Rosetting and other reactions of the Reed-Sternberg cell

Mapping the Spatial Dynamics of the CD4+ T Cell Spectrum in Classical Hodgkin Lymphoma

As around 25% to 30% of classical Hodgkin lymphoma (cHL) patients with advanced stages do not respond to standard therapies, the tumor microenvironment of cHL is one avenue that may be explored with the aim of improving risk stratification. CD4+ T cells are thought to be one of the main cell types in the tumor microenvironment. However, few immune signatures have been studied, and many of these lack related spatial data. Thus, our aim is to spatially resolve the CD4+ T cell subtypes that influence cHL outcome, depicting new immune signatures or transcriptional patterns that are in crosstalk with the tumor cells. This study was conducted using the NanoString GeoMx digital spatial profiling technology, based on the selection of distinct functional areas of patients' tissues followed by gene-expression profiling. The goals were to assess the differences in CD4+ T cell populations between tumor-rich and immune-predominant areas defined by different CD30 and PD-L1 expression levels and seek correlations with clinical metadata. Our results depict a complex map of CD4+ T cells with different functions and differentiation states that are enriched at distinct locations, the flux of cytokines and chemokines that could be related to these, and the specific relationships with the clinical outcome.

A Review of the Flow Cytometric Findings in Classic Hodgkin Lymphoma, Nodular Lymphocyte Predominant Hodgkin Lymphoma and T Cell/Histiocyte-Rich Large B Cell Lymphoma

Classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, and T cell/histiocyte-rich large B cell lymphoma form a unique set of lymphomas with similar morphologic growth patterns (occasional neoplastic cells within a prominent cellular cell background) that are pathobiologically related. Distinguishing these entities has been historically difficult by flow cytometry; however, our laboratory has developed antibody-fluorochrome combinations capable of immunophenotyping these lymphomas. Additionally, characterization of the background reactive lymphocytes can aid in narrowing the differential diagnosis. This review summarizes the immunophenotypic features and insights of the neoplastic and reactive populations found in this unique group of lymphomas.

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.

CD4+ T cells in classical Hodgkin lymphoma express exhaustion associated transcription factors TOX and TOX2

In classical Hodgkin lymphoma (cHL), the highly abundant CD4+ T cells in the vicinity of tumor cells are considered essential for tumor cell survival, but are ill-defined. Although they are activated, they consistently lack expression of activation marker CD26. In this study, we compared sorted CD4+CD26- and CD4+CD26+ T cells from cHL lymph node cell suspensions by RNA sequencing and T cell receptor variable gene segment usage analysis. This revealed that although CD4+CD26- T cells are antigen experienced, they have not clonally expanded. This may well be explained by the expression of exhaustion associated transcription factors TOX and TOX2, immune checkpoints PDCD1 and CD200, and chemokine CXCL13, which were amongst the 100 significantly enriched genes in comparison with the CD4+CD26+ T cells. Findings were validated in single-cell RNA sequencing data from an independent cohort. Interestingly, immunohistochemistry revealed predominant and high frequency of staining for TOX and TOX2 in the T cells attached to the tumor cells. In conclusion, the dominant CD4+CD26- T cell population in cHL is antigen experienced, polyclonal, and exhausted. This population is likely a main contributor to the very high response rates to immune checkpoint inhibitors in cHL.

A comparison and review of the flow cytometric findings in classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, T cell/histiocyte rich large B cell lymphoma, and primary mediastinal large B cell lymphoma

The "Hodgkin-like" lymphomas including classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, T cell/histiocyte rich large B cell lymphoma, and primary mediastinal large B cell lymphoma have been shown to be pathobiologically related. With the exception of primary mediastinal large B cell lymphoma, these lymphomas have similar morphologic growth patterns with occasional neoplastic cells within a prominent reactive cell background. Historically, distinguishing these entities was difficult by flow cytometry; however, over the past 15 years, our laboratory has developed antibody-fluorochrome combinations capable of accurately distinguishing these entities by their immunoprofile. Additionally, an algorithmic approach based on characterization of the background reactive B-cell and T-cell populations can aid in narrowing the differential diagnosis. This review summarizes both the morphologic and immunophenotypic features and the current flow cytometric insights of the neoplastic and reactive populations found in this unique subset of lymphomas.

Immune Microenvironment Features and Dynamics in Hodgkin Lymphoma

Simple Summary

As happens in all neoplasms, the many reciprocal interactions taking place between neoplastic cells and the other reactive cells impact the course of the disease. Hodgkin Lymphoma is an haematologic malignancy where most of the pathological tissue is indeed composed by reactive cells and few neoplastic cells. Consequently, it represents an interesting subject for the description of the neoplastic and non-neoplastic cells interaction. In this review we report and discuss the more recent findings of microenvironmental studies about this disease.

