Detection of immunoglobulin gene rearrangement in B lymphoid malignancies by polymerase chain reaction gene amplification

PCR Analysis of IgH and TCR-γ Gene Rearrangements as a Confirmatory Diagnostic Tool for Lymphoproliferative Disorders

This study investigates PCR analysis of immunoglobulin heavy chain (IgH) and T cell receptor (TCR) gene rearrangements on paraffin-embedded tissue sections and bone marrow aspirates of patients suspected to have lymphoproliferative disorders but with inconclusive diagnosis in histopathological examination. 130 samples of patients with inconclusive immunohistochemistry results were evaluated for clonal rearrangement of IgH and TCR genes. Based on histopathology examination, the patients were divided into three groups: the first group without any definite diagnosis of lymphoproliferative disorders (60 cases, 46.2 %), the second group suspected to have a lymphoproliferative disorder but in favor of benign disorders (19 cases, 14.6 %) and the third group suspect to lymphoproliferative disorders but relatively in favor of malignant disorders (51 cases, 39.2 %). After DNA extraction and quality control, semi-nested PCR was performed using consensus primers for amplification of TCR-γ and CDR-3 regions of IgH genes. PCR products were analyzed after heteroduplex analysis using polyacrylamide gel electrophoresis, and were subject to silver staining. Totally, in over half of the cases (55.4 %), a monoclonal pattern was found in IgH or TCR-γ genes rearrangements. Monoclonal IgH gene rearrangement was detected in 48.1 % of patients, whereas monoclonal TCR-γ gene rearrangement was found in 33.6 % of them, which was not statistically significant (P = 0.008). Only in 32 patients (24.6 %) were the results of TCR-γ and IgH gene rearrangements consistent with respect to the presence (2.3 %) or absence (22.3 %) of monoclonality. Finally, PCR analysis of TCR-γ and IgH gene rearrangements led to definite diagnosis in 105 patients (80.8 %), and only 25 cases (19.2 %) remained inconclusive. Our results emphasize the usefulness of gene rearrangement study in cases without a definite diagnosis in immunohistochemistry studies. Multiple PCR analysis results when combined with patient's clinical course and immunohistochemistry can lead to early diagnosis and subsequent therapy.

EuroClonality/BIOMED-2 guidelines for interpretation and reporting of Ig/TCR clonality testing in suspected lymphoproliferations

PCR-based immunoglobulin (Ig)/T-cell receptor (TCR) clonality testing in suspected lymphoproliferations has largely been standardized and has consequently become technically feasible in a routine diagnostic setting. Standardization of the pre-analytical and post-analytical phases is now essential to prevent misinterpretation and incorrect conclusions derived from clonality data. As clonality testing is not a quantitative assay, but rather concerns recognition of molecular patterns, guidelines for reliable interpretation and reporting are mandatory. Here, the EuroClonality (BIOMED-2) consortium summarizes important pre- and post-analytical aspects of clonality testing, provides guidelines for interpretation of clonality testing results, and presents a uniform way to report the results of the Ig/TCR assays. Starting from an immunobiological concept, two levels to report Ig/TCR profiles are discerned: the technical description of individual (multiplex) PCR reactions and the overall molecular conclusion for B and T cells. Collectively, the EuroClonality (BIOMED-2) guidelines and consensus reporting system should help to improve the general performance level of clonality assessment and interpretation, which will directly impact on routine clinical management (standardized best-practice) in patients with suspected lymphoproliferations.

Classification of lymphoid neoplasms: the microscope as a tool for disease discovery

In the past 50 years, we have witnessed explosive growth in the understanding of normal and neoplastic lymphoid cells. B-cell, T-cell, and natural killer (NK)-cell neoplasms in many respects recapitulate normal stages of lymphoid cell differentiation and function, so that they can be to some extent classified according to the corresponding normal stage. Likewise, the molecular mechanisms involved the pathogenesis of lymphomas and lymphoid leukemias are often based on the physiology of the lymphoid cells, capitalizing on deregulated normal physiology by harnessing the promoters of genes essential for lymphocyte function. The clinical manifestations of lymphomas likewise reflect the normal function of lymphoid cells in vivo. The multiparameter approach to classification adopted by the World Health Organization (WHO) classification has been validated in international studies as being highly reproducible, and enhancing the interpretation of clinical and translational studies. In addition, accurate and precise classification of disease entities facilitates the discovery of the molecular basis of lymphoid neoplasms in the basic science laboratory.

Long-term molecular remissions in patients with indolent lymphoma treated with rituximab as a single agent or in combination with interferon alpha-2a: a randomized phase II study from the Nordic Lymphoma Group

The purpose of this phase II randomized trial was to evaluate the effect and safety of interferon-alpha2a (IFN) in combination with extended dosing rituximab in patients with symptomatic, advanced indolent lymphoma responding to a standard single course of rituximab. Totally 123 patients were treated with rituximab 375 mg/m2 once weekly for 4 weeks leading to 14 complete response (CR; 11%), 56 partial response (PR; 46%), and 13 minor responses (MR; 11%). Patients achieving either PR or MR were randomized to four more infusions of rituximab alone (n = 36) or in combination with five weeks of IFN (n = 33), with an overall response rate (CR + PR) of 78% and 94%, respectively. Significantly more patients in the combination arm improved their response from PR/MR to CR (P < 0.05) and more maintained their responses for > or = 24 months (72% versus 50%), respectively. Overall, 26 out of the 52 patients who achieved CR underwent minimal residual disease (MRD) evaluation. Totally 17 of these (65%) achieved MRD negativity, 14 of whom remain in CR after 4.8 years' follow-up. The addition of IFN to rituximab was generally safe, but reversible thrombocytopenia and neutropenia were noted in one and six patients, respectively, requiring a reduction in the IFN dose. Extended rituximab is effective and well tolerated and combination with IFN seems to improve both the quality and duration of the responses, providing the opportunity to achieve long-term molecular CRs and prolonged failure-free survival without chemotherapy.

Aspiration biopsy-nucleic acid diagnosis of thyroid malignant lymphoma by vectorette PCR: experience of eight cases

The usefulness of a new method to detect B-cell monoclonality named VR, which is a combination of the digestion with restriction enzymes and vectorette PCR, in aspiration biopsy-nucleic acid diagnosis (ABND) of thyroid malignant lymphoma was investigated. ABND was performed in 12 patients in whom malignant lymphoma was suspected. Among the patients who underwent open surgery, monoclonality was detected in the aspirates in four (50%) of eight patients with malignant lymphoma, but was not detected in one patient with Hashimoto disease. ABND using VR is a useful adjunct of aspiration biopsy cytology in the diagnosis of thyroid malignant lymphoma.

