysed by comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). The alteration detectable by CGH was the over-representation of the Y chromosome in both samples. Interphase FISH were performed using locus (13q14 and 17p53) and centromere (chromosome 12, 17 and Y) specific DNA probes. One brother (patient 1, 69 years of age) showed deletion of the 13q14 region, this alteration was associated with low CD38 expression, both predicting a favourable prognosis. However, the younger patient's (patient 2, 66 years of age) cells expressed CD38 in high percent, which is considered as an indicator of poor prognosis, and deletion of the 13q14 was not seen. Other, relatively frequent chromosomal alterations including trisomy 12 and deletion of 17p53 were not present in any of the samples. The cytogenetic findings and the CD38 expression are in concordance with the clinico-pathological data of the siblings. Thus, we found the variability of these parameters described in B-CLL even in the familial form of the disease.

Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936

In a European BIOMED-2 collaborative study, multiplex PCR assays have successfully been developed and standardized for the detection of clonally rearranged immunoglobulin (Ig) and T-cell receptor (TCR) genes and the chromosome aberrations t(11;14) and t(14;18). This has resulted in 107 different primers in only 18 multiplex PCR tubes: three VH-JH, two DH-JH, two Ig kappa (IGK), one Ig lambda (IGL), three TCR beta (TCRB), two TCR gamma (TCRG), one TCR delta (TCRD), three BCL1-Ig heavy chain (IGH), and one BCL2-IGH. The PCR products of Ig/TCR genes can be analyzed for clonality assessment by heteroduplex analysis or GeneScanning. The detection rate of clonal rearrangements using the BIOMED-2 primer sets is unprecedentedly high. This is mainly based on the complementarity of the various BIOMED-2 tubes. In particular, combined application of IGH (VH-JH and DH-JH) and IGK tubes can detect virtually all clonal B-cell proliferations, even in B-cell malignancies with high levels of somatic mutations. The contribution of IGL gene rearrangements seems limited. Combined usage of the TCRB and TCRG tubes detects virtually all clonal T-cell populations, whereas the TCRD tube has added value in case of TCRgammadelta(+) T-cell proliferations. The BIOMED-2 multiplex tubes can now be used for diagnostic clonality studies as well as for the identification of PCR targets suitable for the detection of minimal residual disease.

Binet's staging system and VH genes are independent but complementary prognostic indicators in chronic lymphocytic leukemia

PURPOSE

Rai's and Binet's staging systems have contributed significantly to the identification of major prognostic groups in chronic lymphocytic leukemia (CLL), though they fail to accurately predict disease progression at the individual level. Biologic factors, such as the mutational status of the immunoglobulin heavy-chain variable genes (VH, cytogenetics, CD38 expression, and some serum markers, have recently improved prognostic assessment in CLL. In this study, we analyzed the prognostic value of VH mutational status within the different stages of Binet's classification in 145 patients.

PATIENTS AND METHODS

Our series consisted of 83 VH mutated (MT) and 62 VH unmutated (UM) patients. MT cases predominated within Binet's stage A (70%), whereas UM cases predominated among stages B and C (62%).

RESULTS

Median overall survival (OS) was 84 months for UM patients and was not achieved for the MT group (70% 12-year survival, P <.0001). Concerning Binet's stage A, both median OS and progression-free survival were significantly shorter for UM patients when compared with those of MT patients (97 months v not achieved, P =.0017; and 42 v 156 months, P <.0001), which compared favorably with the classical A' and A" substaging. The VH mutational profile could also segregate stage B and C patients into two groups with different survival patterns (median OS, 78 v 120 months for UM and MT patients, respectively; P =.002).

CONCLUSION

The significant survival differences observed between the VH mutational groups, among stage A and stage B and C patients, indicate that Binet's classification and VH genes are independent prognostic variables and are most likely complementary.

Causation of chronic lymphocytic leukemia--insights from familial disease

In Western countries B-cell chronic lymphocytic leukemia (CLL) is the most common form of leukemia. Evidence from epidemiological studies and family studies strongly supports the notion that a subset of CLL involves inherited susceptibility. Identification of genes predisposing to CLL should be useful for diagnosis and treatment, as well as serving as a model for B-cell tumorigenesis in general. Here, we review the current status of knowledge about inherited susceptibility to CLL.

B cell chronic lymphocytic leukemia: lessons learned from studies of the B cell antigen receptor

B cell chronic lymphocytic leukemia (B-CLL) is an accumulative disease of slowly proliferating CD5(+) B lymphocytes that develops in the aging population. Whereas some patients with B-CLL have an indolent course and die after many years from unrelated causes, others progress very rapidly and succumb within a few years from this currently incurable leukemia. Over the past decade studies of the structure and function of the B cell antigen receptor (BCR) used by these leukemic cells have helped redefine the nature of this disease. In this review we summarize and reinterpret several aspects of these BCR-related studies and how they might relate to the disease. In particular, we address the ability of antigens to select out and drive B cell clones from the normal state to overt leukemic cells by binding to BCRs that are relatively unique and characteristic of B-CLL cells. The differential capacity of some B-CLL cases to continue to transduce signals through the BCR during the leukemic phase and the consequences for the in vivo biology of the leukemic clone is also considered. Finally, we discuss current and emerging views of the cellular origin of B-CLL cells and the differentiation pathways down which we believe these cells progress.

