Landscape of <i>immunoglobulin heavy chain gamma</i> gene class switch recombination in patients with adult T-cell leukemia–lymphoma

Not available.

Lymphoma-like monoclonal B cell lymphocytosis in a patient population: biology, natural evolution, and differences from CLL-like clones

High-count monoclonal B cell lymphocytosis (MBL) with a chronic lymphocytic leukemia (CLL) phenotype is a well-known entity, featuring 1-4% annual risk of progression towards CLL requiring treatment. Lymphoma-like MBL (L-MBL), on the other hand, remains poorly defined and data regarding outcome are lacking. We retrospectively evaluated 33 L-MBL cases within our hospital population and compared them to 95 subjects with CLL-like MBL (C-MBL). Diagnoses of L-MBL were based on asymptomatic B cell clones with Matutes score < 3, B cells < 5.0 × 10³/μl, and negative computerized tomography scans. We found that median B cell counts were considerably lower compared to C-MBL (0.6 vs 2.3 × 10³/μl) and remained stable over time. Based on immunophenotyping and immunogenetic profiling, most L-MBL clones did not correspond to known lymphoma entities. A strikingly high occurrence of paraproteinemia (48%), hypogammaglobulinemia (45%), and biclonality (21%) was seen; these incidences being significantly higher than in C-MBL (17, 21, and 5%, respectively). Unrelated monoclonal gammopathy of undetermined significance was a frequent feature, as the light chain type of 5/12 paraproteins detected was different from the clonal surface immunoglobulin. After 46-month median follow-up, 2/24 patients (8%) had progressed towards indolent lymphoma requiring no treatment. In contrast, 41% of C-MBL cases evolved to CLL and 17% required treatment. We conclude that clinical L-MBL is characterized by pronounced immune dysregulation and very slow or absent progression, clearly separating it from its CLL-like counterpart.

Preferential use of unmutated immunoglobulin heavy variable region genes in Boxer dogs with chronic lymphocytic leukemia

Human chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease, and immunoglobulin heavy variable region (IGHV) gene mutational status is an important prognostic marker. IGHV mutational status has not been previously examined in canine CLL. We sequenced the IGHV-D-J rearrangements from 55 canine patients with CLL, including 36 non-Boxer and 19 Boxer dogs. The majority of non-Boxers (75%) had mutated IGHV genes, whereas the majority of Boxers (79%) had unmutated IGHV genes. IGHV3-41 and IGHV3-67 gene usage was significantly higher in Boxers with CLL compared to non-Boxers. Additionally, 11 Boxers with large B-cell lymphoma and the normal IGHV repertoire of six control dogs (three Boxers and three non-Boxers) were sequenced. IGHV3-41 was preferentially used in Boxers with other forms of lymphoma and without lymphoproliferative disease. However, preferential use of unmutated IGHV genes was unique to Boxers with CLL, suggesting Boxers may be a valuable model to investigate unmutated CLL.

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.

Recurrent Cytogenetic Abnormalities in Multiple Myeloma

Multiple myeloma is a heterogeneous disease. Its chromosomal abnormalities have been extensively studied with a view to accurate prognostication and personalized therapy. Here, we describe the techniques commonly employed for elucidating chromosomal aberrations, prognostic impact of recurrent chromosomal abnormalities, and recently updated risk stratification systems.

Vaccine-Induced Antibodies that Neutralize Group 1 and Group 2 Influenza A Viruses

Antibodies capable of neutralizing divergent influenza A viruses could form the basis of a universal vaccine. Here, from subjects enrolled in an H5N1 DNA/MIV-prime-boost influenza vaccine trial, we sorted hemagglutinin cross-reactive memory B cells and identified three antibody classes, each capable of neutralizing diverse subtypes of group 1 and group 2 influenza A viruses. Co-crystal structures with hemagglutinin revealed that each class utilized characteristic germline genes and convergent sequence motifs to recognize overlapping epitopes in the hemagglutinin stem. All six analyzed subjects had sequences from at least one multidonor class, and-in half the subjects-multidonor-class sequences were recovered from >40% of cross-reactive B cells. By contrast, these multidonor-class sequences were rare in published antibody datasets. Vaccination with a divergent hemagglutinin can thus increase the frequency of B cells encoding broad influenza A-neutralizing antibodies. We propose the sequence signature-quantified prevalence of these B cells as a metric to guide universal influenza A immunization strategies.

Extranodal Marginal Zone B-Cell Lymphoma/Maltoma of the Lip in a Child

All forms of cutaneous lymphomas are rare in children. Extranodal marginal zone B-cell lymphomas (EMZBL)/mucosa-associated lymphoid tissue (MALT) lymphomas are unusual neoplasms in children and young adults. We report a case of an EMZBL/MALT lymphoma of the lip in a previously healthy 14-year-old boy without immunodeficiency, confirmed by immunohistochemistry and documentation of clonal rearrangement of the immunoglobulin heavy-chain gene. Additionally, we present a review of the differential diagnosis of skin and mucosal lymphoid proliferations in childhood.

Impact of telomere length on survival in classic and variant hairy cell leukemia

Telomeres, which protect the ends of chromosomes, are shortened in several hematologic malignancies, often with adverse prognostic implications, but their effect on prognosis of classic and variant hairy cell leukemia (HCL and HCLv) has not been reported. HCL/HCLv genomic DNA from 46 patients was studied by PCR to determine the ratio of telomere to single copy gene number (T/S). T/S was unrelated to diagnosis of HCL or HCLv (p=0.27), but shorter T/S was associated with unmutated immunoglobulin rearrangements (p=0.033) and age above the median at diagnosis (p=0.017). Low T/S was associated with shorter overall survival from diagnosis (OS), particularly T/S <0.655 (p=0.0064, adjusted p=0.019). Shorter OS was also associated with presence of unmutated (p<0.0001) or IGHV4-34+ (p<0.0001) rearrangements, or increasing age (p=0.0002). Multivariable analysis with Cox modeling showed that short T/S along with either unmutated or IGHV4-34+ rearrangements remained associated with reduced OS (p=0.0071, p=0.0024, respectively) after age adjustment. While T/S is relatively long in HCL and the disease usually indolent with excellent survival, shortened telomeres in HCL/HCLv are associated with decreased survival. Shortened T/S could represent a risk factor needing further investigation/intervention to determine if non-chemotherapy treatment options, in addition to or instead of chemotherapy, might be particularly useful.

Setd1a regulates progenitor B-cell-to-precursor B-cell development through histone H3 lysine 4 trimethylation and Ig heavy-chain rearrangement

SETD1A is a member of trithorax-related histone methyltransferases that methylate lysine 4 at histone H3 (H3K4). We showed previously that Setd1a is required for mesoderm specification and hematopoietic lineage differentiation in vitro. However, it remains unknown whether or not Setd1a controls specific hematopoietic lineage commitment and differentiation during animal development. Here, we reported that homozygous Setd1a knockout (KO) mice are embryonic lethal. Loss of the Setd1a gene in the hematopoietic compartment resulted in a blockage of the progenitor B-cell-to-precursor B-cell development in bone marrow (BM) and B-cell maturation in spleen. The Setd1a-cKO (conditional knockout) mice exhibited an enlarged spleen with disrupted spleen architecture and leukocytopenia. Mechanistically, Setd1a deficiency in BM reduced the levels of H3K4me3 at critical B-cell gene loci, including Pax5 and Rag1/2, which are critical for the IgH (Ig heavy-chain) locus contractions and rearrangement. Subsequently, the differential long-range looped interactions of the enhancer Eμ with proximal 5' DH region and 3' regulatory regions as well as with Pax5-activated intergenic repeat elements and 5' distal VH genes were compromised by the Setd1a-cKO. Together, our findings revealed a critical role of Setd1a and its mediated epigenetic modifications in regulating the IgH rearrangement and B-cell development.

