Detection of B-cell lymphoma in peripheral blood by DNA hybridisation

Monitoring disease in lymphoma and CLL patients using molecular techniques

Over the past decade considerable advances have been made in the sensitivity of detection of residual lymphoma and leukaemia cells. Assays based on the polymerase chain reaction (PCR) can detect one tumour cell in up to 10(5) to 10(6) normal cells. The identification and cloning of breakpoints associated with specific chromosomal translocations has made possible the application of these techniques to a variety of lymphoid malignancies. In parallel, B cell malignancies exhibit rearrangements of their immunoglobulin genes that are also suitable targets for PCR amplification to identify residual cells. Although these techniques provide a useful adjunct to standard methods of detection and diagnosis, their role in determining disease outcome remains investigational. There is confusion as to whether it is necessary to eradicate PCR-detectable lymphoma cells for cure, so it is not yet possible to determine whether the detection of residual lymphoma cells by PCR is an indication to continue therapy.

Minimal residual disease in non-Hodgkin's lymphoma

Recent advances in the sensitivity of detection methods have clearly illustrated that patients in complete clinical remission often harbor residual lymphoma cells that are below the limit of detection using standard staging techniques. However, the clinical significance of this detection is by no means clear. Patients have been identified who remain in very long-term clinical remission despite detection of residual lymphoma cells. In contrast, the eradication of lymphoma is associated with improved outcome in patients undergoing autologous bone marrow transplantation. We review the methodologies for the detection of minimal residual lymphoma and discusses the clinical significance of this detection.

Immunoglobulin light chain restriction and clonal rearrangement in nodular paragranuloma

B-cell clonality was demonstrated in a typical nodular paragranuloma case (NP) by both immunoglobulin (Ig) surface analysis and Ig genes rearrangement studies. On frozen sections, immunostaining for Ig light chain expression revealed a clear-cut predominance of Ig lambda-expressing cells, recognizable as both small lymphocytes and lympho-histiocytic (L&H) cells. Accordingly, molecular analysis of the Ig genes showed a monoclonal rearrangement of the lambda chain gene, although no specific pattern of heavy chain gene rearrangement could be detected by JH analysis. The C lambda rearranged band was identified with two different restriction enzymes, excluding the hypothesis of a genomic polymorphism. Furthermore, the C kappa gene was almost completely deleted, indicating that the developmental hierarchy of Ig genes rearrangement has been respected. The molecular pattern of the C lambda hybridizing band was consistent with monoallelic rearrangement of almost the entire DNA sample, indicating that clonal proliferation was not limited to L&H cells, but also involved surrounding lymphocytes. This finding is in keeping with the immunohistochemical evidence of a lambda light chain restriction on both L&H cells and small lymphocytes, pointing to a close relationship between these two cell types. Our results as a whole suggest that L&H cells and B lymphocytes share a common origin and may both be involved in clonal proliferation in NP.

AL kappa amyloid in a solitary extradural lymphoma

A 68 year old man with a 10 year history of apparently benign IgM kappa paraproteinaemia presented with dysarthria, left hemiparesis, and a sensory peripheral neuropathy. A calcified right temporoparietal extradural mass was shown by scintigraphy with 123I-serum amyloid P component to contain amyloid. There were no extracranial amyloid deposits. Clinical improvement followed craniotomy and partial resection of tissue which consisted of amyloid and a mixed mononuclear cell infiltrate. The amyloid fibrils consisted of the framework 1 region of the variable domain of monoclonal kappa IV immunoglobulin light chains. There was a prominent B-cell clonal immunoglobulin gene rearrangement in the tumour tissue, supporting a diagnosis of lymphoplasmacytic lymphoma, but no sign of systemic lymphoma. Neurological state, tumour volume, and quantity of amyloid have remained static for two years after treatment with chlorambucil.