Detection of monoclonality of the immunoglobulin heavy chain gene in thyroid malignant lymphoma by vectorette polymerase chain reaction

Distinguishing between thyroid malignant lymphoma and lymphocytic thyroiditis (Hashimoto's thyroiditis) is quite difficult and problematic. B cell lymphomas display clonal Ig heavy-chain (IgH) gene rearrangement, and Southern blot hybridization (SBH) is often used for detection of the monoclonality of the IgH gene. However, SBH is often problematic because it requires a large volume of samples. We examined the efficiency in detecting the monoclonality of IgH gene in thyroid malignant lymphomas by vectorette PCR, which we started with only 200 ng of genomic DNA. Monoclonality was detected in 36 of 47 (76.6%) malignant lymphomas, whereas it was not detected in 10 samples of tissue of Hashimoto's thyroiditis. The sensitivity was almost the same as that with SBH in which monoclonality was detected in 33 of 45 (73.3%) malignant lymphomas. These results suggest that vectorette PCR may be a substitute for SBH, and because it requires only a small volume of samples, it may be used in the analysis of aspiration biopsies.

PCR detection of clonal IgH and TCR gene rearrangements at the end of induction as a non-remission criterion in children with ALL: comparison with standard morphologic analysis and risk group classification

BACKGROUND

The initial response to induction therapy is currently considered one of the most important prognostic factors in acute lymphoblastic leukemias (ALL). A series of methods for the detection of submicroscopic levels of residual disease in patients with ALL mainly based on PCR and immunophenotyping has been developed, demonstrating that the presence of high levels of residual disease at the end of induction therapy is an important, independent prognostic factor. We determined the usefulness of PCR detection of minimal residual disease using consensus primers as a non-remission criterion.

PROCEDURE

Bone marrow samples obtained from 49 children with ALL were analyzed at diagnosis and at the end of induction therapy for the detection of clonal IgH, TCRdelta, and TCRgamma rearrangements by PCR. The results were compared with those obtained by standard morphologic analysis and risk group classification.

RESULTS

Patients who had clonality detected at the end of induction showed a significantly higher recurrence rate and lower event-free survival than those without detected clonality (24.9% vs. 89.7%) (P < 0.0001). Multivariate analysis revealed that detection of clonality at the end of induction was the most important, independent prognostic factor when associated with age, number of white blood cells, and immunophenotyping.

CONCLUSIONS

PCR detection of clonality using consensus primers is a relatively simple technique that is able to identify patients with a high chance of recurrence, and shows a higher sensitivity and a better prognostic value than standard morphologic analysis and risk group classification, defining a new remission criterion. However, further multicentric prospective studies using this technique employing a larger number of cases are necessary to confirm these findings.

Rearrangement of immunoglobulin heavy and light chains and VH family in thyroid and salivary gland lymphomas

It is often difficult to differentiate extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) from non-neoplastic inflammatory conditions. Demonstration of clonal lymphoid proliferation by molecular procedures is important for accurate diagnosis. We examined the clonal population of B-cell lymphomas in nine cases of thyroid and two cases of salivary gland B-cell lymphoma using semi-nested polymerase chain reaction (PCR)-based assay for IgH gene arrangement and reverse transcription (RT)-PCR single-strand conformation polymorphism (SSCP) for the detection of IgL gene rearrangement. Clonality was evident in nine out of 11 cases of B-cell lymphomas examined by PCR, and in six of eight cases by RT-PCR SSCP. In addition, analysis of VH families was performed in eight cases. Although VH3 family was frequently used, each case demonstrated the VH4, VH5 or VH6 family. It is possible that the normal counterpart of thyroid or salivary gland lymphoma might be different from peripheral blood B lymphocytes, which usually use VH3 family. Our results indicate that although no clonality was noted in one case by both PCR and SSCP, these molecular methods are useful as supplementary diagnostic tests for both thyroid and salivary gland lymphomas.

Minimal residual disease in Brazilian children with acute lymphoid leukemia: comparison of three detection methods by PCR

The minimal residual disease (MRD) detection by the polymerase chain reaction (PCR) in children with acute lymphoblastic leukemia has been pointed to be an adverse prognostic factor. Detection methods based on this technique using clone-specific primers are cumbersome and time consuming. The detection of monoclonal gene rearrangements of gamma T-cell receptors (TCRgamma) is a simpler although less sensitive method. In the present study, we analyzed the presence of MRD during four different phases of treatment (week 4; 3-6, 12-24 months, and end of treatment) in 34 Brazilian children with lymphoid leukemia by three detection methods based on the PCR technique: (1) using consensus primers for the detection of a clonal population for TCRgamma; (2) clone-specific primers for the junctional region of TCRgamma; and (3) a semi-nested reaction with an initial cycle with consensus primers followed by a second cycle with clone-specific primers. MRD presence was associated with a shorter event-free survival and was the major independent prognostic factor in most of the phases analyzed. The use of consensus primers for the detection of TCRgamma clonality, although less sensitive, proved to be a simpler, faster and less costly method whose positivity was associated with more than 90% relapse rates during all phases analyzed.

Molecular analysis of the immunoglobulin heavy chain gene in the diagnosis of primary cutaneous B cell lymphoma

The diagnosis of primary cutaneous B cell lymphoma can be difficult on the basis of histologic and immunophenotypic features alone. Previous polymerase chain reaction studies for detection of a clonal population in nodal B cell lymphomas have employed different primer pairs with detection sensitivities varying between 34% and 94% but there have been no comprehensive studies of primary cutaneous B cell lymphoma. We compared the sensitivity of different sets of consensus primers to amplify the CDR3 VDJ region of the immunoglobulin heavy chain gene in combination with an immunoglobulin heavy chain joining region consensus primer to detect a monoclonal population in 39 cases of primary cutaneous B cell lymphoma. Radiolabeled products were analyzed with denaturing 6% polyacrylamide gel electrophoresis. Sequence analysis was used to confirm amplification of clonal immunoglobulin heavy chain gene rearrangements and to establish whether somatic hypermutation can interfere with primer binding. Clonal immunoglobulin heavy chain gene rearrangements were demonstrated in 79% of cases (74% with leader sequences, 64% with FR1, and 45% with FR3 primers). Somatic hypermutation at primer binding sites was confirmed in cases where a false negative result was obtained with the FR3 primer. Although monoplex polymerase chain reaction amplification using the leader sequence primers is the most sensitive method for detecting a clonal population, six primers are required in six different reactions. Our findings suggest initial analysis with the FR3 primer and subsequent analysis using leader sequences in negative cases. Our data indicate that the FR3 consensus primer alone is not sufficient for a comprehensive analysis of primary cutaneous B cell lymphoma.

Molecular detection of tumor cells at diagnosis invading the bone marrow and peripheral blood of patients with aggressive or indolent lymphomas

We studied tumor cell invasions of bone marrow and peripheral blood in patients with various types of advanced non-Hodgkin's lymphoma by amplifying complementarity determining region III using the polymerase chain reaction (PCR) method and developing patient-specific probes. After molecular engineering, we could detect tumor cells in bone marrow from seven of 11 cases and in peripheral blood from six of 11 cases, despite negative results in four cases studied morphologically. Indolent cases were more likely to yield positive results than aggressive cases. The reason may be different biological behaviors among the histological types.