Intravascular large B-cell lymphoma secondary to lymphoplasmacytic lymphoma: a case report and review of literature with clonality analysis

Intravascular large B-cell lymphoma (IVLBCL) can be a fatal malignancy mainly because of difficulty in early detection. Due to the lack of specific clinical manifestations, early detection of IVLBCL remains a challenge, especially in the presence of comorbidities. Lymphoplasmacytic lymphoma (LPL) is an indolent B-cell lymphoma accompanied by monoclonal immunoglobulin M protein in most patients, and known to be associated with high risk of secondary hematological malignancies. Here, we report a patient who developed IVLBCL during treatment for LPL that presented a diagnostic challenge. Rearrangement analysis of the immunoglobulin heavy chain revealed the different clonal origins of two lymphomas, implying a predisposition of LPL to develop unrelated secondary lymphoma. Secondary lymphoma including IVLBCL during the treatment for LPL deserves consideration in order to facilitate early diagnosis and intervention.

Recommendations of the SFH (French Society of Haematology) for the diagnosis, treatment and follow-up of hairy cell leukaemia

Hairy cell leukaemia (HCL) is a rare haematological malignancy, with approximately 175 new incident cases in France. Diagnosis is based on a careful examination of the blood smear and immunophenotyping of the tumour cells, with a panel of four markers being used specifically to screen for hairy cells (CD11c, CD25, CD103 and CD123). In 2011, the V600E mutation of the BRAF gene in exon 15 was identified in HCL; being present in HCL, it is absent in the variant form of HCL (HCL-v) and in splenic red pulp lymphoma (SRPL), two entities related to HCL. The management of patients with HCL has changed in recent years. A poorer response to purine nucleoside analogues (PNAs) is observed in patients with more marked leukocytosis, bulky splenomegaly, an unmutated immunoglobulin variable heavy chain (IgVH) gene profile, use of VH4–34 or with TP53 mutations. We present the recommendations of a group of 11 experts belonging to a number of French hospitals. This group met in November 2013 to examine the criteria for managing patients with HCL. The ideas and proposals of the group are based on a critical analysis of the recommendations already published in the literature and on an analysis of the practices of clinical haematology departments with experience in managing these patients. The first-line treatment uses purine analogues: cladribine or pentostatin. The role of BRAF inhibitors, whether or not combined with MEK inhibitors, is discussed. The panel of French experts proposed recommendations to manage patients with HCL, which can be used in a daily practice.

[Clinical features in DLBCL and translocation BCL2/c-MYC "double hit" lymphoma]

Diffuse large B-cell lymphoma (DLBCL) is classified as lymphoma and various entities using the gene expression of proteins are classified into three groups. The aim of this study was to clarify the clinical, biological, immunophenotypic and cytogenetic features of DLBCL with translocation t (14; 18) and 8q24/c-MYC. Eleven DLBCL patients with dual translation were monitored during the 2000-2009 period. The characteristics of these patients included morphological, immunohistochemical and cytogenetic analysis. Study results showed that all patients had aggressive characteristics, presence of B symptoms (64%), general patient condition according to ECOG scale ≥ 2 (55%), elevated serum lactate dehydrogenase activity (73%), clinical stage III and IV (82%), extranodal involvement of the disease (73%), and IPI ≥ 2 (73%). Partial remission was achieved in 73% of all patients and all patients (73%) died within a short time. Patients were treated with CHOP and similar protocols (COP, CVP, CNOP), with the addition of MabThera. Immunophenotyping was performed and determined expression of the CD20, CD3, CD10, BCL6 and MUM1 markers. The cytogenetic analysis/fluorescence in situ hybridization revealed complex karyotype changes. Thus, we analyzed the presence of BCL2, BCL6 and c-MYC genes and found eight patients to have BCL2 and c-MYC translocation genes, while three had translocation of the BCL6 and c-MYC genes. Despite appropriate therapy, the patient prognosis is poor. The median survival in these patients was 1.85 years. DLBCL with BCL2 and c-MYC rearrangement of the subgroups of lymphoma is associated with very poor survival. The presence of these two translocations has an aggressive clinical course.

Expressed IgH μ and τ transcripts share diversity segment in ranched Thunnus orientalis

It is now appreciated that in addition to the immunoglobulin (Ig)M and D isotypes fish also make the mucosal IgT. In this study we sequenced the full length of Ig τ as well as μ in the commercially important Thunnus orientalis (Pacific bluefin tuna), the first molecular analysis of these two Ig isotypes in a member of the order Perciformes. Tuna IgM and IgT are each composed of four constant (CH) domains. We cloned and sequenced 48 different variable (VH) domain gene rearrangements of tuna immunoglobulins and grouped the VH gene sequences to four VH gene segment families based on 70% nucleotide identity. Three VH gene families were used by both IgM and IgT but one group was only found to be used by IgM. Most interestingly, both μ and τ clones appear to use the same diversity (DH) segment, unlike what has been described in other species, although they have dedicated IgT and IgM joining (JH) gene segments. We complemented this repertoire study with phylogenetic and tissue expression analysis. In addition to supporting the development of humoral vaccines in this important aquaculture species, these data suggest that the DH-JH recombination rather than the VH-DH recombination may be instructive for IgT versus IgM/D bearing lymphocyte lineages in some fish.

Germinal center dysregulation by histone methyltransferase EZH2 promotes lymphomagenesis

Protection against deadly pathogens requires the production of high-affinity antibodies by B cells, which are generated in germinal centers (GCs). Alteration of the GC developmental program is common in many B cell malignancies. Identification of regulators of the GC response is crucial to develop targeted therapies for GC B cell dysfunctions, including lymphomas. The histone H3 lysine 27 methyltransferase enhancer of zeste homolog 2 (EZH2) is highly expressed in GC B cells and is often constitutively activated in GC-derived non-Hodgkin lymphomas (NHLs). The function of EZH2 in GC B cells remains largely unknown. Herein, we show that Ezh2 inactivation in mouse GC B cells caused profound impairment of GC responses, memory B cell formation, and humoral immunity. EZH2 protected GC B cells against activation-induced cytidine deaminase (AID) mutagenesis, facilitated cell cycle progression, and silenced plasma cell determinant and tumor suppressor B-lymphocyte-induced maturation protein 1 (BLIMP1). EZH2 inhibition in NHL cells induced BLIMP1, which impaired tumor growth. In conclusion, EZH2 sustains AID function and prevents terminal differentiation of GC B cells, which allows antibody diversification and affinity maturation. Dysregulation of the GC reaction by constitutively active EZH2 facilitates lymphomagenesis and identifies EZH2 as a possible therapeutic target in NHL and other GC-derived B cell diseases.