T-cell receptor beta gene rearrangements in leukaemic B-cells from patients with chronic lymphocytic leukaemia: association with chromosome 6 deletions

Rearrangement of immunoglobulin genes is a characteristic finding in normal B-cells and in leukaemic cells of B-cell origin. In some leukaemic cells simultaneous cross-lineage rearrangement of immunoglobulin- and T-cell receptor (TcR) genes occur. We have analysed TcR beta gene rearrangement in 100 patients with B-cell chronic lymphocytic leukaemia. All samples expressed CD5, CD19 and CD20 and six patients had rearrangements of both immunoglobulin and TcR beta genes. Analysis of gene expression in cells with TcR beta gene rearrangement indicated production of truncated TcR beta transcripts but no expression of the T-cell markers CD3, CD4, CD8, TcR alpha beta or delta on the cell surface. Three of the patients with both Ig and TcR beta rearrangement (50%) were 44 years or younger at diagnosis and cells from three such patients expressed IgG. Three of the six patients had a terminal deletion of the long arm of chromosome 6 with different breakpoints, with or without other chromosomal abnormalities, whereas 6q deletions were found in 4/94 patients without TcR beta gene rearrangement (4.3%) (P = 0.001). This study indicates a correlation between TcR beta gene rearrangement and deletion of chromosome 6q.

Peripheral blood involvement in non-Hodgkin's lymphoma detected by clonal gene rearrangement as a biological prognostic marker

Peripheral blood from 67 patients with non-Hodgkin's lymphoma was examined at initial diagnosis for the presence of circulating lymphoma cells by DNA hybridisation using immunoglobulin and T-cell receptor gene probes. Clonal gene rearrangement was found in 31% (21/67) of patients and correlated with clinical stage, histological grade and bone marrow involvement. Clinical stage and the presence of lymphoma cells in peripheral blood were prognostic factors for progression-free survival in all patients on univariate analysis, but the detection of lymphoma cells was not independent of stage. It was also not a significant predictor for survival. In patients with intermediate- and high-grade lymphoma, the detection of lymphoma cells in peripheral blood was a significant prognostic factor for progression-free survival (PFS) and survival only on univariate analysis. The 3-year PFS was 17% in patients with circulating lymphoma cells compared with 75% if these were absent (P < 0.05). The presence of lymphoma cells in peripheral blood is associated with extensive disease and may be a biological marker of poor disease control. Sensitive techniques of detection should form part of large prospective studies in non-Hodgkin's lymphoma.

Blood lymphocyte clonal excess in advanced non-Hodgkin's lymphoma. Relation to clinical data and prognosis

BACKGROUND

Increasingly sensitive methods, based on the monoclonal nature of NHL, are used to detect tumour spread and remaining disease. Since the lymphomas are thought to arise due to successive genetic changes, clonal cells in different compartments do not necessarily represent the same disease despite a common clonal origin.

PATIENTS AND METHODS

In 179 patients with advanced NHL, clonal cells in peripheral blood were identified by light chain restriction analysed in flow cytometry, i.e. clonal excess (CE) analysis.

RESULTS

CE was more common in low grade NHL (52%) than in high grade NHL (21%). In patients with a normal lymphocyte count CE was found in 23%. CE was significantly correlated to small cell histology and bone marrow involvement. In high grade NHL CE in peripheral blood was more common in those with discordant small or mixed cell involvement of the bone marrow. CE was significantly related to failure to achieve remission in both histologic subgroups. Survival was not influenced by CE in low grade NHL but in high grade NHL. In multivariate analyses however, CE did not emerge as an independent risk factor but age, B-symptoms and LDH were the major factors.

CONCLUSIONS

The utility of blood CE analyses in clinical praxis has still to be settled and the prognostic value of CE per se seem limited in the current perspective. The existence of CE in high grade NHL might be a clue of different biology as compared to de novo high grade NHL.