Abstract

Classical Hodgkin’s lymphoma (cHL) accounts for 10% of all lymphoma diagnosis. The peculiar feature of the disease is the presence of large multinucleated Reed–Sternberg and mononuclear Hodgkin cells interspersed with a reactive microenvironment (ME). Due to the production of a large number of cytokines, Hodgkin cells (HCs) and Hodgkin Reed–Sternberg cells (HRSCs) attract and favour the expansion of different immune cell populations, modifying their functional status in order to receive prosurvival stimuli and to turn off the antitumour immune response. To this purpose HRSCs shape a biological niche by organizing the spatial distribution of cells in the ME. This review will highlight the contribution of the ME in the pathogenesis and prognosis of cHL and its role as a possible therapeutic target.

Rosetting T cells in Hodgkin lymphoma are activated by immunological synapse components HLA class II and CD58

A unique feature of Hodgkin lymphoma (HL) is the presence of CD4+ T cells that surround, protect, and promote survival of tumor cells. The adhesion molecules involved in this so-called T-cell rosetting are important components of the immunological synapse (IS). However, it is unknown whether this synapse is fully assembled and leads to T-cell activation by enabling interaction between the T-cell receptor (TCR) and human leukocyte antigen class II (HLA-II). We established a novel rosetting model by coculturing HLA-II-matched peripheral blood mononuclear cells with HL cell lines and showed IS formation with activation of rosetting T cells. HLA-II downregulation by class II transactivator knockout did not affect the extent of rosetting, but almost completely abrogated T-cell activation. Intriguingly, the level of CD58 expression correlated with the extent of rosette formation, and CD58 knockout or CD2 blockade reduced both rosette formation and T-cell activation. The extension of our findings to primary HL tissue by immunohistochemistry and proximity ligation assays showed interaction of CD2 with CD58 and of TCR-associated CD4 with HLA-II. In conclusion, T-cell rosetting in HL is established by formation of the IS, and activation of rosetting T cells critically depends on the interaction of both TCR-HLA-II and CD2-CD58.

Flow Cytometry for Non-Hodgkin and Hodgkin Lymphomas

Multiparametric flow cytometry is a powerful diagnostic tool that permits rapid assessment of cellular antigen expression to quickly provide immunophenotypic information suitable for disease classification. This chapter describes a general approach for the identification of abnormal lymphoid populations by flow cytometry, including B, T, NK, and Hodgkin lymphoma cells suitable for the clinical and research environment. Knowledge of the common patterns of antigen expression of normal lymphoid cells is critical to permit identification of abnormal populations at disease presentation and for minimal residual disease assessment. We highlight an overview of procedures for processing and immunophenotyping non-Hodgkin B- and T-cell lymphomas and also describe our strategy for the sensitive and specific diagnosis of classical Hodgkin lymphoma and nodular lymphocyte predominant Hodgkin lymphoma.

Characterization and Purification of Neoplastic Cells of Nodular Lymphocyte Predominant Hodgkin Lymphoma from Lymph Nodes by Flow Cytometry and Flow Cytometric Cell Sorting

We report the flow cytometric (FC) identification and characterization of lymphocyte predominant (LP) cells from tissues involved by nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). First, we immunophenotyped the NLPHL cell line (DEV) confirming a germinal center immunophenotype, lack of expression of CD32 and CD58, and expression of CD54. Nineteen of 26 lymph nodes involved by NLPHL demonstrated a population with an LP immunophenotype (73%), which included expression of germinal center markers (CD75/Bcl-6-positive, CD32-weak/negative without CD10), a B-cell immunophenotype (CD19/CD20/CD40⁺), IgD and/or IgM expression (67%), and lack of programmed death-ligand 1/ligand 2. The LP cells demonstrated an adhesion macromolecule expression pattern distinct from Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma (CHL) (uniform CD50 and variable CD58 for NLPHL; minimal CD50, bright CD58 expression for CHL). A two-tube consensus assay identified LP cells in all seven NLPHL cases examined and only one non-NLPHL case (94 cases evaluated). Finally, FC cell sorting studies confirm that FC-defined populations have an LP cytomorphology. Taken together, these findings demonstrate a two-tube consensus assay can be used to immunophenotype NLHPL with high specificity and sensitivity and rapidly purify LP cells for genetic studies. This study also confirms aneuploidy in LP cells, provides antigens that may be helpful in distinguishing NLPHL from CHL, and suggests that T cells interact less avidly with LP cells than with Hodgkin and Reed-Sternberg cells.

