Isolation of viable Hodgkin and Reed-Sternberg cells from Hodgkin disease tissues

A new approach to the study of Hodgkin lymphoma by flow cytometry

Hodgkin lymphoma (HL) appears to originate from germinal centre B cells but lacks expression of most B cell markers. In contrast to non-Hodgkin B lymphomas, HL is not routinely diagnosed using flow cytometry techniques, and diagnosis is mainly based on immunohistochemical and cytomorphological pathology studies. Hodgkin and Reed-Sternberg cells are large and fragile, making them difficult to study by flow cytometry. The aim of this study was to characterise the CD71 expression pattern on CD4+ T cells from HL patients and to design a simple flow cytometry algorithm to complement the histopathological diagnosis of HL. The present study suggests the utility of a conventional staining protocol with a simple panel of seven markers (CD15, CD30, CD4, CD8, CD71, CD3, and CD45) and a well-defined analysis strategy. The proposed algorithm uses the CD71 ratio (calculated as the percentage of CD71+ CD4+ T cells divided by the percentage of CD71+ CD45+ CD3- lymphocytes), with a cut-off of 0.5 to establish diagnosis groups as suggestive (≥0.5) or not suggestive (<0.5) of HL. In HL, CD71 expression is higher on CD4+ T lymphocytes than on non-T lymphocytes. In addition, the CD4+ T cell population is increased in HL patients, with no change in amounts of CD8+ T cells. Application of the CD71 ratio algorithm yielded a sensitivity of 82% and specificity of 87%, with 84.61% of patients correctly diagnosed. Although histopathology remains the gold standard for definitive HL diagnosis, the proposed flow cytometry method provides a rapid method to guide the study that would allow a more robust and integrated diagnosis. Moreover, the procedure is easily applicable in most clinical laboratories as it does not require state-of-the-art cytometers and uses standard reagents.

Role of Flow Cytometric Immunophenotyping for Classic Hodgkin Lymphoma in Small Biopsy and Cytology Specimens

CONTEXT.—

The diagnosis of classic Hodgkin lymphoma (CHL) traditionally requires surgical tissue biopsy because of the paucity of diagnostic Hodgkin and Reed-Sternberg cells. Diagnosis can be challenging in small core needle and cytologic biopsies, which are increasingly used because of reduced costs and minimal invasiveness. Flow cytometric (FC) identification of Hodgkin and Reed-Sternberg cells is possible, but FC test efficacy is not well studied outside of validation settings, especially in small specimens.

OBJECTIVE.—

To assess the testing efficacy of FC performed on small biopsy and cytology specimens for the diagnosis of CHL.

DESIGN.—

We reviewed 131 patients with CHL and 459 patients without CHL during a 3-year period who underwent a small biopsy procedure, including core biopsy and/or cytology evaluation, with concurrent routine clinical FC testing for CHL, assessing performance of FC in small specimens.

RESULTS.—

Evaluating testing efficacy, sensitivity was 95.4% and specificity was 98.2%, whereas positive and negative predictive values were 92.2% and 99.0%, respectively. Although there were more false-positive results than compared with published validation studies, expert review identified distinct diagnostic pitfalls; awareness of these may improve testing efficacy.

CONCLUSIONS.—

Although FC diagnosis of CHL was historically considered unfeasible, our findings in a real-world clinical setting suggest that FC adds diagnostic value to small biopsy evaluation, reducing time to treatment, costs, and invasive excisional procedures.

A Basic Approach to Lymph Node and Flow Cytometry Fine-Needle Cytology

According to the World Health Organization (WHO), the new classification of lymphomas is mainly based on morphological, immunophenotypical, and molecular criteria. Consequently, this new approach has led from the substantial role that architecture played in the past to a secondary panel highlighting the role of fine-needle biopsy (FNB). Applied together with other ancillary techniques, such as flow cytometry (FC), FNB is a potential tool for the diagnosis of lymphomas, and enlarged lymph nodes represent an excellent target for the implementation of this technique. Despite the difficulties inherent in this technology, which might pose problems in differential diagnosis, in the majority of cases this joint work allows an accurate diagnosis of malignancy and even correct subcharacterization in routine lymphomas. Additionally, in selected cases, other molecular techniques like FISH and PCR can also be performed on FNB specimens, helping in the characterization and diagnosis of lymphomas. In this review, we discuss the basic aspects of the combination of FNB cytology and FC in the diagnosis and subclassification of lymphomas. The preanalytical phase is extensively discussed. The advantages, disadvantages, and technical limitations of this joint work are addressed in general and in terms of the accurate subclassification of lymphomas.