Immunoglobulin heavy-chain gene rearrangement in adult acute lymphoblastic leukemia reveals preferential usage of J(H)-proximal variable gene segments

The aim of this study was to characterize individual-segment and overall patterns of V(H) gene usage in adult B-lineage acute lymphoblastic leukemia (ALL). Theoretical values of V(H) segment usage were calculated with the assumption that all V(H) segments capable of undergoing rearrangement have an equal probability of selection for recombination. Leukemic clones from 127 patients with adult B-lineage acute leukemias were studied by fingerprinting by means of primers for the framework 1 and joining segments. Clones from early preimmune B cells (245 alleles identified) show a predominance of V(H)6 family rearrangements and, consequently, do not conform to this hypothesis. However, profiles of V(H) gene family usage in mature B cells, as investigated in peripheral blood (6 samples), B-cell lymphomas (36 clones) and chronic lymphocytic leukemia (56 clones), are in agreement with this theoretical profile. Sequence analyses of 64 V(H) clones in adult ALL revealed that the rate of V(H) usage is proportional to the proximity of the V(H) gene to the J(H) locus and that the relationship can be mathematically defined. Except for V(H)6, no other V(H) gene is excessively used in adult ALL. V(H) pseudogenes are rarely used (n = 2), which implies the existence of early mechanisms in the pathway to B-cell maturation to reduce wasteful V(H)-(D(H))-J(H) recombination. Finally, similar to early immunoglobulin-H rearrangement patterns in the mouse, B cells of ALL derive from a pool of cells more immature than the cells in chronic lymphoid B-cell malignancies.

Acute lymphoblastic leukaemia: correlation between morphological/immunohistochemical and molecular biological findings in bone marrow biopsy specimens

BACKGROUND

Although numerous antibodies suitable for use on paraffin wax embedded sections are available for the subtyping of acute leukaemia (acute myelogenous leukaemia (AML) and acute lymphoblastic leukaemia (ALL)) in bone marrow biopsy sections, unequivocal identification of the cell line involved is sometimes impossible.

METHODS

Forty eight formalin fixed, paraffin wax embedded bone marrow biopsy specimens that had been decalcified in EDTA were investigated, including 42 thought to exhibit ALL on the basis of bone marrow smears. Five specimens exhibited AML and one biphenotypic leukaemia, as diagnosed immunohistochemically in bone marrow biopsies. Immunostaining was performed with antibodies against relatively specific B and T cell antigens. The blasts were investigated for rearrangements of the immunoglobulin heavy chain (IgH) and the T cell antigen receptor (TCR) genes.

RESULTS

Amplifiable DNA was obtained from all 48 specimens. An IgH gene rearrangement was detected in 20 of 23 c-ALL specimens. Four of seven T cell ALL (T-ALL) specimens had a TCR-gamma gene rearrangement, and the one B cell ALL (B-ALL) specimen exhibited a clonal IgH gene. Three of four cases of unclassifiable ALL could be assigned to the B cell lineage on the basis of gene rearrangement analysis. Seven cases originally diagnosed in smears as ALL were rediagnosed as AML (n = 5) or biphenotypic leukaemia (n = 2) because of immunohistochemical reactivity for myeloperoxidase or lysozyme. Two of these AML cases and two of three cases of biphenotypic leukaemia exhibited a monoclonal IgH gene rearrangement.

CONCLUSIONS

Acute leukaemia can be subtyped in bone marrow sections with a limited panel of antibodies suitable for use on paraffin wax embedded sections (against CD3, CD10, CD20, CD79a, myeloperoxidase, and lysozyme). In patients with ALL and a diagnostically equivocal immunophenotype, gene rearrangement analysis might indicate whether the B or T cell lineage is involved.

Hypermethylation of P16ink4a and P15ink4b genes as a marker of disease in the follow-up of non-Hodgkin's lymphomas

The hypermethylation of p16ink4a and p15ink4b genes have been described as an inactivating mechanism alternative to deletions and mutations that accounts for a relatively high proportion of cancers, including non-Hodgkin's lymphomas (NHLs). To investigate whether detection of abnormal methylation could have clinical applications in the management and follow-up of lymphomas, we have analysed the behaviour and evolution of p16ink4a and p15ink4b methylation in 13 NHL cases undergoing chemotherapy. All cases were also analysed for the presence of monoclonal rearrangements of immunoglobulin or T-cell receptor genes. Six patients showed methylation in at least one of these genes at diagnosis, whereas in two other cases methylation appeared during the treatment. The other five cases were always unmethylated. Methylation was detected when any histological or molecular evidence of disease was present, suggesting a good correlation between methylation and disease. In some cases, we were able to detect methylation in patients at complete remission and without evidence of monoclonal cell population, indicating a high sensitivity of the PCR to detect methylation. These results suggest that p16ink4a and p15ink4b methylation could be good markers of disease and could be helpful in identifying lymphoma patients at risk of relapse.

Detection of clonally restricted immunoglobulin heavy chain gene rearrangements in normal and lesional skin: analysis of the B cell component of the skin-associated lymphoid tissue and implications for the molecular diagnosis of cutaneous B cell lymphomas

A monoclonal B cell population is the hallmark of B cell neoplasms including cutaneous B cell lymphomas (CBCLs). We modified and tested several polymerase chain reaction (PCR)-based assays involving amplification of immunoglobulin heavy chain (IgH) gene rearrangements to optimize assays specifically for cutaneous lymphoid infiltrates. We achieved greatest sensitivity with an assay employing IgH consensus primers complementary to the framework 3 portion of the upstream variable region and the downstream joining region. We studied 12 CBCLs, 6 nodal lymphomas and 7 cell lines. In 17/25 of these B cell neoplasms (84%), we detected one or two dominant bands, consistent with one or both IgH alleles being rearranged in the neoplastic B cell clone. As expected, IgH PCR assays produced diffuse smears in agarose gels or complex ladders in polyacrylamide gels when polyclonal B cell controls (blood and tonsil) were analyzed. However, in normal skin and non-CBCL skin lesions, one or a small number of discrete bands were sometimes detected. In certain cases, this made it difficult to distinguish true positives (monoclonal CBCL) from false positives (clonally restricted benign B cells). Correlation with immunophenotyping confirmed that false positive results were confined to samples with sparse or immunohistologically undetectable B cell infiltrates. Pseudoclonal bands showed variable sizes in repeat PCR reactions and could be distinguished from monoclonal bands by polyacrylamide gel electrophoresis of pooled triplicate PCR products. These findings suggest that molecular diagnosis using IgH PCR assays is best suited for B-cell-rich infiltrates, and can be problematic when applied to suspected T-cell-rich CBCLs, cutaneous T cell lymphomas, or other lesions containing only few B cells unless one is cognizant of the potential pitfalls. Furthermore, these results demonstrate the presence of rare B cells in normal skin and immunohistologically defined cutaneous T cell infiltrates. This correlates with recent reports of sparse B cells within the lymph draining from normal skin and may represent molecular evidence for a trafficking B cell component of the skin-associated lymphoid tissue (SALT). It also suggests a candidate B cell subset for the pathogenesis of cutaneous lymphoid hyperplasia and CBCLs.