Non-Hodgkin's lymphomas in children. I. Patterns of disease and classification

Non-Hodgkin's lymphomas (NHL) are part of an overlapping spectrum of lympho-proliferative diseases in childhood. In the first of this 2 part series, the clinicopathological aspects of NHL in childhood are discussed. The rapid progression of disease, the high incidence of micrometastases (over 80%) at diagnosis, and the propensity of hematogenous spread to the bone marrow and the central nervous system (CNS) as well as the clinico-pathologic 'clusters' associated with particular presenting sites distinguish the pediatric forms of disease. Abdominal primary sites most frequently manifest diffuse undifferentiated (Burkitt's or non-Burkitt's) histopathology, B-cell immunophenotype, FAB-L3 cytomorphology and specific karyotypic and/or genotypic alterations of the immuno-globulin genes and the c-myc oncogene. Mediastinal presentation is associated with lymphoblastic histopathology, T-cell immunophenotype and a variety of less consistent karyotypic and genotypic aberrations. Ki-1 lymphoma, a rare subtype of large cell NHL with specific features is often of T cell origin. The requirements for diagnosis, staging and monitoring are presented in the context of the associations between clinico-pathological presentation and subsequent behavior. The most frequent sites of disease progression and relapse are involvement of the bone marrow and the CNS. For Burkitt's lymphoma there is a historic perspective and a description of particular epidemiologic, clinical, virologic, immunophenotypic and genotypic features. Cytogenetic and molecular biologic studies of genomic rearrangements are advancing the understanding of oncogenesis, clonality, lineage, and clinical behavior. The capacity to detect and amplify DNA from submicroscopic disease may contribute to prognostic stratification both at diagnosis and during subsequent monitoring.

Use of the Polymerase Chain Reaction for the Detection of Tumor Cell Involvement of Bone Marrow and Peripheral Blood: Implications for Purging

Bone marrow purging is being performed increasingly in an effort to deplete residual tumor cells from the graft prior to reinfusion. Several studies have suggested that the removal of tumor cells is an important clinical goal. In this review the utility of the polymerase chain reaction (PCR) for the detection of small numbers of tumor cells in bone marrow and peripheral blood is discussed. Using sensitive assays such as PCR, it is expected that the efficacy of bone marrow purging strategies will be improved and this will hopefully result in decreased relapse rates following autologous bone marrow transplantation.

Incidence and prognostic significance of blood lymphocyte clonal excess in localized non-Hodgkin's lymphoma

Despite elaborate staging procedures, a substantial number of patients with localized NHL experience dissemination after local therapy, indicating that current routine methods are insufficient to detect tumour spread. We have used flow cytometric clonal excess (CE) analysis of peripheral blood in conjunction with routine staging procedures to study the occurrence of occult leukaemic spread in patients with localized NHL stages I, IE and IIE. CE in peripheral blood was a rare finding, identified in only 11% (14/130), and slightly more frequent in low-grade NHL, 20% compared to high-grade NHL, 7%. There was no correlation to any of the other major prognostic factors studied. Occult tumour spread would suggest an increased risk of relapse and possibly a decreased survival after local therapy. Among 93 patients given only local treatment there was an increased risk of relapse in those with low-grade malignant lymphomas and CE, which was not found in patients with high-grade malignant lymphomas and CE. CE in peripheral blood had no influence on survival in either of the histologic groups. A tentative explanation is that circulating lymphoma cells represent indolent populations irrespective of the histology of the primary tumour. The malignant nature of such a lymphoma spread might not be obvious during this rather limited follow-up of a median 34 months. The clinical interpretation is that the existence of CE in peripheral blood in patients with localized high-grade NHL should have no influence on the choice of therapy. In localized low-grade lymphoma the same therapeutic attitude which applies to widespread disease might be considered.