The immune microenvironment in Hodgkin lymphoma: T cells, B cells, and immune checkpoints

Classical Hodgkin lymphoma is curable in the majority of cases with chemotherapy and/or radiation. However, 15-20% of patients ultimately relapse and succumb to their disease. Pathologically, classical Hodgkin lymphoma is characterized by rare tumor-initiating Reed-Sternberg cells surrounded by a dense immune microenvironment. However, the role of the immune microenvironment, particularly T and B cells, in either promoting or restricting Classical Hodgkin lymphoma growth remains undefined. Recent dramatic clinical responses seen using monoclonal antibodies against PD-1, a cell surface receptor whose primary function is to restrict T cell activation, have reignited questions regarding the function of the adaptive immune system in classical Hodgkin lymphoma. This review summarizes what is known regarding T cells, B cells, and immune checkpoints in classical Hodgkin lymphoma.

A six-color flow cytometry assay for immunophenotyping classical Hodgkin lymphoma in lymph nodes

OBJECTIVES

We have recently demonstrated that classical Hodgkin lymphoma (CHL) can be immunophenotyped by flow cytometry (FC), thus obviating the need for immunohistochemistry in many cases. The previously described nine-color assay, however, cannot be used by laboratories that do not have access to a nine- or ten-color flow cytometer. Therefore, a six-color FC tube was designed employing the following combination: CD64-FITC/CD30-PE/CD40-PeCy5.5/CD20-PECy7/CD95-APC/CD3-APC-H7.

METHODS

To validate this assay, we analyzed 408 tissue specimens (including 55 CHL cases, 26 of which had been previously cryopreserved). Specimen inclusion criteria included the identification of an abnormal population by FC or (if no abnormal population was identified) greater than 50,000 viable events and specimen age less than 4 days. All FC studies were examined blinded to any clinical, laboratory, or histologic information.

RESULTS

The diagnostic sensitivity and specificity of the six-color FC assay was 85.4% and 99.7%, respectively.

CONCLUSIONS

Taken together, these results suggest that the six-color FC assay has acceptable sensitivity and specificity for clinical use, allowing more FC laboratories to immunophenotype CHL by this method.

Flow cytometry for non-Hodgkin and classical Hodgkin lymphoma

Multiparametric flow cytometry is a powerful diagnostic tool that permits rapid assessment of cellular antigen expression to quickly provide immunophenotypic information suitable for disease classification. This chapter describes a general approach for the identification of abnormal lymphoid populations by flow cytometry, including B, T, and Hodgkin lymphoma cells suitable for the clinical and research environment. Knowledge of the common patterns of antigen expression of normal lymphoid cells is critical to permit identification of abnormal populations at disease presentation and for minimal residual disease assessment. We highlight an overview of procedures for processing and immunophenotyping non-Hodgkin B- and T-cell lymphomas and also describe our strategy for the sensitive and specific diagnosis of classical Hodgkin lymphoma.

Strategies for immunophenotyping and purifying classical Hodgkin lymphoma cells from lymph nodes by flow cytometry and flow cytometric cell sorting

Flow cytometry is an established technique to immunophenotype hematopoietic neoplasms. While the diagnosis of classical Hodgkin lymphoma (CHL) has commonly been made using paraffin sections, we have recently demonstrated that the neoplastic Hodgkin and Reed-Sternberg (HRS) cells of CHL can be identified by flow cytometry. Using 6- and 9-color flow cytometric assays, CHL can be immunophenotyped with 85-90% sensitivity and nearly 100% specificity. Analysis of this data requires using established gating strategies to help in the identification of putative HRS cell populations. Interestingly, HRS cells bind to reactive T cells (HRS-T cell rosetting) and this phenomenon can be identified and utilized diagnostically by flow cytometry. In addition, the reactive T cells of CHL show characteristic immunophenotypic changes by flow cytometry and these changes can suggest a diagnosis of CHL. Finally, these principles can be employed to rapidly purify HRS cells using flow cytometric cell sorting. This manuscript provides experimental protocols for immunophenotyping CHL by flow cytometry as well as purifying the HRS cells via flow cytometric cell sorting.

Flow cytometry can diagnose classical hodgkin lymphoma in lymph nodes with high sensitivity and specificity

The diagnosis of classical Hodgkin lymphoma (CHL) has been made in tissue sections as attempts to identify neoplastic Hodgkin and Reed Sternberg (HRS) cells in lymph nodes by flow cytometry (FC) have been unsuccessful. However, we have recently demonstrated that HRS cells can be identified by FC, often present as T-cell-HRS-cell rosettes. In this study, we examined the usefulness of a novel 9-color (CD95-Pacific blue/CD64-fluorescein isothiocyanate/CD30-phycoerythrin [PE]/CD45-PE-Texas red/CD40-PE cyanine [Cy]5.5/CD20-PECy7/CD15-allophycocyanin [APC]/CD71-APC-AlexaFluor A700/CD5-APC-Cy7), single tube FC assay to diagnose CHL in lymph nodes. We used the FC assay to determine diagnostic sensitivity and specificity in 279 blindly identified and 141 selected (for specimen type or cytopreparation morphologic features suggesting CHL) tissues. Of the 53 morphologically defined CHL cases identified (10 in the unselected group; 43 in the selected group), the FC assay diagnostic sensitivity and specificity were 88.7% and 100%, respectively. With the current availability of 8 (or more) color clinical flow cytometers, this assay can now be applied to routinely immunophenotype and confirm a diagnosis of CHL or as an adjunct to immunohistochemical analysis.