Microfluidics for the detection of minimal residual disease in acute myeloid leukemia patients using circulating leukemic cells selected from blood

We report a highly sensitive microfluidic assay to detect minimal residual disease (MRD) in patients with acute myeloid leukemia (AML) that samples peripheral blood to search for circulating leukemic cells (CLCs). Antibodies immobilized within three separate microfluidic devices affinity-selected CLC subpopulations directly from peripheral blood without requiring pre-processing. The microfluidic devices targeted CD33, CD34, and CD117 cell surface antigens commonly expressed by AML leukemic cells so that each subpopulation's CLC numbers could be tracked to determine the onset of relapse. Staining against aberrant markers (e.g. CD7, CD56) identified low levels (11-2684 mL(-1)) of CLCs. The commonly used platforms for the detection of MRD for AML patients are multi-parameter flow cytometry (MFC), typically from highly invasive bone marrow biopsies, or PCR from blood samples, which is limited to <50% of AML patients. In contrast, the microfluidic assay is a highly sensitive blood test that permits frequent sampling for >90% of all AML patients using the markers selected for this study (selection markers CD33, CD34, CD117 and aberrant markers such as CD7 and CD56). We present data from AML patients after stem cell transplant (SCT) therapy using our assay. We observed high agreement of the microfluidic assay with therapeutic treatment and overall outcome. We could detect MRD at an earlier stage compared to both MFC and PCR directly from peripheral blood, obviating the need for a painful bone marrow biopsy. Using the microfluidic assay, we detected MRD 28 days following one patient's SCT and the onset of relapse at day 57, while PCR from a bone marrow biopsy did not detect MRD until day 85 for the same patient. Earlier detection of MRD in AML post-SCT enabled by peripheral blood sampling using the microfluidic assay we report herein can influence curative clinical decisions for AML patients.

Flow cytometric detection of the classical hodgkin lymphoma: clinical and research applications

Classical Hodgkin lymphoma (CHL) is a relatively uncommon B cell-derived neoplasm that presents with rare malignant cells in an abundant reactive background. The diagnosis of CHL currently relies on a combination of morphologic findings and immunohistochemical stains. With the exception of rare cases with dramatically increased malignant populations, isolation of pure viable tumor cells has not been historically possible. Recently, a reliable flow cytometric assay for direct detection and isolation of the malignant cells in this disease has been developed. This assay has proven useful diagnostically and has been clinically validated to have a very high sensitivity and nearly absolute specificity for the diagnosis of CHL in routine clinical samples. This paper describes the methodology for the flow cytometric detection of CHL in clinical samples as well as current state of evaluation of background lymphocytes as an adjunct diagnostic test. Also discussed are exciting research applications of the direct isolation of viable tumor cells in CHL. The current state of flow cytometric evaluation of nodular lymphocyte predominant Hodgkin lymphoma and T cell-rich large B cell lymphoma is also briefly discussed.

Circulating clonotypic B cells in classic Hodgkin lymphoma

Although Hodgkin and Reed-Sternberg (HRS) cells are B lymphoid cells, they are unlike any normal cells of that lineage. Moreover, the limited proliferative potential of HRS cells belies the clinical aggressiveness of Hodgkin lymphoma (HL). More than 20 years ago, the L428 HL cell line was reported to contain a small population of phenotypic B cells that appeared responsible for the continued generation of HRS cells. This observation, however, has never been corroborated, and such clonotypic B cells have never been documented in HL patients. We found that both the L428 and KM-H2 HL cell lines contained rare B-cell subpopulations responsible for the generation and maintenance of the predominant HRS cell population. The B cells within the HL cell lines expressed immunoglobulin light chain, the memory B-cell antigen CD27, and the stem cell marker aldehyde dehydrogenase (ALDH). Clonal CD27(+)ALDH(high) B cells, sharing immunoglobulin gene rearrangements with lymph node HRS cells, were also detected in the blood of most newly diagnosed HL patients regardless of stage. Although the clinical significance of circulating clonotypic B cells in HL remains unclear, these data suggest they may be the initiating cells for HL.