Rapid, nonradioactive detection of clonal T-cell receptor gene rearrangements in lymphoid neoplasms

Southern blot hybridization analysis of clonal antigen receptor gene rearrangements has proved to be a valuable adjunct to conventional methods for diagnosing lymphoid neoplasia. However, Southern blot analysis suffers from a number of technical disadvantages, including the time necessary to obtain results, the use of radioactivity, and the susceptibility of the method to various artifacts. We have investigated an alternative approach for assessing the clonality of antigen receptor gene rearrangements in lymphoid tissue biopsy specimens. This approach involves the amplification of rearranged gamma T-cell receptor genes by the polymerase chain reaction and analysis of the polymerase chain reaction products by denaturing gradient gel electrophoresis. By use of this approach, clonal rearrangements from neoplastic lymphocytes constituting as little as 0.1-1% of the total cells in the tissue are detected as discrete bands in the denaturing gel after the gel is stained with ethidium bromide and viewed under ultraviolet light. In contrast, polyclonal rearrangements from reactive lymphocytes appear as a diffuse smear along the length of the gel. Our findings suggest that polymerase chain reaction combined with denaturing gradient gel electrophoresis may offer a rapid, nonradioactive, and sensitive alternative to Southern blot analysis for the diagnostic evaluation of lymphoid tissue biopsy specimens.

Immunogenetic analysis of bone marrow aspirates in patients with non-Hodgkin lymphomas

The immunogenetic analysis (IGA) on the staging bone marrow aspirates in 15 patients with non-Hodgkin lymphoma (NHL) is reported. We found the sensitivity of IGA and morphologic examination in detecting bone marrow involvement by malignant lymphoma to be 91% and 82%, respectively. In 11 cases there was agreement between the morphologic findings and IGA. In 8 of these 11 cases, IGA confirmed the morphologic involvement of the bone marrow by demonstrating clonal rearrangement of either the immunoglobulin heavy- and/or light-chain or the T-cell receptor beta chain (TCR) genes. In 3 of these 11 cases, morphology showed no involvement and IGA showed germline configurations for both the immunoglobulin heavy- and light-chain or the TCR genes. In 2 additional cases the techniques proved to be complementary, as involvement was detected by only 1 of the 2 procedures. In 1 of these 2 cases, IGA showed gene rearrangement while morphologic examination was negative for involvement by NHL, while in the other case, morphologic examination showed involvement by NHL, but IGA did not show gene rearrangement. IGA was also useful in determining the clonality of solitary lymphoid nodules in the 2 remaining cases when morphologic interpretation was equivocal. In the 12 cases with bone marrow involvement, the immunophenotype and immunogenotype agreed in 11 cases. In the one case in which there was a discordance between the immunophenotype and immunogenotype, the immunophenotype was incorrectly interpreted as B-cell lineage, while the immunogenotype demonstrated a T-cell lineage. IGA also demonstrated a clonal population in 1 case of T-chronic lymphocytic leukemia where other techniques could not demonstrate the clonality of the pathologic process. IGA analysis may detect bone marrow involvement in NHL which may not be detected by morphologic examination because of patchy distribution.

Detection of specific DNA sequences by fluorescence amplification: a color complementation assay

We have developed a color complementation assay that allows rapid screening of specific genomic DNA sequences. It is based on the simultaneous amplification of two or more DNA segments with fluorescent oligonucleotide primers such that the generation of a color, or combination of colors, can be visualized and used for diagnosis. Color complementation assay obviates the need for gel electrophoresis and has been applied to the detection of a large and small gene deletion, a chromosomal translocation, an infectious agent, and a single-base substitution. DNA amplification with fluorescent oligonucleotide primers has also been used to multiplex and discriminate five different amplified DNA loci simultaneously. Each primer set is conjugated to a different dye, and the fluorescence of each dye respective to its amplified DNA locus is scored on a fluorometer. This method is valuable for DNA diagnostics of genetic, acquired, and infectious diseases, as well as in DNA forensics. It also lends itself to complete automation.