Immunoglobulin heavy chain gene rearrangement in oral B cell lymphomas

OBJECTIVE

Oral non-Hodgkin lymphomas (NHLs) are an extensive group of malignant lymphoid cell neoplasms that are the second most common group of oral cancers. Subtyping NHL is important to plan for appropriate treatment, and the analysis of clonality is in many instances used for helping in the diagnosis of NHL. Thus, the aim of this study was to analyze immunoglobulin heavy chain (IgH) gene rearrangement in a series of oral B cell lymphomas to investigate the sensitivity of seminested polymerase chain reaction (snPCR).

STUDY DESIGN

Paraffin embedded tissue samples from 16 cases of oral B cell lymphomas were retrieved and subjected to snPCR to investigate the IgH gene rearrangement.

RESULTS

The results showed monoclonal IgH rearrangement in 85.7% of the cases studied, as represented by finding one band within the expected range of amplification.

CONCLUSIONS

This study found that snPCR is a consistent method for the detection of gene rearrangement in paraffin-embedded tissue.

Localized DNA demethylation at recombination intermediates during immunoglobulin heavy chain gene assembly

The dynamics of DNA methylation during the complex genomic rearrangement of antigen receptor genes in developing B lymphocytes reveal localized demethylation of the first recombination product that may serve as a mark necessary for the second step of rearrangement.

Multiple epigenetic marks have been proposed to contribute to the regulation of antigen receptor gene assembly via V(D)J recombination. Here we provide a comprehensive view of DNA methylation at the immunoglobulin heavy chain (IgH) gene locus prior to and during V(D)J recombination. DNA methylation did not correlate with the histone modification state on unrearranged alleles, indicating that these epigenetic marks were regulated independently. Instead, pockets of tissue-specific demethylation were restricted to DNase I hypersensitive sites within this locus. Though unrearranged diversity (D_H) and joining (J_H) gene segments were methylated, DJ_H junctions created after the first recombination step were largely demethylated in pro-, pre-, and mature B cells. Junctional demethylation was highly localized, B-lineage-specific, and required an intact tissue-specific enhancer, Eμ. We propose that demethylation occurs after the first recombination step and may mark the junction for secondary recombination.

DNA methylation at CpG dinucleotides is implicated in the regulation of gene expression in mammals. However, the regulation of DNA methylation itself is less clear despite recent advances in identifying enzymes that add or remove methyl groups. We have investigated the dynamics of DNA methylation during genome rearrangements that assemble antigen receptor genes in developing B lymphocytes to determine whether methylation status correlates with rearrangement potential. Two recombination events generate immunoglobulin heavy chain (IgH) genes. The first step brings together diversity (D_H) and joining (J_H) gene segments to produce DJ_H junctions. We show that both gene segments are methylated prior to rearrangement, whereas the DJ_H product is demethylated. DJ_H junctional demethylation is tissue-specific and requires an enhancer, Eμ, located within the IgH locus. The latter observations indicate that localized demethylation of the DJ_H junction occurs after the first recombination step and thus does not guide this first step of IgH gene assembly. Our working hypothesis is that recombination induces demethylation of recombinant product and may mark the junction for the second step of IgH rearrangement, juxtaposition of variable (V_H) gene segments to rearranged DJ_H products to produce fully recombined V(D)J alleles.

Detection of clonal immunoglobulin heavy chain gene rearrangements by the polymerase chain reaction and capillary gel electrophoresis

Although well-established diagnostic criteria exist for mature B-cell neoplasms, a definitive diagnosis of a B-cell lymphoproliferative disorder cannot always be obtained using more conventional techniques such as flow cytometric immunophenotyping, conventional cytogenetics, fluorescence in situ hybridization, or immunohistochemistry. However, because B-cell malignancies contain identically rearranged immunoglobulin heavy chain genes, the polymerase chain reaction (PCR) can be a fast, convenient, and dependable option to identify clonal B-cell processes. This chapter describes the use of PCR and capillary electrophoresis to identify clonal immunoglobulin heavy chain (IGH) variable and joining region (VH-JH) gene rearrangements (IGH VH-JH PCR) using a commercially available method employing multiple multiplex PCR tubes that was originally developed as the result of a large European BIOMED-2 collaborative study (Invivoscribe Technologies). The core protocol involves the use of three separate master mix tubes that target the conserved framework (FR1, FR2, and FR3) and joining (J) regions of the IGH gene. Analysis of these three framework regions can detect approximately 88% of clonal IGH gene rearrangements.

Antibody repertoire development in fetal and neonatal piglets. XXII. λ Rearrangement precedes κ rearrangement during B-cell lymphogenesis in swine

VDJ and VJ rearrangements, expression of RAG-1, Tdt and VpreB, and the presence of signal joint circles (SJC) were used to identify sites of B-cell lymphogenesis. VDJ, VλJλ but not VκJκ rearrangements or SJC were recovered from yolk sac (YS) at 20 days of gestation (DG) along with strong expression of VpreB and RAG-1 but weak Tdt expression. VλJλ rearrangements but not VκJκ rearrangements were recovered from fetal liver at 30-50 DG. SJC were pronounced in bone marrow at 95 DG where VκJκ rearrangements were first recovered. The VλJλ rearrangements recovered at 20-50 DG used some of the same Vλ and Jλ segments seen in older fetuses and adult animals. Hence the textbook paradigm for the order of light-chain rearrangement does not apply to swine. Consistent with weak Tdt expression in early sites of lymphogenesis, N-region additions in VDJ rearrangements were more frequent at 95 DG. Junctional diversity in VλJλ rearrangement was limited at all stages of development. There was little evidence for B-cell lymphogenesis in the ileal Peyer's patches. The widespread recovery of VpreB transcripts in whole, non-lymphoid tissue was unexpected as was its recovery from bone marrow and peripheral blood monocytes. Based on recovery of SJC, B-cell lymphogenesis continues for at least 5 weeks postpartum.

Detection of Epstein-Barr virus DNA and expression of CD30 antigen in primary anaplastic diffuse large B-cell lymphoma of the brain

We describe a case of primary anaplastic diffuse large-cell lymphoma arising in the central nervous system (CNS). Primary CD30-positive anaplastic diffuse large B-cell lymphoma of the brain is very rarely reported. Given that this tumor is immunohistochemically heterogeneous, polymerase chain reaction (PCR) and Epstein-Barr virus (EBV) analysis of tumor DNA are essential techniques for early and accurate histological diagnosis in these CD30-positive cerebral lymphoma cases. We report an early CD30- and EBV-positive anaplastic diffuse large B-cell lymphoma in the CNS that was diagnosed not only from the immunohistochemical study and MRI findings, but also from the genotype confirmations. This tumor was documented to have EBV episomes of monoclonal origin by PCR analysis of immunoglobulin gene rearrangement.

[Overrepresentation of specific gene segments of expressed immunoglobulin heavy chain variable region among unmutated and mutated patients with chronic lymphocytic leukemia]

OBJECTIVE

To investigate the overrepresentation of specific gene segments of immunoglobulin heavy chain variable region (IgVH) among unmutated and mutated chronic lymphocytic leukemia (CLL) patients and its prognostic implication.

METHODS

Multiplex PCR was used to identify the expression of IgVH segment and its mutation status in CLL.