Identification of oligoclonal CD4 T cells in diffuse large B cell lymphomas

Human B cell lymphomas often contain CD4 T cells. Here we show that, in diffuse large B cell lymphomas (DLCL), such T cells are oligoclonal. The CDR3 lengths and nucleotide sequences of oligoclonal TCRBV of CD4 T cells in an original and relapsed lymphoma from one patient were compared. Three BV23 sequences were identical (12/17 and 16/16 clones in primary and relapsed lymphomas, respectively), but were absent in CD4 T cells from another patient's DLCL. Two of the repetitive BV23 sequences were found in peripheral blood CD4 T cells (5/17 clones); gamma-irradiated DLCL from this patient stimulated syngeneic BV23 response in CD4 cells (92% of BV23 had the same CDR3 length). Skew in TCRBV representation was observed in CD4 T cells from all the DLCL. One DLCL, with overrepresentation of BV13S1 in CD4 cells, stimulated the same TCR in CD4 cells from three unrelated individuals. These findings support the conclusion that there is clonal selection of CD4 T cells in DLCL.

Predictive value of serum thymidine kinase level for Ig-V mutational status in B-CLL

In B-CLL IgV(H) genes mutational status is a major prognostic factor. Since sequencing of IgV(H) genes is not available in most laboratories, an easily performed surrogate assay is desirable. To identify the best surrogate assay, and to better discriminate prognostic subgroups we analyzed clinical and biological data from 58 typical CLL cases. A higher serum thymidine kinase level (>15 U/l) proved to be a strong predictor of mutational status, and the only independent one among the studied parameters. To further identify prognostic subgroups, cluster analysis was employed on 38 cases on which all data were available, which segregated two groups including 25 and 13 patients, respectively. These two clusters differed by their proliferative potential and appeared to discriminate patients with very different clinical course and outcome. s-TK was strikingly different among these two clusters, suggesting that s-TK level could be used routinely to identify patients at risk of progression.

Hereditary chronic lymphocytic leukemia: an extended family study and literature review

Leukemia is manifested in about 1-2% of people in Western industrialized nations. The most common form of leukemia is B-cell chronic lymphocytic leukemia (B-CLL), which accounts for approximately 30% of all cases. While CLL's etiology remains elusive, there is increasing evidence that substantially supports the role of hereditary factors in a subset of cases of this disease. Our purpose is to describe an extremely well documented CLL family wherein the disease has been verified in a father and his four sons; two of the sons are identical twins. The family history, including available medical records and pathology reports, was gathered and reviewed. Peripheral blood lymphocytes were used for cytogenetic and fluorescence in situ hybridization analyses. The family reported herein shows classic findings in support of an autosomal dominant mode of genetic transmission of CLL. Given the explosive developments in molecular genetics during the past decade, it is certain that families of this type will provide important clues to the etiology, pathogenesis, and ultimate prevention of CLL.

Instability of CAG-trinucleotide repeats in chronic lymphocytic leukemia

Anticipation--earlier onset and more severe disease in the offspring generation--is a well documented feature of familial chronic lymphocytic leukaemia (CLL). In a number of Mendelian diseases, anticipation is caused by expansion of contiguous triplets of nucleotides. The severity of disease expression and penetrance is related to the extent of the triplet expansion. To investigate whether repeat nucleotide repeat expansion is a feature of CLL, the repeat expansion detection (RED) technique was applied to samples from 17 patients with familial disease and 32 patients with early-onset CLL disease. No potentially pathological CAG expansions were detected. We conclude that unstable CAG repeat expansion is not a feature of CLL and that other processes are likely to be involved in generating anticipation in familial forms of the disease.

Genetic susceptibility to chronic lymphocytic leukemia

There is increasing evidence that a subset of chronic lymphocytic leukemia is caused by an inherited predisposition. Here we review the evidence for an inherited predisposition, the characteristics of familial cases and evidence for the involvement of specific genes.

Anticipation in familial chronic lymphocytic leukaemia

Anticipation, a phenomenon in which an inherited disease is diagnosed at an earlier age in each successive generation of a family, has been demonstrated in certain heritable neurological disorders and in multiple myeloma, non-Hodgkin's lymphoma and other haematological neoplasms. The present study was conducted to determine whether anticipation occurs in familial chronic lymphocytic leukaemia (CLL). Fourteen published reports of multigenerational familial CLL were analysed for anticipation, together with 10 previously unreported families with familial CLL, and the difference in disease-free survival between generations was determined. The difference between age at onset for each affected parent-child pair was tested against the null hypothesis that there was no difference in age at onset. The age at onset of the studied cases was also compared with that of the Surveillance Epidemiology and End Results (SEER) Program of the U.S. National Cancer Institute. The median ages at onset in the child and parent generations of all families (51.0 and 72.0 years respectively) were significantly different (P < 0.000001), and the null hypothesis was rejected (P < 0.000001). A significant difference was observed between the ages of onset of the child generation and the SEER population (P < 0.00001), but not between the parent generation and the SEER population. Anticipation characterizes familial CLL.

Clinical relevance of immunoglobulin mutation analysis

The precise diagnosis of malignant B-cell lymphoproliferations is essential for their appropriate clinical management. Histologic and immunophenotypical features alone are often insufficient in discriminating between various lymphoma entities and subtypes. The analysis of clonally rearranged immunoglobulin chain genes of the tumor cells was therefore suggested as an additional parameter. This article reviews current knowledge and describes which conclusions can be drawn for lymphoma diagnosis based on the type of immunoglobulin chain gene rearrangement, as well as on the number and distribution of somatic immunoglobulin mutations. Although there are striking correlations between the clinical outcome and the immunoglobulin mutations in some entities, many additional studies are required in order to draw final conclusions for most types of lymphoma.