Immunoglobulin heavy-chain gene rearrangement in peripheral blood mononuclear cells in non-Hodgkin's lymphomas--correlation with kappa:lambda analysis and clinical features

41 patients with non-Hodgkin's lymphomas were analysed to determine occurrence of B-cell monoclonality in peripheral blood mononuclear cells using two different methods: determination of kappa:lambda ratio by light microscopic immunofluorescence, and heavy-chain gene rearrangement by DNA-technique. In 21 patients (51%) clonal heavy-chain rearrangement was found in blood, whilst 18 of the patients (44%) showed and abnormal kappa:lambda ratio. Discordant results between the methods were observed in 5 cases. Clones with gene rearrangements suggesting blood involvement were found in 16/25 (64%) patients with low grade lymphomas, in 5/16 (31%) patients with high grade lymphoma, in 17/21 (81%) patients with bone marrow involvement, in 20/27 (74%) of stage III-IV lymphomas and in all of the 14 patients with a high lymphocyte count (greater than or equal to 5.0 X 10(9]. The conclusion was that clonal analysis by the DNA-technique is a more sensitive method than the kappa:lambda determination using immunofluorescence. Even though the method is time-consuming, it could prove to be valuable in selected cases.

Clonal antigen receptor gene rearrangements and Epstein-Barr viral DNA in tissues of Hodgkin's disease

In an initial survey of 16 cases of Hodgkin's disease, tissues from one case of nodular sclerosing Hodgkin's disease, a recurrence with numerous Reed-Sternberg cells, demonstrated faint heavy- and light-chain immunoglobulin gene rearrangements. Analysis of seven additional similar cases with extremely numerous Reed-Sternberg cells revealed that six of these seven cases contained clonally rearranged heavy- or light-chain genes. In addition, the original biopsy specimen from the index case (obtained two years prior to the recurrence) had the same pattern of rearrangements of the immunoglobulin genes. In contrast, a germline configuration was observed for the beta T cell receptor gene in all cases. These cases of Hodgkin's disease were also investigated for the presence of Epstein-Barr viral (EBV) genomes by Southern and slot-blot DNA hybridization analysis. Tissues from four of the 21 case studied showed evidence of EBV DNA sequences. Uninvolved lymphoid tissue from two of the positive cases failed to demonstrate viral DNA. To assess clonality of the cells containing the EBV genomes, the tissues positive for EBV DNA were also hybridized with a restriction fragment probe for the terminal sequences of the EBV genome. By this analysis three of the four cases demonstrated a clonal population of EBV-infected cells.

Thermostable DNA polymerase chain amplification of t(14;18) chromosome breakpoints and detection of minimal residual disease

Achieving the capacity to detect minimal numbers of neoplastic cells is a major cancer diagnostic challenge. Chromosomal translocations such as the t(14;18)(q32;q21) found in follicular and some nonfollicular lymphomas provide a tumor-specific molecular marker. The 14;18 breakpoints are focused at one of six immunoglobulin heavy chain joining (JH) regions on chromosome 14 and a small major breakpoint region (MBR) of the BCL2 gene on chromosome 18. We utilized universal oligonucleotide primers of a region 5' to the BCL2 MBR and at the 3' end of JH segments to initiate a DNA polymerase chain reaction that amplified these BCL2-JH junctures. Use of thermostable DNA polymerase enabled annealing and synthesis steps at temperatures approaching the melting point of the primers, providing a sensitive and specific assay capable of detecting 1 lymphoma cell in 10(6) normal cells. This technique identified the subclinical presence of leukemic cells in all seven patients examined, including two in clinical remission. It also assessed the effectiveness of protocols designed to purge malignant cells from marrow. Moreover, this approach enabled the rapid DNA sequencing of chromosomal breakpoints without their molecular cloning. This assay markedly refines the capacity to detect minimal residual disease and should improve the ability to determine the stage of disease, stratify treatment, and evaluate therapy.