RESULTS

Analyses were successfully performed in 80 of 85 samples. Marked skewed IgVH families were disclosed. The most commonly used VH was VH3 (40.0%), followed by VH4 (30.0%), VHI (13.8%), VH2 (10.0%) and VH5, VH7 (2.5%). Fifty-six patients (70.0%) had mutated VH, 24 (30.0%) unmutated VH. Nine cases (11.3%) were with 100% germline sequence. Fifteen cases (15/24, 62.5%) in VH4, 29 (29/32, 90.7%) in VH3, and 4 (4/11, 36.3%) in VH1 had mutated VH. The most frequently used IgVH gene was VH4-39 (13.8%), and VH4-34 (8.8%). J4 (36/66, 54.5%) and D3 (25/66, 37.8%) were the most frequently used in J and D genes. The progression-free survival (PFS) was 82 and 17 months (P = 0.000), and the overall survival (OS) was 90 and 41 months (P = 0.009), respectively, for mutated and unmutated cases. Recurrent CDR3 sequences were found in our patients and 2 patients with VH1-69 had CDR3 sequences highly similar to those reported in literature.

CONCLUSION

There is difference in IgVH gene segment usage and mutational status in different area CLL patients. Recurrent CDR3 sequences were found in specific IgVH gene segments, which highlights the importance of immunoglobulin mediated stimulation in the development of CLL.

[Pulmonary lymphomatoid granulomatosis: an immunohistochemical and gene rearrangement study]

OBJECTIVE

To study the immunophenotype and gene rearrangement pattern of pulmonary lymphomatoid granulomatosis.

METHODS

Nine cases of pulmonary lymphomatoid granulomatosis, included 5 cases of open lung biopsy, 3 cases of lobectomy specimen and 1 case of autopsy, were retrospectively analyzed by immunohistochemistry, in-situ hybridization for Epstein-Barr virus-encoded RNA, immunoglobulin and T-cell receptor gene rearrangement studies.

RESULTS

The age of patients ranged from 3 to 59 years. The male-to-female ratio was 3: 6. Histologically, all cases showed lymphocytic infiltration surrounding the blood vessels and in the perivascular areas. Most of these lymphoid cells expressed T-cell marker CD3. There were also variable numbers of CD20-positive B cells. The staining for CD56 was negative. According to the WHO classification, there were 4 cases of grade I , 1 case of grade II and 4 cases of grade III lesions. Six cases had gene rearrangement studies performed and 3 of them demonstrated clonal immunoglobulin gene rearrangement (including 1 of the grade II and 2 of the grade III lesions). No T-cell receptor gene rearrangement was detected.

CONCLUSIONS

Pulmonary lymphomatoid granulomatosis may represent a heterogeneous group of lymphoproliferative disorders. Some of the cases show B-cell immunophenotype and clonal immunoglobulin gene rearrangement, especially the grade II and grade lesions. They are likely of lymphomatous nature.

[Molecular genetic features of sporadic Burkitt's lymphoma in children]

OBJECTIVE

To investigate the molecular genetic features and diagnostic aspects of sporadic Burkitt's lymphoma (BL) in children.

METHODS

Tissue microarray was constructed to include 64 cases of pediatric BL and 6 cases of pediatric diffuse large B-cell lymphoma (DLBCL). Immunohistochemistry and fluorescence in-situ hybridization for c-myc, bcl-2, bcl-6, IgH, myc/IgH and bcl-2/IgH gene were performed. Cases of pediatric Burkitt's lymphomas were subclassified into three groups based on their cellular orgins: the germinal center (GC) group, the late-germinal center (late-GC) group and the post-germinal center (post-GC) group.

RESULTS

Among 64 Burkitt's lymphomas studied, expression of CD20, CD10, bcl-6, bcl-2 and MUM1 by immunohistochemistry were 100% (64 cases), 98.4% (63 cases), 96.9% (62 cases), 0 (0 cases) and 23.4% (15 cases), respectively. Various gene rearrangements were found involving the c-myc 93.1% (54/58 cases) and IgH 82.8% (48/58 cases). Detailed rearrangements are as follows: 46 cases (85.2%) myc/IgH gene translocation along with c-myc and IgH gene rearrangement; 4 cases (7.4%) c-myc gene rearrangement without IgH and myc/IgH abnormality; 4 cases (7.4%) without c-myc, IgH or myc/IgH gene rearrangement. No case showed bcl-2 gene abnormality (100%). Fifty nine cases showed normal bcl-6 gene status. One case had bcl-6 gene rearrangement and amplification with the pathologic and immunophenotypic characteristics of BL, leading to a revised pathological diagnosis of B-cell lymphoma, unclassifiable with features intermediate between diffuse large B-cell lymphoma and Burkitt's lymphoma (DLBCL/BL). Two cases showed c-myc gene rearrangement. Two cases showed bcl-6 gene amplification and 6 DLBCL cases had a normal status of bcl-2/IgH.

CONCLUSIONS

A majority of pediatric sporadic BL arise from the germinal center B cells, most of which have c-myc gene rearrangement. It is useful to distinguish BL and DLBCL by multiple genes detection.

Serum immunoglobulin free light chain measurements and heavy chain isotype usage provide insight into disease biology in patients with POEMS syndrome

POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes) syndrome is a rare paraneoplastic syndrome in which nearly all patients have a monoclonal lambda restricted plasma cell disorder. We investigated whether patients with POEMS have abnormal serum immunoglobulin free light chain (FLC) ratios. Fifty patients with newly diagnosed POEMS syndrome were assessed. Cystatin C levels were measured to discern whether subclinical renal insufficiency could account for FLC elevations in the presence of a normal FLC ratio. Forty-five patients (90%) had elevated lambda FLC; however, only nine (18%) had abnormal FLC ratios. The rise in serum FLC of POEMS patients appeared to be multifactorial-both a function of subclinical renal insufficiency and polyclonal activation of medullary and extramedullary plasma cells. Those patients expressing a clonal IgA were more likely to have clonal plasmacytosis observed on iliac crest biopsy than those with IgG. In summary, serum immunoglobulin profiles are unique in POEMS syndrome as compared with other plasma cell disorders.

[Immunoglobulin heavy chain gene rearrangement study in difficult cases of B-cell lymphoproliferative disorder]

OBJECTIVE

To evaluate the ancillary diagnostic value of IgH gene rearrangements in those B-cell lymphoproliferative disorder cases whom are difficult in making a final diagnosis.

METHODS

IgH gene clonal rearrangements were retrospectively analyzed in a total of 77 diagnostically difficult B-cell lympho-proliferative patients. Standardized BIOMED-2 system IgH gene clonality assay kit targeting FR1, FR2, FR3 was used, followed by heteroduplex-polyacrylamide gel electrophoresis (PAGE) and silver nitrate staining.