Diagnosis of thyroid malignant lymphoma by reverse transcription-polymerase chain reaction detecting the monoclonality of immunoglobulin heavy chain messenger ribonucleic acid

Distinguishing between thyroid malignant lymphoma and lymphocytic thyroiditis (Hashimoto's thyroiditis) is quite difficult and problematic. Molecular techniques to detect clonal lymphoid proliferation based on Ig heavy chain (IgH) gene rearrangement may be used to facilitate more accurate diagnosis of malignant lymphoma. We recently established a method for diagnosing thyroid tumors by analyzing ribonucleic acids (RNAs) extracted from the needles used for fine needle aspiration biopsy (aspiration biopsy-RT-PCR). By applying the aspiration biopsy-RT-PCR method to detection of the monoclonality of IgH messenger RNA (mRNA), an accurate molecular-based diagnosis of malignant lymphoma can be established as an adjunct to cytological diagnosis. We first studied RNAs from fresh tissues samples of 8 cases of Hashimoto's thyroiditis and 18 malignant lymphomas to detect the monoclonality of IgH mRNA by seminested RT-PCR. Monoclonality was detected in 8 of 18 (44.4%) malignant lymphomas, but in none of the 8 cases of Hashimoto's thyroiditis. We then studied aspirates from 10 cases of thyroid malignant lymphoma, 4 cases of Hashimoto's thyroiditis, and 1 case each of adenomatous goiter and papillary carcinoma. Monoclonality was detected in the aspirates from 4 of 10 malignant lymphomas (40%), but not from other tissues. Thus, RT-PCR detection of monoclonality of IgH mRNA in addition to cytological examination may be useful in diagnosing thyroid malignant lymphoma.

Clonal identities and multiple isotype transcripts in hematological diseases revealed by a single-strand conformation polymorphism analysis of the immunoglobulin heavy chain messenger signals

A single-strand conformation polymorphism (SSCP) analysis of polymerase chain reaction (PCR)-amplified products of immunoglobulin (Ig) heavy chain rearrangements can be used to analyze B cell clonalities and clonal identities of B cells from different samples. However, the usefulness of the PCR-SSCP analysis is not fully assessed in B cell malignancies. For example, we did not know whether the PCR-SSCP method can be used to detect tumor-related clones in peripheral blood of patients with multiple myeloma and Waldenström's macroglobulinemia. In addition, because genomic DNA is used in the PCR-SSCP method, we could obtain no information about the isotype of the expanded B cell clone. In this study, we combined the reverse transcriptase (RT)-PCR of immunoglobulin heavy chain transcripts with an SSCP analysis and thus analyzed eight healthy individuals, five patients with B chronic lymphocytic leukemia, four patients with multiple myeloma and three patients with Waldenström's macroglobulinemia. Clonal B cell populations were detected as discrete bands in the RT-PCR-SSCP analysis that can be readily detected over the background of polyclonal rearrangements. Circulating tumor-related clones were detected in all but one peripheral blood sample from multiple myeloma and Waldenström's macroglobulinemia patients and B cell clones in peripheral blood and bone marrow from these patients showed a similar mobility on SSCP gel. Because the transcripts of different isotypes were separately analyzed, we could thus determine the isotype of B cell clones as well. When monoclonal Igs of different isotypes were detected in the individual samples, we analyzed the relationship of each monoclonal band by excising the band and then further analyzing it by a PCR-SSCP analysis. RT-PCR amplification in conjunction with the SSCP analysis is thus considered to be a useful method to detect and characterize the B cell clones in hematological diseases.

Staphylococcus aureus Cowan strain 1 activation of B-chronic lymphocytic leukaemia cells augments the response to CD40 stimulation

The signals involved in regulating the proliferation, differentiation and survival of B-chronic lymphocytic leukemia (B-CLL) cells are fully understood. B-CLL cells have been found to respond poorly to various activation signals and only after successful Epstein-Barr virus (EBV) transformation has it been possible to maintain such cells in long-term cultures. In this work we describe a new method to activate and induce proliferation in B-CLL cells and to maintain such cells in long-term culture for longer than 1 month. We used a combination of protocols in an attempt to mimic some of the signals of a thymus-dependent immune response. The B-CLL cells were first activated with Staphylococcus aureus Cowan strain 1 (SAC) particles plus thioredoxin (Trx), followed by stimulation with interleukin (IL)-2 + Trx. This treatment primed the cells for further stimulation with anti-CD40 monoclonal antibody (MoAb) presented on irradiated CD32L cells (the CD40-system) or soluble CD40 Ligand, and a combination of Trx and cytokines (IL-4 + IL-10), which allowed the cells to be maintained for up to 1 month with preserved viability and a variable rate of proliferation. However, induced proliferation of the B-CLL cells was limited to approximately 1 month, suggesting that additional signals are required to facilitate further proliferation.

Detection of immunoglobulin kappa light chain rearrangements by polymerase chain reaction. An improved method for detecting clonal B-cell lymphoproliferative disorders

The clonal determination of B-cell lymphoproliferative disorders by immunoglobulin heavy chain (IgH) rearrangement by polymerase chain reaction (PCR) is widely used. However, few attempts have been made to detect immunoglobulin kappa light chain (Igkappa) gene rearrangement using PCR. We studied 145 cases of B-cell neoplasms, along with 58 atypical and 18 reactive lymphoproliferative disorders, using newly designed degenerate oligoprimers recognizing the framework 3 (FR3kappa) and the joint (Jkappa) regions of the Igkappa gene. PCR products were analyzed on nondenaturing polyacrylamide gel (ndPAGE). Clonal B-cell determination was further investigated using IgH rearrangement and t(11:14) or t(14:18). By combining these methods, we detected either clonality or translocation in 117 of 137 cases (85%) in mature B-cell neoplasms. The additional analysis of Igkappa rearrangement improved sensitivity from 66% to 85%. To investigate whether the Ig gene configuration could be characterized using Igkappa PCR in B-cell neoplasms showing severe breakdown of genomic DNA, 18 selected cases were analyzed. Successful amplification was detected in 72% of the cases using either FR3/2-JH and/or FR3Jkappa oligoprimers. Finally, clonality was detected in 21 of 58 atypical B-cell proliferations, and among them, the atypical marginal cell (54%) and atypical large cell (50%) proliferations showed the highest frequency of clonal immunoglobulin gene products. We concluded that PCR/ndPAGE analysis of Igkappa is a sensitive, rapid, and efficient method for assessing clonality in conjunction with IgH and specific translocation analysis. This approach is particularly useful in the characterization of B-cell lymphoproliferative disorders in archival material with poor preservation of the genomic DNA.