Lack of evidence of disease contamination in ovarian tissue harvested for cryopreservation from patients with Hodgkin lymphoma and analysis of factors predictive of oocyte yield

Ovarian cryopreservation is a promising technique to preserve fertility in women with Hodgkin lymphoma (HL) treated with chemotherapy. Thus, the aim of this study was to examine harvested ovarian tissue for subclinical involvement by HL by morphology/immunohistochemistry, and to define patient and treatment factors predictive of oocyte yield. This was a retrospective analysis of 26 ovarian tissue samples harvested for cryopreservation from women with HL. Histology, immunohistochemistry and follicle density (number mm⁻³) was examined. Disease status and preharvest chemotherapy details were obtained on 24 patients. The median age was 22 years (range 13–29). Seven of 24 patients had infradiaphragmatic disease at time of harvest. Nine of 20 patients had received chemotherapy preharvest (ABVD (Adriamycin®, Bleomycin, Vinblastine and Dacarbazine)=7, other regimens=2). The seven receiving ABVD showed no difference in follicle density compared to patients not receiving treatment (n=14); (median=1555 vs 1620 mm³P=0.97). Follicle density measurement showed no correlation with patient age (R²=0.0001, P=0.99). There was no evidence of HL involvement in the 26 samples examined (95% CI=0–11%). In conclusion, subclinical involvement of HL has not been identified in ovarian tissue, even when patients have infradiaphragmatic disease. Furthermore, the quality of tissue harvested does not appear to be adversely affected by patient's age or prior ABVD chemotherapy.

Survival and clonal expansion of mutating "forbidden" (immunoglobulin receptor-deficient) epstein-barr virus-infected b cells in angioimmunoblastic t cell lymphoma

Angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) is a peculiar T cell lymphoma, as expanding B cell clones are often present besides the malignant T cell clones. In addition, large numbers of Epstein-Barr virus (EBV)-infected B cells are frequently observed. To analyze the differentiation status and clonal composition of EBV-harboring B cells in AILD, single EBV-infected cells were micromanipulated from lymph nodes of six patients with frequent EBV(+) cells and their rearranged immunoglobulin (Ig) genes analyzed. Most EBV-infected B cells carried mutated Ig genes, indicating that in AILD, EBV preferentially resides in memory and/or germinal center B cells. EBV(+) B cell clones observed in all six cases ranged from small polyclonal to large monoclonal expansions and often showed ongoing somatic hypermutation while EBV(-) B cells showed little tendency for clonal expansion. Surprisingly, many members of expanding B cell clones had acquired destructive mutations in originally functional V gene rearrangements and showed an unfavorable high load of replacement mutations in the framework regions, indicating that they accumulated mutations over repeated rounds of mutation and division while not being selected through their antigen receptor. This sustained selection-free accumulation of somatic mutations is unique to AILD. Moreover, the survival and clonal expansion of "forbidden" (i.e., Ig-deficient) B cells has not been observed before in vivo and thus represents a novel type of viral latency in the B cell compartment. It is likely the interplay between the microenvironment in AILD lymph nodes and the viral transformation that leads to the survival and clonal expansion of Ig-less B cells.

Molecular morphology of Hodgkin lymphoma

No other disease entity has provided greater impetus for the development of the concept of "molecular morphology" than Hodgkin lymphoma. Efforts to understand the etiology of this enigmatic disease have stimulated the application and refinement of almost every mode of biomedical scientific exploration. Notwithstanding the vast amount of data generated, much is still unknown about this remarkable disease, serving as an ongoing inducement to the development and application of new technologies for the analysis of cells and molecules in a morphologic environment.