RESULTS

The final diagnoses of the 77 cases were: 12 cases of reactive lymphoid hyperplasia, 20 cases of atypical lymphoid hyperplasia or suspicious lymphoma, and 45 cases of B-cell lymphoma. Detection rates of at least one positive reaction were 2/12, 11/20 (55%), 36/45 (80%) in the three groups, respectively. In B-cell lymphomas, the clonality detection rate of FR1, FR2 and FR3 was 60% (27/45), 60% (27/45) and 56% (25/45), respectively. The type distribution were: 20 marginal zone lymphomas, including 18 extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue, 7 diffuse large B-cell lymphomas, 7 follicular lymphomas, 1 mantle-cell lymphoma, 1 Burkitt's lymphoma, 4 plasma cell neoplasms and 5 unclassified B-cell lymphomas. Rearrangements of FR1, FR2 or FR3 were not detected in 9 (20%) of the B cell lymphoma cases, nevertheless, one of them had developed liver lesion later, and was confirmed finally to be B cell lymphoma. Fourteen patients of reactive lymphoid hyperplasia with positive IgH gene clonal rearrangements, and atypical lymphoid hyperplasia had follow-up history available. Four of them were diagnosed as lymphoid malignancies upon further biopsy, and in three of them, clonal IgH gene rearrangements were detected.

CONCLUSIONS

B-cell lymphoproliferative disorder requiring a detection of clonal IgH gene rearrangement for making a final diagnosis. Combined detections of three IgH FR1, FR2 and FR3 rearrangements provide important ancillary diagnostic value in confirming suspected B-cell lympho-proliferative disorders. It is important to take an additional biopsy or to follow-up those patients who that have a detectable IgH gene clonal rearrangement but without apparent morphological evidence of lymphoma. For cases with a negative IgH gene rearrangements, it might be necessary to perform clonality analysis for other forms of gene rearrangements including IgH or IgK and IgL in order to further improve the detection sensitivity.

[Solitary plasmacytoma of bone: a clinicopathologic, immunohistochemical and immunoglobulin gene rearrangement study]

OBJECTIVE

To investigate clinicopathologic features of solitary plasmacytoma of bone (SPB) and the role of immuno-phenotype and immunoglobulin gene rearrangement detection in the diagnosis and differential diagnosis of SPB.

METHODS

A total of 21 cases of SPB were selected during a period from 1990 to 2008. A retrospective clinicopathologic study and immunohistochemistry (EnVision or EliVision methods) of 17 antigens were performed. In addition, universal IgH (FR3A/LJH/VLJH) primers and BIOMED-2 PCR multiplex tubes were used for IgK and IgL rearrangement analysis.

RESULTS

The age of patients ranged from 36 to 72 years with a media of 50 years. Axial skeleton was the most common site of involvement, accounting for 66.7% of the cases (14 of 21), followed by the extremities of 33.3% (7 cases). Low serum level of M-components was found in 5 cases, including two of IgG type (21.4 g/L) and three of IgA type. Clinical manifestations were closely related to the anatomic sites involved, such as pain due to bone destruction, symptoms and signs caused by compression of spinal cord or nerve root, and pathological fracture. All cases presented as a solitary osteolytic lesion. According to the histological grading criteria, grade I tumor was seen in 12 of 21 cases (57.1%). The remaining were grade II (5 cases, 23.8%) and grade III (4 cases, 19.0%). Immunohistochemically, the neoplastic cells expressed two or more plasma cell antigens, including CD138, CD38 and PC, but no CD19 and CD20. CD79a expression detected in 23.8%(5/21) of the cases. Expression of CD56, CD27 and CD44v6 were 57.1% (12/21), 15.0% (3/20) and 23.8% (5/21), respectively. Follow-up data were available in 12 of the 21 patients (57.1%). Five patients were alive and 7 died. Three patients developed multiple myeloma (MM) and died of the tumor.

CONCLUSIONS

SPB is a rare tumor with bone pain as the most common presenting symptom due to bone destruction. The diagnosis of EMP can only be established after exclusion of an extramedullay invasion by MM. Immunophenotype and IgH gene rearrangement analysis play important roles in the diagnosis of SPB.

[Application of BIOMED-2 primers in immunoglobulin gene rearrangement analysis of ocular adnexal lymphoma: a pilot study]

OBJECTIVE

To assess the practical value of BIOMED-2 primers in the diagnosis of ocular adnexal lymphoma by PCR.

METHODS

DNA was extracted from 63 formalin-fixed paraffin-embedded (FFPE) ocular adnexal lymphoma specimens. The DNA quality was evaluated by PCR-based amplification of housekeeping gene beta-actin. IgH(B) and IgK(B) primers of BIOMED-2 standardized clonality analysis system were used to evaluate the immunoglobin gene rearrangements. PCR products were analyzed using capillary electrophoresis and GeneScan software.

RESULTS

76.2% (48/63) of FFPE samples produced amplifiable DNA for detection of Ig gene rearrangements.Positive detection rates by BIOMED-2 IgH(B) and IgK(B) primers were 79.2% (38/48) and 68.8% (33/48), respectively, with a combined positive detection rate of 91.7% (44/48).

CONCLUSIONS

IgH(B) and IgK(B) primers of BIOMED-2 are suitable for the detection of clonal rearrangements of Ig gene using FFPE specimens of ocular adnexal lymphomas.

Efficacy of rituximab monotherapy for an elderly hemodialysis patient with primary cardiac lymphoma

We report a case of primary cardiac lymphoma (PCL) occurring in a 76-year-old man during maintenance hemodialysis. Chest computed tomography (CT) revealed a tumor with pericardial effusion in the left ventricular posterior wall. Cytological examination of the pericardial fluid revealed monotonous lymphoid cells positive for B-cell markers, and clonal immunoglobulin heavy chain gene rearrangement was detected, indicating B-cell lymphoma. Rituximab monotherapy was administered biweekly at the therapeutic level on hemodialysis. The follow-up chest CT showed tumor disappearance with pericardial fluid after two courses of therapy. Rituximab monotherapy was effective for an elderly hemodialysis patient with PCL.

VH3-21 Gene Usage in Chronic Lymphocytic Leukemia – Characterization of a New Subgroup with Distinct Molecular Features and Poor Survival

During recent years it has become evident that lymphoproliferative diseases of B-cell origin display preferential immunoglobulin (Ig) variable heavy chain (V(H)) gene usage. For instance, the V(H)1-69 and V(H)4-34 genes were early found to be overexpressed in B-cell chronic lymphocytic leukemia (CLL) and other B-cell lymphomas. The implications of biased V(H) gene usage have been speculated to be a result of stimulation of unknown antigens, which gives increased proliferation of B-cells with certain V(H) gene configuration and consequently higher probability to undergo transformation. Thus, V(H) gene usage may play a role in development of leukemias and lymphomas. Recently, we could confirm the over usage of the V(H)1-69 and V(H)4-34 genes in CLL, but a novel finding was that the V(H)3-21 gene was preferentially utilized in CLL patients with mutated V(H) genes. These V(H)3-21+ Ig rearrangements showed molecular peculiarities such as shorter lengths of the third complementarity determining region (CDR) and had similar amino acid composition of their CDR3s, implicating recognition of the same antigen in individual tumors. Most of the V(H)3-21+ patients also showed a predominance of lambda chain expression and biased usage of 1 specific V(lambda) gene, V2-14. Furthermore, overall survival appeared to correlate with V(H)3-21 usage and, regardless of V(H) gene mutation status, V(H)3-21+ patients had a poor outcome. All in all, it appears that V(H)3-21 gene usage define a new entity of CLL. The remaining question now to be clarified is if antigen(s) actually are involved in the pathogenesis of V(H)3-21+ CLL.