Reactive and neoplastic lymphocytes in human bone marrow: morphological, immunohistological, and molecular biological investigations on biopsy specimens

BACKGROUND

Slight, diffuse or focal lymphocyte proliferation is relatively common in bone marrow biopsy specimens. It may be impossible to determine whether this represents a reactive lymphocytosis or low grade non-Hodgkin lymphoma (NHL) on the basis of routine investigations alone.

AIM

To investigate the supplementary use of molecular biological techniques in this situation.

METHODS

529 formalin fixed, paraffin embedded bone marrow biopsy specimens from the iliac crest were subjected to histological and immunohistochemical staining to determine the number and nature of the lymphocytes present. The cases were divided into three groups according to the lymphocyte count: normal (< 10% of nucleated bone marrow cells), slightly increased (10-30%), and markedly increased (> 30%). All of the last group could be diagnosed as NHL from the morphological findings alone. The clonality of rearrangements of the IgH and TCR gamma genes was investigated by polymerase chain reaction (PCR).

RESULTS

Monoclonality was observed in 7.5% of the 372 cases with a normal lymphocyte count, in 50% of the cases with a modest increase in lymphocyte numbers (suggesting a diagnosis of low grade NHL not detected by immunostaining), and in 77% of the cases with markedly increased lymphocyte numbers.

CONCLUSIONS

If PCR is used in addition to the immunohistochemical investigation of bone marrow biopsies, considerably more cases of NHL can be identified, making this of particular use in staging and detection of recurrences.

B-cell pulmonary lymphoma: gene rearrangement analysis of bronchoalveolar lymphocytes by polymerase chain reaction

STUDY OBJECTIVES

Non-Hodgkin's lymphomas (NHLs) are clonal proliferation of B or T lymphocytes. Assessment of clonality in lymphoid proliferations uses immunochemistry and, recently, molecular biology. The aim of our study is to assess the role of immunoglobulin gene rearrangement analysis on bronchoalveolar lymphocytes to aid in the diagnosis of B-cell pulmonary NHL.

PATIENTS AND METHODS

The study took place in a university hospital. There were seven consecutive patients with B-cell-type pulmonary lymphoma and nine control subjects. Gene rearrangement analysis using polymerase chain reaction (PCR) technique was performed on alveolar lymphocytes recovered by BAL.

RESULTS

Analysis of the immunoglobulin heavy chain gene rearrangement showed a predominant clonal alveolar lymphocyte population in six of seven patients while all control subjects showed germline pattern.

CONCLUSIONS

Gene rearrangement analysis by PCR of alveolar lymphocytes would appear to be sensitive in patients with B-cell pulmonary NHL (six of seven patients) and specific (zero of nine in the control group). This simple test should be added only in the analysis of cells recovered by BAL in patients with suspected primary and secondary B-cell pulmonary NHL.

Establishment of a novel B cell clonality analysis using single-strand conformation polymorphism of immunoglobulin light chain messenger signals

The remarkable diversity of the complementarity determining region (CDR) 3 of the immunoglobulin (Ig) heavy (H) chain gene rearrangements has been exploited to identify the clonal populations of B cells in B cell malignancies. However, when B cell malignancies of different categories were examined, the overall detection rate was found to be approximately 70%. The development of a simple clonality analysis using Ig light (L) chain CDR3 diversity has been hampered due to the sparseness of knowledge regarding the sequence of Vkappa and Vlambda gene segments and the restriction of L chain CDR3 length. Based on the recently reported Vkappa and Vlambda gene sequences, we designed Vkappa and Vlambda framework 3 consensus primers. We combined the reverse transcriptase polymerase chain reaction (RT-PCR) of IgL chain transcripts with a single-strand conformation polymorphism (SSCP) analysis and then analyzed samples from patients with B cell malignancies. Clonal B cell populations were detected as discrete bands, and identical clones showed a similar mobility in a RT-PCR SSCP analysis. This method was thus found to be a useful supplement to the previously described approach of VH gene amplification for detecting clonal B cell populations. By using SSCP, we were able to determine the clonal identities of B cell expansion in different samples.

Detection of Clonal Hodgkin and Reed-Sternberg Cells With Identical Somatically Mutated and Rearranged VH Genes in Different Biopsies in Relapsed Hodgkin’s Disease

Hodgkin’s disease (HD) represents a malignant lymphoma in which the putative malignant Hodgkin and Reed-Sternberg (H-RS) cells are rare and surrounded by abundant reactive cells. Single-cell analyses showed that H-RS cells regularly bear clonal Ig gene rearrangements. However, there is little information on the clinical evolution of HD in a given patient. In this study, we used the single-cell polymerase chain reaction (PCR) to identify H-RS cells with clonal Ig gene rearrangements in biopsy specimens of patients with relapsed HD. The obtained clonal variable region heavy-chain (VH) gene rearrangements were used to construct tumor-clone-specific oligonucleotides spanning the complementarity determining region (CDR) III and somatically mutated areas in the rearranged VHgene. A number of biopsies were obtained during a period of 3 years from two HD patients. H-RS cells with identical VHrearrangements were detected in two separate infiltrated lymph nodes from one patient with nodular sclerosis HD. In a second patient with mixed cellularity HD subtype, clonal VH rearrangements with identical sequences were detected in infiltrated spleen and two lymph node biopsies. Despite the high sensitivity of the PCR method used (one clonal cell in 105 mononuclear cells), residual H-RS cells were not found in peripheral blood, leukapheresis material, purified CD34+ stem cells or bone marrow. The results show that different specimens from relapsed patients suffering from classical HD carry the same clonotypic IgH rearrangements with identical somatic mutations, demonstrating the persistence and the dissemination of a clonal tumor cell population. Thus, PCR assays with CDRIII-specific probes derived from clonal H-RS cells are of clinical importance in monitoring the dissemination of HD and tumor progression and could be useful for analysis of minimal residual disease after autologous stem cell transplantation.

© 1998 by The American Society of Hematology.

Detection of Clonal Hodgkin and Reed-Sternberg Cells With Identical Somatically Mutated and Rearranged VH Genes in Different Biopsies in Relapsed Hodgkin’s Disease

Hodgkin’s disease (HD) represents a malignant lymphoma in which the putative malignant Hodgkin and Reed-Sternberg (H-RS) cells are rare and surrounded by abundant reactive cells. Single-cell analyses showed that H-RS cells regularly bear clonal Ig gene rearrangements. However, there is little information on the clinical evolution of HD in a given patient. In this study, we used the single-cell polymerase chain reaction (PCR) to identify H-RS cells with clonal Ig gene rearrangements in biopsy specimens of patients with relapsed HD. The obtained clonal variable region heavy-chain (VH) gene rearrangements were used to construct tumor-clone-specific oligonucleotides spanning the complementarity determining region (CDR) III and somatically mutated areas in the rearranged VHgene. A number of biopsies were obtained during a period of 3 years from two HD patients. H-RS cells with identical VHrearrangements were detected in two separate infiltrated lymph nodes from one patient with nodular sclerosis HD. In a second patient with mixed cellularity HD subtype, clonal VH rearrangements with identical sequences were detected in infiltrated spleen and two lymph node biopsies. Despite the high sensitivity of the PCR method used (one clonal cell in 105 mononuclear cells), residual H-RS cells were not found in peripheral blood, leukapheresis material, purified CD34+ stem cells or bone marrow. The results show that different specimens from relapsed patients suffering from classical HD carry the same clonotypic IgH rearrangements with identical somatic mutations, demonstrating the persistence and the dissemination of a clonal tumor cell population. Thus, PCR assays with CDRIII-specific probes derived from clonal H-RS cells are of clinical importance in monitoring the dissemination of HD and tumor progression and could be useful for analysis of minimal residual disease after autologous stem cell transplantation.