STAT3 is constitutively activated in Hodgkin cell lines

Hodgkin disease (HD) represents a malignant lymphoma in which the putative malignant Hodgkin and Reed-Sternberg cells are rare and surrounded by abundant reactive nonmalignant cells. It has been suggested that cytokines such as interleukin-6 (IL-6) are involved in the pathogenesis of the disease. The expression of the IL-6 receptor (IL-6R) complex and its link to the activation of signal transducers and activators of transcription (STAT) molecules in HD cell lines was investigated. Gel retardation and Western blot analyses revealed a high level of constitutively activated STAT3 in 5 of 7 HD cell lines, which could not be detected in Burkitt lymphoma cell lines. Different levels of IL-6R protein were measured in various HD cell lines: L428 and Dev cells were characterized by very low levels of gp80 and gp130, on KMH2 cells only gp130 but no gp80 was detected, whereas L540, L591, HDLM2, and L1236 were positive for both gp80 and gp130, suggesting a possible autocrine stimulation of STAT3. However, a further increase in STAT3 activation on IL-6 or IL-6/soluble IL-6R stimulation was not observed. Neutralizing monoclonal antibodies against IL-6, gp80, gp130, or both receptor subunits did not affect the proliferation or the constitutive activation of STAT molecules in HD cell lines. However, the tyrosine kinase inhibitor AG490 blocked the constitutive activation of STAT3 and inhibited spontaneous growth of HD tumor cells. The evidence suggests abnormal STAT signaling and growth regulation in Hodgkin cell lines. (Blood. 2001;98:762-770)

Class switch recombination was specifically targeted to immunoglobulin (Ig)G4 or IgA in Hodgkin's disease-derived cell lines

In T cell-dependent immune responses, class switch recombination occurs in germinal centres. There is now evidence that Hodgkin/Reed-Sternberg cells are derived from germinal centre B cells. Cytokines specifically determine the direction of class switching, i.e the isotype of the new antibodies. We performed restriction analyses and polymerase chain reaction on the immunoglobulin heavy chain loci for five Hodgkin's disease-derived B-cell lines and one Hodgkin's disease-derived T-cell line in order to analyse class switch recombination. In all the B-cell lines, class switch recombination had been targeted to Calpha4 or Calpha1/2. This showed that cell-line precursors had undergone class switching, probably under the influence of TH2 or TH3 cell-derived cytokines. Deletions comprising several constant region genes were observed in cell lines L428, L1236, L591 and KMH2. Karyotype analyses of two of these revealed translocational breakpoints within the immunoglobulin heavy chain gene locus. Our data support the view that a chromosomal instability may occur during class switch recombination in Hodgkin/Reed-Sternberg cells causing chromosomal breaks. Thus, as in other germinal centre B cell-derived lymphomas, the immunoglobulin gene locus may be frequently involved in structural chromosomal aberrations in Hodgkin's disease.

Molecular single-cell analysis of Hodgkin- and Reed-Sternberg cells harboring unmutated immunoglobulin variable region genes

Hodgkin- and Reed-Sternberg (H/RS) cells in classical Hodgkin's disease of the B lineage are the clonal progeny of antigen-experienced B cells harboring highly mutated immunoglobulin variable (V) region genes. Based on the detection of obviously destructive somatic mutations in a fraction of cases, we speculated that H/RS cells may be derived from a pre-apoptotic germinal center B cell. Seemingly contradicting this speculation, we present here the first case of classical Hodgkin's disease with H/RS cells harboring unmutated, potentially functional V region genes, which may indicate the derivation of the H/RS clone from a naive B cell. However, germinal center founder cells, which have not yet acquired somatic mutations, already have the intrinsic propensity to die by apoptosis. Thus, the rare occurrence of H/RS cells with unmutated V genes is expected if the H/RS cells are derived from the pool of pre-apoptotic germinal center B cells.

Molecular single-cell analysis of the clonal relationship of small Epstein-Barr virus–infected cells and Epstein-Barr virus–harboring Hodgkin and Reed/Sternberg cells in Hodgkin disease