The non-Hodgkin's lymphomas: pathology, staging, treatment

The non-Hodgkin's lymphomas include a broad range of neoplasms derived from the T cells and B cells and their precursors in the lymphoid system. Although they are not among the most common cancers, the lymphomas have engendered a great deal of interest among researchers because of their interesting biology and responsiveness to therapy. The non-Hodgkin's lymphomas include at least ten major subtypes of diseases with different morphologic characteristics and clinical behavior. Based upon survival characteristics, it is convenient to divide the lymphomas into three broad categories, low grade, intermediate grade, and high grade. The low grade lymphomas usually arise in middle age or older individuals (median age, 55 years). They are derived from B cells and often have a follicular architectural pattern. They usually present with advanced stages of disease, often by virtue of bone marrow involvement. Nevertheless, patients are usually asymptomatic and may even have spontaneous regressions of disease. These lymphomas are responsive to a broad range of therapies including irradiation, single agent or multi-agent chemotherapy, or combined modality therapy. They are also affected by treatment with biologicals such as alpha interferon and monoclonal antibodies. Unfortunately, response to any of these therapies is often transient and relapse is common. The intermediate grade lymphomas include the common large cell lymphomas (follicular or diffuse) and diffuse mixed cell lymphoma. The lymphomas, together with the high grade immunoblastic lymphoma, are often grouped together for the development of management strategies. These lymphomas may be derived from B cells or T cells. They occur over a broader age range than the low grade lymphomas and they are much more aggressive in their natural behavior. Effective treatment programs have been developed for both limited and advanced clinical stages of disease. In limited disease, moderately intensive chemotherapy is often combined with involved field irradiation. In advanced stage disease, more aggressive combination chemotherapy programs are usually employed. From 40% to 80% of patients may be cured with these approaches, depending upon the initial extent of disease. Two types of high grade lymphoma-lymphoblastic and small noncleaved cell are particularly aggressive in their behavior. Lymphoblastic lymphoma is a T cell lymphoma that often arises in adolescent males and presents with a large mediastinal mass, marrow, and CNS involvement. It closely resembles acute lymphoblastic leukemia (ALL) and similarly intensive chemotherapy programs as are utilized in ALL may be successful in its management.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunoglobulin gene rearrangement in immunoproliferative small intestinal disease (IPSID)

Analysis of DNA from the mucosal tissue of three patients with immunoproliferative small intestinal disease (IPSID) and alpha chain disease, two of whom had early stage disease responsive to antibiotics, showed monoclonal heavy and light chain gene rearrangements in all cases. These findings suggest that IPSID is neoplastic even in its early stages, but that the neoplastic cells respond to normal stimuli. Monoclonal lymphoid populations could not be detected in circulating lymphocytes from these patients, which raises the possibility that the circulatory pathways of lymphocytes derived from human gut associated lymphoid tissue may not necessarily parallel those in experimental animals.

Circulating lymphoma cells in patients with B & T non-Hodgkin's lymphoma detected by immunoglobulin and T-cell receptor gene rearrangement

We studied peripheral blood mononuclear cells from 50 patients with active B- and T-cell non-Hodgkin's lymphoma by DNA hybridisation. Nineteen patients (38%) had circulating clones of cells detected by immunoglobulin gene rearrangement (17 patients) or T-cell receptor gene rearrangement (2 patients) with JH and J beta 2 probes. Lymphoma tissue and peripheral blood were studied simultaneously in 22 patients, 9 of which had a circulating clone of cells in peripheral blood. In 7 patients the gene rearrangement in lymphoma tissue and peripheral blood mononuclear cells was identical. However, in 2 patients both heavy chain and light chain gene rearrangements were different in tissue and peripheral blood. The incidence of peripheral blood involvement was commonest in advanced CSIII & IV disease (54%) compared to CSI & II disease (18%) (P less than 0.05), and in low grade (45%) compared to intermediate and high grade lymphoma (31%) (difference not statistically significant). Only 4 patients had definite lymphoma cells seen on peripheral blood smear. The presence of circulating lymphoma cells correlated with conventional assessment of bone marrow involvement although circulating clones were detected in 30% (12/40) of patients with apparently normal bone marrow.