© 1998 by The American Society of Hematology.

Polymerase chain reaction-single-strand conformational polymorphism analysis of antigen receptor rearrangements in monitoring therapeutic effect in childhood ALL

The rearrangement of the immunoglobulin heavy chain (IgH) genes can be used as a marker of cell lineage and clonality. The polymerase chain reaction (PCR) technique using consensus primers for the IgH gene was used for remission and minimal residual disease (MRD) analysis in the follow-up of childhood acute lymphoblastic leukemia (ALL) of B-cell lineage. Single-strand conformational polymorphism (SSCP) was used to distinguish the specific clonal amplicons from the background. The Authors found that, in a series of 22 patients followed-up for 5.3 to 11.1 years, the PCR-SSCP technique could detect at least one rearrangement at initial diagnosis in 21 (95%). All patients who remained in continuous complete remission were PCR-SSCP negative at remission controls. Ten of the 22 patients had one or more bone marrow relapses. The PCR-SSCP method demonstrated MRD in three of them. In 6 of the 7 (86%) of patients with disease recurrence from whom samples were taken within 6 months before a clinically overt relapse, PCR-SSCP became positive. The Authors conclude that PCR-SSCP of a rearrangement marker might have a role as a convenient technique for monitoring emerging relapse. It may also detect unrelated clones or ongoing secondary recombination events during progression. However, PCR-SSCP is not sensitive enough to detect MRD in all patients in whom disease will later recur.

Idiotype Immunization Combined With Granulocyte-Macrophage Colony-Stimulating Factor in Myeloma Patients Induced Type I, Major Histocompatibility Complex–Restricted, CD8- and CD4-Specific T-Cell Responses

Idiotypic structures expressed on the myeloma Ig protein might be regarded as a tumor-specific antigen. Five patients with IgG myeloma were immunized with the purified serum M-component by repeated intradermal injections together with soluble granulocyte-macrophage colony-stimulating factor (GM-CSF). All patients developed an idiotype (Id)-specific T-cell immunity, defined as blood T cells predominantly secreting interferon-γ (IFN-γ) and interleukin-2 (IL-2) (type I cells). Id-specific DNA synthesis was induced in one patient. Delayed-type hypersensitivity against the Id was not evoked. The specific IFN-γ/IL-2 T-cell response was inhibited (46% to 100%) by a major histocompatibility complex (MHC) class I monoclonal antibody (MoAb) in all five patients. A 5% to 37% inhibition by an MHC class II MoAb was seen in four patients. CD4+ as well as CD8+ T cells enriched by magnetic microbeads contained Id-specific cells. The T cells recognized peptides corresponding to the complementarity-determining regions 1, 2, and 3 of the heavy chain of the Id. There was a transient rise of B cells producing IgM anti-idiotypic antibodies in all patients. The results indicate that immunization of myeloma patients using the autologous M-component and soluble GM-CSF may evoke an Id-specific predominantly MHC class I–restricted type I T-cell response.

Idiotype Immunization Combined With Granulocyte-Macrophage Colony-Stimulating Factor in Myeloma Patients Induced Type I, Major Histocompatibility Complex–Restricted, CD8- and CD4-Specific T-Cell Responses

Idiotypic structures expressed on the myeloma Ig protein might be regarded as a tumor-specific antigen. Five patients with IgG myeloma were immunized with the purified serum M-component by repeated intradermal injections together with soluble granulocyte-macrophage colony-stimulating factor (GM-CSF). All patients developed an idiotype (Id)-specific T-cell immunity, defined as blood T cells predominantly secreting interferon-γ (IFN-γ) and interleukin-2 (IL-2) (type I cells). Id-specific DNA synthesis was induced in one patient. Delayed-type hypersensitivity against the Id was not evoked. The specific IFN-γ/IL-2 T-cell response was inhibited (46% to 100%) by a major histocompatibility complex (MHC) class I monoclonal antibody (MoAb) in all five patients. A 5% to 37% inhibition by an MHC class II MoAb was seen in four patients. CD4+ as well as CD8+ T cells enriched by magnetic microbeads contained Id-specific cells. The T cells recognized peptides corresponding to the complementarity-determining regions 1, 2, and 3 of the heavy chain of the Id. There was a transient rise of B cells producing IgM anti-idiotypic antibodies in all patients. The results indicate that immunization of myeloma patients using the autologous M-component and soluble GM-CSF may evoke an Id-specific predominantly MHC class I–restricted type I T-cell response.

Comparison of in situ hybridisation and polymerase chain reaction in the diagnosis of B cell lymphoma

AIM

To compare the sensitivity of the detection of immunoglobulin light chain messenger RNA (mRNA) restriction by in situ hybridisation (ISH) and clonal immunoglobulin heavy chain gene rearrangements by polymerase chain reaction (PCR) in the diagnosis of B cell lymphoma.

METHODS

Analyses were applied to formalin fixed, paraffin wax embedded, routine diagnostic specimens from cases with a provisional diagnosis of reactive lymph node (n = 23), B cell lymphoma (n = 21), and T cell lymphoma (n = 4). Nonisotopic ISH for kappa and lambda immunoglobulin light chain mRNA was performed using both fluorescein and digoxigenin labelled oligodeoxynucleotide probe cocktails. PCR was carried out on DNA extracted from sections using primers to framework 3 (Fr3) of the V segments and to conserved sequences from the J regions of the immunoglobulin heavy chain genes.

RESULTS

All reactive lymph nodes showed a polyclonal pattern of light chain mRNA by ISH, although one showed an excess of kappa positive cells. Nineteen of 21 (90%) cases of B cell lymphoma showed light chain restriction, and a further case showed a vast excess of kappa positive cells. By PCR, 20 of 23 reactive nodes (87%) showed a polyclonal pattern. In 13 of 21 B cell lymphomas (62%) a clonal band was detected.

CONCLUSION

In the diagnosis of B cell lymphoma in routinely processed diagnostic material ISH for light chain mRNA was more sensitive (90%) than PCR for heavy chain gene rearrangement using Fr3 and J region primers (62%).

Childhood B lineage acute lymphoblastic leukemia clonality study by the polymerase chain reaction

PURPOSE

B cell precursors acute lymphoblastic leukemia (ALL) present rearrangements in the heavy chain immunoglobulin and T cell receptor genes, especially in the complementarity determining region 3 (CDR-3) and T cell receptor delta (TCR delta) (V delta 2 D delta 3) regions. These rearrangements may be amplified by the polymerase chain reaction (PCR) and used as clonal markers of B lineage ALL. Our purpose was to study clonality at the DNA level by PCR in B lineage ALL.