Evaluation of B-cell clonality in archival skin biopsy samples of cutaneous B-cell lymphoma by immunoglobulin heavy chain gene polymerase chain reaction

Polymerase chain reaction (PCR)-based detection of clonal T- and B-cells is widely used in the diagnosis of various lymphomas, including those of the skin. A large number of corresponding methods have been published. Recently, for the first time, standardized PCR protocols were developed in common by 14 European centers of lymphoma diagnosis and research (Biomed-2 protocols). Here, we have applied Biomed-2 immunoglobulin heavy chain (IgH)-PCR for clonality detection in primary cutaneous B-cell lymphoma (CBCL) and compared it with previously established methods. The DNA of 43 paraffin-embedded lesional skin biopsies of confirmed CBCL cases [27 follicle center cell lymphoma (FCCL), 11 marginal zone B-cell lymphoma/immunocytoma (MZL/IC) and five large CBCL of the lower leg (CBCL-LL)] were amplified by the Biomed-2 IgH-PCR protocols as well as using four other assays, priming also the three IgH framework regions (FR) 1-3. All PCR products were analysed by fluorescence fragment analysis. Twenty-nine of 43 (67%) CBCL samples (5/5, 100% of CBCL-LL; six of 11, 54.5% of IC/MZL; 18 of 27, 66.7% of FCCL) showed monoclonal B-cell presence complementary in all of the IgH-PCR. The three Biomed-2 PCR indicated together clonality in 24 of 43 samples (56%). Considering each method separately, the Biomed-2 FR3-PCR showed the highest rate of clonality detection (20 of 43, 47%). In conclusion, the Biomed-2 FR3-PCR is recommended for detecting B-cell clonality in archival skin samples of CBCL but should be completed by FR1- and/or FR2-PCR.

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.

Antisense transcripts of V(D)J rearrangements; artifacts caused by false priming?

Somatic hypermutation (SH) of V(D)J rearrangements at the IGH and IGL loci diversifies the IG repertoire during the germinal center response. SH is absolutely dependent on the enzyme activation induced cytidine deaminase (AID) that initiates the SH process by deaminating C nucleotides in ssDNA. Mutations from G and C are thought to occur as a result of strand symmetrical deamination of C by AID on the coding and non-coding strands respectively. Mutations from A and T are introduced in a strand biased way during error prone repair of the AID induced lesion. SH is linked to transcription and it has been proposed that bidirectional transcription across V(D)J rearrangements occurs in activated and quiescent B cells and that it is co-opted to facilitate the accessibility of the two DNA strands by regulating accessibility of single stranded DNA to AID. We have developed a quantitative method to study directional transcription. Our method controls for differences in efficiency and specificity of reverse transcription that are known to be able to generate false positive data. This method does not detect antisense transcripts in exonic or intronic regions within the hypermutation domain of the spontaneously hypermutating cell line Ramos, or in human blood B cells or tonsil cells, providing convincing evidence that antisense transcripts are rare or absent in human B cells.

[Clinical significance in detection of immunoglobulin heavy chain clonal rearrangement in bone marrow of patients with B cell lymphoma]

OBJECTIVE

To explore the feasibility of semi-nested PCR technique for detection of immunoglobulin heavy chain (IgH) clonal rearrangement in bone marrow of B-cell lymphoma patient and to further evaluate its clinicopathological value.

METHODS

Gene clonal rearrangement of IgH was detected by semi-nested PCR using primers of FR2 & FR3A in 105 bone marrow samples of patients with B-cell lymphoma. The PCR detection results were compared with the cytomorphology of bone marrow aspiration biopsy. The correlation between PCR detection results and clinicopathological factors were evaluated.

RESULTS

Among 105 cases of B-cell lymphoma, bone marrow involvement was detected by PCR technique in 48 cases (45.7%), while only 22 cases (21.0%) were detected by bone marrow cytological analysis. There was a significant difference between two methods (P < 0.05), and the concordance rate was 71.4%. The incidence of bone marrow involvement at the time of initial diagnosis detected by PCR technique was 30.8% for diffuse large B cell lymphoma (DLBCL), 25.0% for follicular lymphoma (FL), and 100.0% for small lymphocytic lymphoma (SLL), respectively. Bone marrow involvement detected by PCR detection correlated with Ann Arbor stage. Rate of clonal IgH gene rearrangement by PCR in early B-cell lymphoma was lower than that in advanced stage B-cell lymphoma patients (P = 0.02). There was no statistically significant difference in efficacy between patients with positive and negative results detected by PCR (P > 0.05). But difference in complete response (CR) rate (23.3% and 46.3%) had significant difference (P = 0.019).

CONCLUSION

Semi-nested PCR analysis may be an effective method for detection of abnormalities in bone marrow in patients with B-cell lymphoma and is superior to cytomorphology. The positive rate in patients with advanced Ann Arbor stage is higher than that in patients with early Ann Arbor stage, and patients with PCR negative result have more chances to achieved CR after treatment.

[Methotrexate-associated lymphoproliferative disorder presenting as oral ulcers in a patient with rheumatoid arthritis]

Methotrexate-associated lymphoproliferative disorders are a heterogeneous group of lymphoid proliferations or lymphomas that develop in patients with autoimmune diseases treated using methotrexate. These lymphoproliferative disorders are often associated with Epstein-Barr virus infection and occasionally regress after the withdrawal of methotrexate therapy. The lymphoproliferative disorder in this case was diffuse large B-cell lymphoma, unusually presenting as oral ulcers in a 79-year-old woman on treatment with methotrexate for longstanding rheumatoid arthritis. Latent membrane protein 1 positivity was detected by immunohistochemistry and Epstein-Barr-virus encoded small RNA positivity by chromogenic in situ hybridization. Clonality was confirmed by immunohistochemistry (kappa light-chain restriction), polymerase chain reaction (monoclonal immunoglobulin H gene rearrangement), and capillary electrophoresis (GeneScan). Staging procedures were negative. Withdrawal of methotrexate therapy led to complete remission within 6 weeks, and the patient is alive and disease-free 18 months after the diagnosis was made. The oral cavity is not often involved in the initial presentation of methotrexate-associated lymphoproliferative disorders, and presentation with intraoral ulcers is very rare. We have performed a review of the literature on methotrexate-associated lymphoproliferative disorders presenting as ulcers in the oral cavity.

B-cell clones as early markers for chronic lymphocytic leukemia

BACKGROUND

Otherwise healthy persons with a small number of B-cell clones circulating in the peripheral blood have been designated as having monoclonal B-cell lymphocytosis (MBL). Hospital-based series indicate an excess risk of progression from MBL to chronic lymphocytic leukemia (CLL). In this prospective cohort study, we tested the hypothesis that CLL is always preceded by MBL.

METHODS

Among 77,469 healthy adults who were enrolled in the nationwide, population-based Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, we identified 45 subjects in whom CLL was subsequently diagnosed (up to 6.4 years later) through the collection of a peripheral-blood sample. Using six-color flow cytometry (with antibodies CD45, CD19, CD5, CD10, kappa, and lambda) and immunoglobulin heavy-chain gene rearrangement by reverse-transcriptase-polymerase-chain-reaction assay, we determined the association between MBL and subsequent CLL and characterized the immunoglobulin gene repertoire of the prediagnostic B-cell clones.