Prolonged disease-free survival after autologous bone marrow transplantation in patients with non-Hodgkin's lymphoma with a poor prognosis

Despite advances in the primary treatment of non-Hodgkin's lymphoma, relapse is common and treatment after relapse is unsatisfactory. Autologous bone marrow transplantation, although sometimes successful, has generally had disappointing results. We conducted a trial of such transplantation in patients with relapsed non-Hodgkin's lymphoma, using strict criteria in selecting patients; we included only those in whom disease was minimal after conventional treatment (nodal disease less than 2 cm and bone marrow involvement less than or equal to 5 percent on histologic examination) and whose tumor cells expressed the B1 antigen. Forty-nine patients meeting these criteria received cyclophosphamide and whole-body irradiation supported by transplantation of autologous bone marrow that had been treated in vitro with anti-B1 monoclonal antibody and complement. All patients had features of a poor prognosis, including relapse from primary chemotherapy, histologic conversion to more aggressive disease, and extra-nodal dissemination. Thirty-three patients had a history of bone marrow involvement--16 at the time that marrow was obtained. Hematologic and immunologic engraftment was achieved in all patients. Only two treatment-related deaths occurred, from venoocclusive disease of the liver and intracerebral hemorrhage, respectively. Disease-free remission without maintenance therapy has lasted from greater than 2 to greater than 52 months in 34 patients (median follow-up, greater than 11 months). These results are similar to those obtained in patients with advanced, high-grade non-Hodgkin's lymphoma treated with primary combination chemotherapy. This study demonstrates that autologous bone marrow transplantation has tolerable toxicity and high efficacy in a subset of patients who are otherwise incurable but still responsive to cytoreductive therapy. The results suggest a role for such transplantation in the treatment of selected patients with newly diagnosed non-Hodgkin's lymphoma.

Diagnostic use of immunoglobulin and T-cell receptor gene rearrangements in lymphoproliferative disease

Gene rearrangements of immunoglobulin and T cell antigen receptor gene loci were studied in 67 patients referred to a general hematology clinic. The results of gene analysis supported the clinical diagnosis in most cases where involved tissue was studied. However, in a number of cases, gene rearrangement studies gave unexpected results of possible diagnostic significance. Thus two patients who presented diagnostic difficulties were finally diagnosed as having non-Hodgkin's lymphoma; gene analysis suggested that the initial diagnosis of Hodgkin's disease may have been correct. In two patients who had chronic lymphocytosis and were suspected of having chronic lymphocytic leukemia, no evidence of monoclonal disease of B or T cells could be found and the basis for the lymphocytosis was presumed to be non-malignant. Gene analysis was able to detect monoclonal B cell disease in the otherwise normal blood of two of six patients with lymphoma, one of two patients with macroglobulinemia, and none of six patients with myeloma. The study of gene rearrangements may be practical aid to diagnosis in some situations of uncertainty.

Immunoglobulin gene rearrangements in Hodgkin's disease

An initial survey of biopsy specimens from 16 cases of Hodgkin's disease revealed clonal immunoglobulin gene rearrangements in one specimen, which contained large numbers of Reed-Sternberg (R-S) cells. As a result of this finding, the configuration of immunoglobulin and T-cell receptor gene DNA was investigated in biopsy tissues from other cases that were histologically and immunophenotypically consistent with Hodgkin's disease and contained numerous R-S cells. In six of seven such specimens (all of the nodular sclerosing subtype), selected solely on the basis of high R-S cell content and sufficient frozen tissue for study, at least one immunoglobulin gene was found to be rearranged in a clonal manner. Additionally, tissue samples obtained at two different time points from the original patient who showed immunoglobulin gene rearrangements revealed identical patterns of rearrangement. In the majority of cases, only a single gene showed rearrangement, and the rearranged bands in Southern blot autoradiograms were usually considerably less intense than the germline bands. No rearrangements of T-cell receptor DNA were detected in any case with a probe for the beta T-cell receptor gene. The results suggest that clonal cell populations possessing uniform immunoglobulin gene rearrangements are present in tissue in some cases of Hodgkin's disease. It is not possible to determine which cells contain these rearranged genes, but the increased incidence of detectable rearrangements in cases with high numbers of R-S cell raises the possibility that immunoglobulin gene rearrangement occurs in these cells.