PATIENTS AND METHODS

Fifty-three pediatric patients (36 with B lineage ALL, 7 with ALL-T, and 10 with nonlymphocytic disease) were investigated using consensus primers for the CDR-3 regions of IgH and TCR delta.

RESULTS

Clonality was detected in 86.1% of the patients with B lineage ALL when the primers for the CDR-3 regions were used, in 41.6% when the primers for TCR delta were used, and in 91.6% when the two primers were used together. Biclonality was found in 22.5% and 6.6% of patients that have shown clonality for CDR-3 and TCR delta, respectively. Clonality was not detected in any other samples using these primers.

CONCLUSIONS

PCR using CDR-3 and TCR delta primers can be used as an aid for B lineage ALL diagnosis and clonal evolution of theses disease.

Polymerase chain reaction-based detection of B-cell clonality in the fine needle aspiration biopsy of a thyroid mucosa-associated lymphoid tissue (MALT) lymphoma

Although it is possible to diagnose primary high-grade thyroid lymphoma from a fine needle aspiration (FNA) biopsy, the distinction of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) from lymphocytic thyroiditis is sometimes problematic. Definitive diagnosis of lymphoma on cytologic specimens may be facilitated by the documentation of a clonal lymphoid proliferation within the specimen by flow cytometric immunophenotyping or immunocytochemistry. Recently, molecular techniques have also been developed to detect clonal lymphoid proliferation based on immunoglobulin (Ig) or T-cell receptor gene rearrangement. We have used a polymerase chain reaction (PCR)-based assay for Ig heavy chain gene arrangement to identify a clonal population of lymphocytes within the thyroid FNA specimen from a low-grade thyroid MALT lymphoma. Using this assay, we identified no distinct clonal population in five cytologic specimens of lymphocytic thyroiditis. Therefore, this PCR-based clonality assay represents a potentially useful adjunct to the cytologic diagnosis of thyroid lymphoma.

Application of polymerase chain reaction to detect rearrangement of immunoglobulin heavy chain genes in lymphoproliferative disease

As part of our routine work-up in the diagnosis of lymphoproliferative disease, we used a rapid polymerase chain reaction (PCR) assay to amplify the DNA fragments of the framework 3 (FR3) region of the immunoglobulin heavy (IgH) chain genes. The assay does not involve hybridization, nested priming, or sequencing of the amplified PCR product. It was performed on 66 specimens of B-cell lymphoproliferative disease, including acute lymphoblastic leukemia, chronic lymphocytic leukemia, multiple myeloma, hairy cell leukemia and follicular lymphoma. Twenty-six specimens of negative controls, including acute myeloid leukemia, chronic myeloid leukemia in myeloid transformation and idiopathic thrombocytopenic purpura, were also analyzed. The assay was performed with 77% sensitivity and 100% specificity. The standard IgH chain gene rearrangement by Southern blot analysis is reserved for the remaining negative cases if clinically indicated.

Amplification of third-complementary-determining-region (CDR-III) of heavy chain immunoglobulin gene (IgH) in one hundred adult acute leukemias

We applied a simple polymerase chain reaction (PCR) based method for detecting immunoglobulin heavy-chain (IgH) gene rearrangement, using its CDR-III region to assess B-cell clonality in a series of 100 acute lymphoblastic leukemias (ALL) (84 B-cell lineage, 4 null-ALL and 12 T-ALL). The amplified CDR-III regions can be generated in all the B-lineage ALL and separated by size by polyacrylamide gel electrophoresis (PAGE), thereby providing a specific diagnostic marker for each B cell clone. Size heterogeneity resulting from independent IgH rearrangement events and the high resolution power after electrophoresis and silver staining of the PAGE gels can be used to generate a "fingerprint" of the PCR fragments representing either the spectrum of B-cell clonality in complex populations of B lymphocytes or the partially genomic configuration of the VH-N-DH-N-JH region. At diagnosis, we found the presence of one clonal IgH heavy-chain gene rearrangement in 80 B-cell lineage and null ALL and a biclonal rearrangement in 8 cases. The CDR-III bands were of sizes ranging from 80 to 130 bp. The PCR analysis of the IgH gene enabled us to obtain a CDR-III leukemia specific product in all cases, thereby providing a specific and diagnostic marker for each B-cell clone.

IgM-producing chronic lymphocytic leukemia cells undergo immunoglobulin isotype-switching without acquiring somatic mutations

The malignant B cells in chronic lymphocytic leukemia (CLL) typically express low-density membrane IgM or IgM/IgD. In vitro experiments have shown that the CLL cells can be induced to differentiate into cells that secrete immunoglobulin (Ig) and can occasionally undergo heavy (H) chain class switching. We now show that the CLL cells also undergo isotype-switching in vivo, since gamma and/or alpha H chain transcripts with identical FW3/CDR3/FW4 regions as the mu CLL transcripts were detected in all of the 13 investigated patients with IgM+ CLL. In most cases switching had occurred to alpha1 and gamma3, but CLL transcripts corresponding to the other gamma chain isotypes were also detected. In one case both the productively and nonproductively rearranged allele were found to undergo H chain class switching. CLL gamma transcripts were also present in surface IgG+ sorted B cells, demonstrating that a small subset of the CLL cells express membrane IgG. In addition, transcripts encoding secretary gamma2 and gamma3 H chains were detected in two cases, which suggests that some serum IgG could be produced by the leukemic clone. Analysis of sorted PBL showed that isotype-switching occurs in CLL cells that express the CD5 antigen. Finally, nucleotide sequence analysis showed that the mu, alpha, and gamma CLL transcripts are identical, demonstrating that the CLL cells do not accumulate somatic mutations in their variable region genes after the H chain class switching. These data provide in vivo evidence that isotype-switching is a frequent phenomenon in CLL, and indicate that a subset of the CLL lymphocytes progress to later stages of B cell differentiation.

Polymerase chain reaction in the detection of micrometastases and circulating tumor cells

BACKGROUND

The sensitive detection of circulating tumor cells and micrometastases may have important therapeutic and prognostic implications.

METHODS

The molecular detection of occult tumor cells can be accomplished by amplifying tumor specific abnormalities present in the DNA or mRNA of malignant cells with the polymerase chain reaction (PCR). This approach has been used mainly for hemato-lymphoid malignancies. The other main PCR strategy for the detection of minimal residual disease (MRD) involves amplification of tissue-specific mRNA. This method was applied for the detection of occult disease in solid tumors.

RESULTS

PCR was shown to be superior to conventional techniques in detecting circulating tumor cells and micrometastases allowing the identification of 1 tumor cell diluted with 10(6)-10(7) normal cells. The central question of whether PCR positivity reliably predicts relapse remains unanswered for many tumor types. Serial analysis of a large number of samples is needed and currently undertaken in many institutions.