RESULTS

On the basis of either flow-cytometric or molecular analysis, 44 of 45 patients with CLL (98%; 95% confidence interval [CI], 88 to 100) had a prediagnostic B-cell clone; in 41 patients (91%; 95% CI, 79 to 98), the presence of the B-cell clone was confirmed by both methods. The presence of immunoglobulin heavy-chain variable (IGHV) genes was determined in 35 of 45 prediagnostic clones (78%). Of these clones, 16 (46%) were IGHV3 subgroup genes (including 6 [17%] IGHV3-23 genes) and 9 (26%) were IGHV4 subgroup genes (including 4 [11%] IGHV4-34 genes). Furthermore, 27 of 35 of the IGHV sequences (77%) had mutations, with similar distributions after stratification either below or above the median time between the collection of the prediagnostic blood sample and the subsequent CLL diagnosis.

CONCLUSIONS

In peripheral blood obtained up to 77 months before a CLL diagnosis, prediagnostic B-cell clones were present in 44 of 45 patients with CLL.

I. VH gene transcription creates stabilized secondary structures for coordinated mutagenesis during somatic hypermutation

During the adaptive immune response, antigen challenge triggers a million-fold increase in mutation rates in the variable-region antibody genes. The frequency of mutation is causally and directly linked to transcription, which provides ssDNA and drives supercoiling that stabilizes secondary structures containing unpaired, intrinsically mutable bases. Simulation analysis of transcription in VH5 reveals a dominant 65nt secondary structure in the non-transcribed strand containing six sites of mutable ssDNA that have also been identified independently in human B cell lines and in primary mouse B cells. This dominant structure inter-converts briefly with less stable structures and is formed repeatedly during transcription, due to periodic pauses and backtracking. In effect, this creates a stable yet dynamic "mutability platform" consisting of ever-changing patterns of unpaired bases that are simultaneously exposed and therefore able to coordinate mutagenesis. Such a complex of secondary structures may be the source of ssDNA for enzyme-based diversification, which ultimately results in high affinity antibodies.

Distinctive IgVH gene segments usage and mutation status in Chinese patients with chronic lymphocytic leukemia

BACKGROUND AND OBJECTIVES

The incidence of chronic lymphocytic leukemia (CLL) in Asian countries is lower than that in the Western ones, where CLL is the most common leukemia. It is a clinically heterogeneous disease, with survival ranging from a few months to decades. The mutation status of the immunoglobulin variable heavy chain (IgVH) gene has significantly improved prediction of the risk for disease progression. We investigated the frequency and mutation status of IgVH gene expression in Chinese patients with CLL.

METHODS

IgVH gene segments usage and mutation status were investigated by multiplex RT-PCR, and the relationship between IgVH somatic mutation status and the expression of CD38 and ZAP-70 was analyzed in 65 CLL patients.

RESULTS

Forty-five (69.2%) patients had mutated IgVH, and 20 (30.8%) had unmutated IgVH. The most frequently expressed VH gene family was found to be VH3 (47.7%) followed by VH4 (40%), VH1 (6.2%), VH2 (4.6%) and VH7 (1.5%), with no expression of VH5 or VH6 gene families. VH1-69 and VH3-21 which commonly overused in Western CLL were very low in our cohort. IgVH gene mutation status was significantly associated with the expression of CD38.

CONCLUSIONS

The frequency of IgVH gene families indicates significant difference in Chinese CLL patients compared with Western patients, suggesting involvement of ethnic and/or environmental factors in CLL disease initiation. The expression of them may be simple and reliable surrogates for the identification of IgVH mutations.

Detection of clonality in lymphoproliferations using PCR of the antigen receptor genes: Does size matter?

A biopsy of a nasal mass that had morphologic and immunostaining features consistent with a B-cell lymphoma was studied for clonality using PCR of the IgH gene. An unexpectedly low molecular weight DNA fragment of approximately 140bp (acceptable size limit: 250-295bp) was obtained using FR2 and JH primers. The sequence of this DNA was consistent with a clonal IgH rearrangement followed by a deletion that removed most of the downstream portion of the V segment. Thus, the biopsy contained a monoclonal population of B-lymphocytes, consistent with a diagnosis of lymphoma. This work illustrates that bands outside of the size range expected from PCR of the antigen receptor genes may still be consistent with a monoclonal result.

PCR analysis of immunoglobulin heavy chain and TCR gene rearrangements in diagnosis of lymphoproliferative disorders on formalin-fixed, paraffin-embedded tissues

To confirm a diagnosis of malignant lymphomas it is imperative to distinguish between reactive and neoplastic proliferation. The PCR (polymerase chain reaction) is a method that can be used for detection of clonal rearrangements of the immunoglobulin heavy chain (IgH) and T-cell receptor (TCR) genes. This study summarizes the outcomes of PCR analysis of IgH and TCR gene rearrangements in 91 bioptic cases of lymphoproliferative disorders. In the class of B lymphomas we detected clonal IgH rearrangement in nearly 83% of cases and in class of T lymphomas in 81% of cases. We can affirm that PCR analysis of B and T cell clonality on DNA extracted from the whole section of formalin-fixed, paraffin-embedded tissue is very suitable for routinely elaborate this. Its influence on the diagnostics of morphological unclear cases in particular, is crucial and is useful in establishing a diagnosis of lymphoid neoplasias in specimens in which histological and immunophenotypic studies are inconclusive.

Molecular characteristics and prognostic significance of Bcl-2/IgH gene rearrangement in Serbian follicular lymphoma patients

Follicular lymphoma (FL) is characterized by the presence of a t(14;18) chromosomal translocation that results in overexpression of bcl-2 protein. Bcl-2/IgH gene rearrangement is detected in 80-90% of follicular lymphomas in Western countries. The aim of this study was to analyze the bcl-2/IgH rearrangement in FL lymphoma patients in Serbia, by PCR technique, correlate molecular findings with clinical characteristics and outcome and assess the prognostic significance of these rearrangements. One hundred-seven patients (median age, 54 years; male/female ratio:60/47) diagnosed with FL were included in the study. DNA samples were obtained from paraffin embedded lymphoid tissue of patients. Bcl-2/IgH rearrangement was assessed for the major breakpoint region (MBR), 5' MBR and the minor cluster region (mcr) breakpoints by PCR technique. We detected a t(14;18) in 81.3% (87/107) of patients. The distribution of bcl-2-IgH rearrangement was as follows: 88,5% (77/87) in MBR breakpoint, 10,35% (9/87) in 5' MBR, whereas mcr bcl-2-IgH rearrangement was observed in one patient (1.15%). No rearrangements were detected in remaining 20 patients (18.7%). This is the first analyses of the frequency of the bcl-2/IgH gene rearrangement in Serbian FL patients, as well as in Eastern European countries. There was no correlation between presence of bcl-2/IgH gene rearrangement and clinical outcome of disease. Incidence of bcl-2/IgH gene rearrangement in Serbian FL patients is relatively high, and similar to frequency in Western countries. Presence of this rearrangement in tumor tissue is not of prognostic significance.

Diagnostic and prognostic utility of t(14;18) in follicular lymphoma

BACKGROUND

Follicular lymphoma (FL) is one of the most common non-Hodgkin's lymphomas of B cells, being closely associated with a t(14;18) translocation. Detection of t(14;18), which is present in 70-95% of FL, might aid in FL diagnosis.