Epstein-Barr virus (EBV) can be detected in the tumor cells of approximately 40% of cases of classical Hodgkin disease (cHD). Clonality studies suggest that infection of the neoplastic Hodgkin and Reed/Sternberg (HRS) cells occurs before tumor clone expansion. In EBV-positive cases, variable numbers of EBER-positive small B cells are sometimes also observed that immunohistologically differ from the neoplastic cells by lack of CD30 and latent membrane protein 1 expression. To analyze the clonal relationship between these EBV+ cells and the HRS cells, single EBV-infected CD30− B cells, as well as HRS cells from 3 cases of EBV-positive cHD were micromanipulated, their immunoglobulin gene rearrangements amplified and then compared with each other. In 2 cases, all small EBV-infected cells were clonally unrelated to the HRS cells. In a third case, 2 of 29 small CD30− cells were found to carry HRS cell-specific rearrangements. Thus, small CD30−EBV-infected B cells in cHD belong to the HRS tumor clone rarely, if at all. In all cases, small clones unrelated to the HRS cell clones were identified among the small EBV+ CD30− cells. The vast majority of small EBV+ CD30− B cells was found to carry somatically mutated V region genes, indicating that in lymph nodes of patients with HD, like in the peripheral blood of healthy individuals, EBV persists in memory B cells.

Molecular single-cell analysis of the clonal relationship of small Epstein-Barr virus–infected cells and Epstein-Barr virus–harboring Hodgkin and Reed/Sternberg cells in Hodgkin disease

Epstein-Barr virus (EBV) can be detected in the tumor cells of approximately 40% of cases of classical Hodgkin disease (cHD). Clonality studies suggest that infection of the neoplastic Hodgkin and Reed/Sternberg (HRS) cells occurs before tumor clone expansion. In EBV-positive cases, variable numbers of EBER-positive small B cells are sometimes also observed that immunohistologically differ from the neoplastic cells by lack of CD30 and latent membrane protein 1 expression. To analyze the clonal relationship between these EBV+ cells and the HRS cells, single EBV-infected CD30− B cells, as well as HRS cells from 3 cases of EBV-positive cHD were micromanipulated, their immunoglobulin gene rearrangements amplified and then compared with each other. In 2 cases, all small EBV-infected cells were clonally unrelated to the HRS cells. In a third case, 2 of 29 small CD30− cells were found to carry HRS cell-specific rearrangements. Thus, small CD30−EBV-infected B cells in cHD belong to the HRS tumor clone rarely, if at all. In all cases, small clones unrelated to the HRS cell clones were identified among the small EBV+ CD30− cells. The vast majority of small EBV+ CD30− B cells was found to carry somatically mutated V region genes, indicating that in lymph nodes of patients with HD, like in the peripheral blood of healthy individuals, EBV persists in memory B cells.

Rare occurrence of classical Hodgkin's disease as a T cell lymphoma

Recent work identified Hodgkin and Reed-Sternberg (H/RS) cells in classical Hodgkin's disease (cHD) as clonal progeny of mature B cells. Therefore, it is generally assumed that cHD homogenously represents a B cell lymphoma. In a subset of cHD, however, H/RS cells expressing T cell-associated proteins may be candidates for alternative lineage derivation. Single H/RS cells with cytotoxic T cell phenotype were micromanipulated from three cases of cHD and analyzed by single cell polymerase chain reaction for immunoglobulin heavy (IgH) and light chain (IgL) gene rearrangements, T cell receptor (TCR)-beta gene rearrangements, and germline configuration of the IgH and TCR-beta loci. H/RS cells from two cases of cHD harbored clonal, somatically mutated Ig gene rearrangements, whereas TCR-beta loci were in germline configuration. In contrast, H/RS cells from an additional case harbored clonal TCR-beta variable/diversity/joining (VDJ) and DJ gene rearrangements, whereas the IgH locus was in germline configuration on both alleles. Thus, in two cases of cHD with H/RS cells expressing cytotoxic T cell molecules, the tumor cells are derived from mature B cells that aberrantly express T cell markers. In a third case, however, H/RS cells were derived from a T cell, demonstrating that cHD can also occur as a T cell lymphoma.

Mutation of the p53 Gene Is Not a Typical Feature of Hodgkin and Reed-Sternberg Cells in Hodgkin’s Disease

Point mutations of the p53 tumor suppressor gene are a frequent finding in human carcinomas and are thought to be an important oncogenic event. In non-Hodgkin lymphomas, p53 mutations occur in a minor fraction of cases. However, conclusive data are still lacking for Hodgkin’s disease (HD) where the analysis meets technical problems. The neoplastic tumor cell clone in HD is represented by the large Hodgkin and Reed-Sternberg (HRS) cells, which account for only a minority of all cells in the tumor tissue (often <1%). To identify putative HRS cell-specific mutations, single HRS cells were micromanipulated from frozen tissue sections of HD biopsy specimens. Exons 4 to 8 of the p53 gene (in which more than 90% of p53 mutations associated with human neoplasms occur) were amplified from these single cells and sequenced. Mutations of p53 were not found in HRS cells of any of 8 cases of HD analyzed. We conclude that mutation of the p53 gene is only rarely, if at all, involved in the pathogenesis of HD.