CONCLUSIONS

PCR is a highly sensitive method for the detection of circulating tumor cells and micrometastases in solid and hematopoietic malignancies. If PCR positivity is found to be a reliable tool, this will likely have a major impact on the treatment of many cancers. Patients could be selected for systemic therapy at an earlier stage when the metastatic tumor burden is low. PCR may improve the preoperative staging of patients with epithelial malignancies and therefore help avoid unnecessary radical procedures. Furthermore, this test may be useful in monitoring the effectiveness of adjuvant therapy, the intensity and duration of which is tailored to the individual patient. The impact of this PCR based approach on clinical oncology is likely to be profound.

The role of haematopoietic stem cell-supported myeloablative therapy for the management of multiple myeloma

Haematopoietic stem cell-supported myeloablative therapy appears to be a promising treatment modality for MM. It yields increased overall response and CR rates when compared with conventional chemotherapy, and seems to prolong the duration of survival. These conclusions, while encouraging, have mostly been drawn from uncontrolled studies carried out in select groups of patients and, obviously, need to be confirmed in controlled clinical trials. While the results of these studies are still awaited, the wider application of BMT should probably be encouraged. As in other malignancies, the best candidates appear to be those less heavily pre-treated, with chemosensitive disease, low tumour cell mass and other favourable prognostic features, for example low beta 2-microglobulin levels. Under these conditions, the chance of entering CR following BMT, be it autologous or allogeneic, is currently estimated to be of at least 50%, and the long-term probability of survival averages approximately 30%. However, while it appears that a plateau for progression-free survival cannot be ascertained following a single ABMT, reported observations of patients with continued disease-free survivals up to and beyond 10 years after allografting suggest that this latter procedure may be curative. It seems likely therefore that the higher mortality related to allogeneic BMT (which in recent years decreased from 50% to approximately 30% as the results of a better selection of patients and increasing experience in their management) may be offset by more durable control of the disease and cure in a certain proportion of patients. Recurrence of underlying malignant disease remains, however, a major problem and is the most common cause of treatment failure following BMT. For this reason, attempts to improve the impact of transplantation are warranted. Options currently under investigation include the development of more effective conditioning regimens, as applied in double auto-transplant or with targeted therapy using antibody-radionuclide conjugates, as well as post-transplant immunomodulation with either IFN-alpha, interleukin-2 or idiotype vaccines. In addition, many other problems regarding BMT for MM are still unresolved and could be properly addressed only in future clinical trials. The most important of these issues include the choice of the best conditioning regimen and the optimal source of haematopoietic stem cells, the nature of relapse after autografting, the need to purge or not to purge the autologous marrow, the existence of a 'graft-versus-myeloma' effect and its role in prolonging the duration of disease control and, finally, the likelihood of cure, especially for patients with molecularly-defined CR.

The usefulness of a rapid PCR methodology to detect rearranged Ig heavy chain genes in lymphoproliferative disease in a diagnostic setting

Polymerase chain reaction (PCR) was used to amplify the DNA fragments of the framework 3 region (FR3) of the immunoglobulin heavy (IgH) chain genes, from the tissue of 66 patients with B-lymphoproliferative diseases and 74 patients with other malignant diseases, reactive or normal tissue. The assay performed with 77% sensitivity, 100% specificity and 89% efficacy. In addition, the PCR assay cost less than 25% of the cost performing Southern blot analysis of tumor DNA, which has been the test performed to date, and had a turn around time of 24 hrs rather than the 7-14 days required to obtain a result from Southern blot analysis. These results suggest that PCR analysis of B-cell lymphoproliferative disease is superior to Southern blot analysis, in the setting of a diagnostic laboratory.

The clonogenic precursor cell in multiple myeloma

Multiple myeloma is characterized by the monoclonal expansion of plasma cells in the bone marrow. Although the predominant cell type is the plasma cell, the initial oncogenic transformation is considered to take place in a more immature B cell. There is still much controversy about this precursor cell type. Phenotypic analysis of bone marrow and peripheral blood revealed that in multiple myeloma a great diversity exists in the phenotype of the cells considered to be involved. Because of the lack of a myeloma specific genetic lesion it is very difficult to trace back the cell in which the transforming event, leading to multiple myeloma, took place. The only real clonal marker is the idiotype of the immunoglobulin molecule expressed by the myeloma cells. With recombinant DNA technology it is now possible to produce clonal markers for each individual myeloma patient which recognize only the immunoglobulin genes expressed by the myeloma cell and its precursors. The sequences of these myeloma immunoglobulin genes do reveal a lot of information about the stage in the B-cell differentiation pathway in which the oncogenic event might have taken place. The presence of somatic mutations in a non-random fashion without intraclonal variation leads to the conclusion that the precursor myeloma cell could not possibly be a pre-B cell or stem cell but has to be a mature B cell that has been in contact with antigen and has past through the phase of somatic mutation, like a memory B cell or plasmablast.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of minimal residual disease in acute promyelocytic leukaemia with t(15;17) by chromosome painting

To detect the minimal residual disease (MRD) in acute promyelocytic leukaemia patients treated with all-trans retinoic acid, we compared the sensitivity of metaphase fluorescence in situ hybridization (FISH) with conventional analysis of G-banded metaphases. 5 out of 6 patients studied at diagnosis showed the t(15;17) translocation. 4 out of 5 patients carrying t(15;17) achieved complete remission and conventional cytogenetic conversion. In 3 cases the whole chromosome painting (WCP) probe 17 discovered one normal chromosome 17 and two fragments indicative of t(15;17) persistence. The FISH-WCP technique seems to be highly sensitive and recommendable in monitoring leukaemias with specific chromosome rearrangements.

Clonal B-cell expansions in peripheral blood of HCV-infected patients

Clonal expansions of IgM-producing B cells were investigated in 38 patients with a chronic hepatitis C virus infection. Eight patients were affected with type II mixed cryoglobulinaemia (two of whom also had non-Hodgkin's lymphoma and one had Waldenström's disease), one with type III mixed cryoglobulinaemia, one with Waldenström's disease, and 28 with chronic liver disease. To detect the clonal B-cell expansions we used a RT/PCR procedure in which the CDR3/FW4 regions of the IgM heavy chain mRNAs were amplified and resolved in sequencing polyacrylamide gels. Clonal Ig gene rearrangements were detected in all patients with type II mixed cryoglobulinaemia and also at a high frequency (24%) in the HCV-infected patients without cryoglobulinaemia. A polyclonal pattern was present in the patient with type III mixed cryoglobulinaemia and in the 15 normal individuals and 16 age-related patients with HCV-negative alcoholic liver disease which were investigated as controls. No association was found between the presence of a clonal B-cell expansion and age, sex, liver histology, or levels of serum aminotransferase. The serum levels of rheumatoid factor were increased in all patients with a clonal expansion, suggesting that the expanded B-cell clones belong to the rheumatoid factor producing B-cell subset.