OBJECTIVE

To compare the efficacy of routine polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) techniques in detecting t(14;18) in paraffin-embedded tissue samples of FL patients at different stages. Combined with other immunophenotypic biological determinants, detection of t(14;18) might help to determine patients at increased risk according to the FL International Prognostic Index (FLIPI) and therefore facilitate appropriate treatment.

DESIGN AND METHODS

This study was mainly based on a retrospective examination of formalin-fixed, paraffin-embedded lymph nodes. We selected fixed tissue samples of 21 FL patients treated at the National Cancer Institute Center in the period from 2000 to 2001.

RESULTS

FISH techniques could detect 14 of 18 FL cases with a sensitivity of 77.8%, while the PCR technique could detect only 11 of 18 FL cases with a sensitivity of 61.1%, resulting in a statistically significant difference between both techniques (p = 0.004). According to the FLIPI index, 9 of the 18 FL patients were categorized into the high-risk group (50%), 5 in the intermediated-risk group (27.8%) and 4 in the low-risk group (22.2%).

CONCLUSION

The sensitivity of FISH is superior to that of PCR in the detection of the t(14;18) translocation in paraffin-embedded tissue samples. There is a statistically significant correlation between both CD10 and FISH with FLIPI.

[Monitoring IgH levels in patients with B-cell malignancy by real-time quantitative PCR after hematopoietic stem cell transplantation and its significance]

The study was purpose to evaluate the value of real time quantitative-PCR for monitoring IgH level in patients with B-cell malignancy after hematopoietic stem cell transplantation (HSCT). Quantification of IgH levels was performed on bone marrow mononuclear cells from 9 patients with B-cell malignancy before and after HSCT by PCR using the consensus JH TaqMan probe in combination with an allele-specific oligonucleotide (ASO) upstream primer. The IgH levels was normalized by control gene GAPDH. The results indicated that the reproducible sensitivity of RQ-PCR was 1 copy, the significant reduction of IgH copies was observed in bone marrow samples of 9 patients at one month post HSCT (6.67x10(3)/10(6) GAPDH vs 29/10(6) GAPDH, p<0.01). 3 out of 9 patients who achieved complete clinical and molecular cytogenetic remission (CCyR) contained persistently measurable low IgH level of 10(2)/10(6) GAPDH within 15 months and no detectable IgH at 18 months post HSCT. Whereas 5 out of 9 patients whose IgH copies were less than 10(2)/10(6) GAPDH within 3 months and less than 10(3)/10(6) GAPDH 3 months post HSCT achieved a sustained complete remission (CR). IgH copies in one patient were 4.5x10(3)/10(6) GAPDH at 3 months post HSCT, who relapsed at 4 months post HSCT. The median levels of tumor contamination in the stem cell harvests from 8 patients measured by RQ PCR were 3.68x10(2) (0-1720)/10(6) GAPDH. RQ PCR showed that PBPC harvests were less contaminated than BM harvests [75 (0-890)/10(6) GAPDH vs 1.1x10(3) (527-1720)/10(6) GAPDH, p<0.05]. 8 patients whose stem cell harvest were avaiable for RQ PCR were still in CR despite of the tumor contamination. The level of tumor contamination in stem cell harvest well correlated with IgH levels at diagnosis and one month after HSCT (r=0.810, r=0.708, p<0.05). It is concluded that RQ PCR can effectively monitor the IgH levels in patients with B-cell malignancy after auto-HSCT. 10(3)/10(6) GAPDH within 3 months post HSCT may be a cut-off level of IgH copies, which may be used to evaluate different prognoses of patients.

FcgammaRIIIA and FcgammaRIIA polymorphisms do not predict clinical outcome of follicular non-Hodgkin's lymphoma patients treated with sequential CHOP and rituximab

We analyzed FcgammaRIIIA-158V/F and FcgammaRIIA-131H/R polymorphisms in a cohort of 94 newly diagnosed follicular lymphoma (FL) patients sequentially treated with CHOP and Rituximab. With a median follow-up of 5.8 years, the overall survival at 8 years is 83%. Univariate and multivariate analysis showed no correlation between FcgammaRIIIA-158VV/VF and FcgammaRIIA-131HH/HR polymorphisms and the overall response rate, the molecular response and the event-free survival obtained after CHOP and Rituximab. By contrast, the achievement of a durable molecular clearance of BCL2/IgH+ cells detectable in the bone marrow is confirmed to be a reliable predictive factor of a better long-term clinical outcome.

Repeat organization and epigenetic regulation of the DH-Cmu domain of the immunoglobulin heavy-chain gene locus

The first steps of murine immunoglobulin heavy-chain (IgH) gene recombination take place within a chromosomal domain that contains diversity (D(H)) and joining (J(H)) gene segments, but not variable (V(H)) gene segments. Here we show that the chromatin state of this domain is markedly heterogeneous. Specifically, only 5'- and 3'-most D(H) gene segments carry active chromatin modifications, whereas intervening D(H)s are associated with heterochromatic marks that are maintained by ongoing histone deacetylation. The intervening D(H)s form part of a tandemly repeated sequence that expresses tissue-specific, antisense oriented transcripts. We propose that the intervening D(H) genes are actively suppressed by repeat-induced epigenetic silencing, which is reflected in their infrequent representation in DJ(H) junctions compared to the flanking D(H) genes.

Kinetic, affinity, and diversity limits of human polyclonal antibody responses against tetanus toxoid

Due to technical limitations, little knowledge exists on the composition of Ag-specific polyclonal Ab responses. Hence, we here present a molecular analysis of two representative human Ab repertoires isolated by using a novel single-cell cloning approach. The observed genetic diversity among tetanus toxoid-specific plasma cells indicate that human polyclonal repertoires are limited to the order of 100 B cell clones and hypermutated variants thereof. Affinity and kinetic binding constants are log-normally distributed, and median values are close to the proposed affinity ceilings for positive selection. Abs varied a million-fold in affinity but were restricted in their off-rates with an upper limit of 2 x 10(-3) s(-1). Identification of Abs of high affinity without hypermutations in combination with a modest effect of hypermutations on observed affinity increases indicate that Abs selected from the naive repertoire are not only of low affinity but cover a relatively large span in affinity, reaching into the subnanomolar range.

Immunoglobulin gene rearrangements and the pathogenesis of multiple myeloma

The ability to rearrange the germ-line DNA to generate antibody diversity is an essential prerequisite for the production of a functional repertoire. While this is essential to prevent infections, it also represents the “Achilles heal” of the B-cell lineage, occasionally leading to malignant transformation of these cells by translocation of protooncogenes into the immunoglobulin (Ig) loci. However, in evolutionary terms this is a small price to pay for a functional immune system. The study of the configuration and rearrangements of the Ig gene loci has contributed extensively to our understanding of the natural history of development of myeloma. In addition to this, the analysis of Ig gene rearrangements in B-cell neoplasms provides information about the clonal origin of the disease, prognosis, as well as providing a clinical useful tool for clonality detection and minimal residual disease monitoring. Herein, we review the data currently available on both Ig gene rearrangements and protein patterns seen in myeloma with the aim of illustrating how this knowledge has contributed to our understanding of the pathobiology of myeloma.