Mutation of the p53 Gene Is Not a Typical Feature of Hodgkin and Reed-Sternberg Cells in Hodgkin’s Disease

Point mutations of the p53 tumor suppressor gene are a frequent finding in human carcinomas and are thought to be an important oncogenic event. In non-Hodgkin lymphomas, p53 mutations occur in a minor fraction of cases. However, conclusive data are still lacking for Hodgkin’s disease (HD) where the analysis meets technical problems. The neoplastic tumor cell clone in HD is represented by the large Hodgkin and Reed-Sternberg (HRS) cells, which account for only a minority of all cells in the tumor tissue (often &lt;1%). To identify putative HRS cell-specific mutations, single HRS cells were micromanipulated from frozen tissue sections of HD biopsy specimens. Exons 4 to 8 of the p53 gene (in which more than 90% of p53 mutations associated with human neoplasms occur) were amplified from these single cells and sequenced. Mutations of p53 were not found in HRS cells of any of 8 cases of HD analyzed. We conclude that mutation of the p53 gene is only rarely, if at all, involved in the pathogenesis of HD.

Identification of common germinal-center B-cell precursors in two patients with both Hodgkin's disease and non-Hodgkin's lymphoma

BACKGROUND

Hodgkin's disease and non-Hodgkin's B-cell lymphoma occasionally occur in the same patient. The identification of a common precursor of the two types of lymphoma would show definitively that Reed-Sternberg cells originate from B cells.

METHODS

We studied lymphomas from two patients, one with a composite lymphoma (classic Hodgkin's disease and a follicular lymphoma in the same lymph node) and the other with a T-cell-rich B-cell lymphoma that was followed by classic Hodgkin's disease. Single Reed-Sternberg cells and non-Hodgkin's lymphoma cells from frozen sections were micromanipulated. The rearranged immunoglobulin variable-region genes (V genes) of the heavy and light chains were amplified by the polymerase chain reaction from genomic DNA and sequenced.

RESULTS

In both patients, the Reed-Sternberg cells were related clonally to the non-Hodgkin's lymphoma B cells. The V genes carried somatic mutations (a hallmark of germinal-center B cells and their descendants). In both patients, some somatic mutations were shared by the Reed-Sternberg and non-Hodgkin's lymphoma cells, whereas other somatic mutations were found exclusively in one or the other cell type.

CONCLUSIONS

In two patients with classic Hodgkin's disease and non-Hodgkin's B-cell lymphoma, we identified a common B-cell precursor, probably a germinal-center B-cell, for both lymphomas. This finding suggests that the two types of lymphoma underwent both shared and distinct transforming events and provides proof of the B-cell derivation of Reed-Sternberg cells in classic Hodgkin's disease.

Clonality and germinal centre B-cell derivation of Hodgkin/Reed-Sternberg cells in Hodgkin's disease

Molecular single-cell studies of Hodgkin and Reed-Sternberg (HRS) cells in Hodgkin's disease (HD) have revealed the clonal nature of these peculiar tumour cells. HRS cells in classical HD as well as lymphocyte predominant (LP) HD originate from germinal center (GC) B cells in most cases, if not all. Whereas HRS cells in LP HD represent transformed antigen-selected GC B cells with evidence of ongoing immunoglobulin (Ig) V gene mutation, HRS cells in classical HD appear to often or always derive from GC B cells that have lost the capacity to express a functional antigen receptor. Using Ig gene rearrangements amplified from HRS cells as clonal markers for the tumour cells, it could be shown that the same HRS cell clone can disseminate in the patient and persist throughout the course of the disease. A common derivation of the tumour cells was recently demonstrated in two cases representing combinations of HD and non-Hodgkin's lymphoma. Finally, V-gene analysis showed that viable cells enriched by magnetic cell sorting from HD patients as HRS cells indeed represent the HRS-cell population of the patient.