Amplification of TCRbeta gene rearrangements from micromanipulated single cells: T cells rosetting around Hodgkin and Reed-Sternberg cells in Hodgkin's disease are polyclonal

Despite accounting for only a minor fraction of all cells in Hodgkin's lymphoma tissue, the Hodgkin and Reed-Sternberg (HRS) cells represent the malignant tumor cell clone in Hodgkin's disease (HD). By far the most abundant cell type in the tumor tissue are CD4+ T cells. Some of them intimately associate with HRS cells forming rosettes around them. This study addresses the question whether the rosetting phenomenon reflects a specific interaction between T and HRS cells by asking whether the rosettes are composed of T cells expressing a restricted TCR repertoire. Single rosetting T cells were micromanipulated from frozen sections of tumor tissue in two cases of nodular sclerosing HD and one case of lymphocyte predominant HD. TCR Vbeta gene rearrangements were amplified from these single cells by PCR. Of 83 potentially functional Vbeta gene rearrangements obtained altogether from the three cases, 81 were found to be clonally unrelated. Furthermore, they did not show signs of selection of the receptor chains for recognition of common epitopes: The usage of Vbeta and Jbeta gene segments as well as the distribution of complementarity-determining region (CDR) 3 lengths was similar to what was seen in a collection of 60 Vbeta gene rearrangements from blood of healthy donors and no recurrent CDR3 amino acid motifs were found. These data suggest that the HRS cells attract CD4+ T cells nonspecifically.

Hodgkin's disease: a disorder of dysregulated cellular cross-talk

Hodgkin's disease (HD) is a peculiar type of human malignant lymphoma characterized by a very low frequency of tumor cells, the so called Hodgkin and Reed-Sternberg (H-RS) cells, embedded in a hyperplastic background of non-neoplastic (reactive) cells recruited and activated by H-RS cells-derived cytokines. H-RS cells can be functionally regarded as antigen-presenting cells (APC) able to elicit an intense, but anergic and ineffective, T-cell mediated immune response along with a hyperplastic inflammatory reaction which involves several cell types including T- and B-cells, neutrophils, eosinophils, plasma cells, fibroblasts and stromal cells. In tissues involved by HD, malignant H-RS cells and their reactive neighboring cells are able to cross-talk via a complex network of cytokine- and cell contact-dependent interactions. As a result of such interactions, mediated by specific surface receptors and adhesion molecules on both tumor and non-neoplastic cells, H-RS cells may receive several proliferative and anti-apoptotic signals favoring the cellular expansion and tumor cell survival in HD. The ineffective T-cell immune response elicited by the abnormal APC function of H-RS cells may further contribute to the biologic and clinical progression of HD. Innovative therapeutic strategies aimed at blocking the pathways of dysregulated cellular cross-talk among H-RS cells and bystander reactive cell populations might be beneficial in the treatment of HD patients.

Hodgkin's cells express CD83, a dendritic cell lineage associated antigen

Hodgkin's cells (HC) are considered to be the malignant cells of Hodgkin's disease (HD), but despite extensive studies, no conclusive evidence has emerged regarding their non-malignant counterpart and the ontogeny of these cells remains controversial. The analysis of a possible dendritic cell (DC) origin of HC has been hampered to date by the lack of a DC lineage specific marker. The expression of the two DC-associated antigens CD83 and CMRF-44, the B lymphocyte restricted molecule CD79, and the costimulator molecule CD86, was examined in lymph nodes from 23 HD patients using immunohistological techniques. The majority of HC expressed the CD83 (22/23) and CD86 antigens (20/23), whereas expression of the CMRF-44 antigen was variable (10/23) and usually only a subpopulation of HC stained. In contrast, the CD79 antigen was absent from most HC (17/23). The presence of the CD83 antigen on HC in the absence of the CD79 antigen supports a possible DC lineage origin for some HC. Regardless of its role in lineage assignment, CD83 may become a useful immunohistological marker for HD as the CD83 antigen was present on most HC.

The antigen-presenting cell function of Reed-Sternberg cells

Reed-Sternberg cells, the neoplastic cells of Hodgkin's disease, express all membrane molecules required to function as antigen-presenting cells (APCs), such as major histocompatibility complex (MHC) class II antigens and the recently characterized B7 proteins, which are of critical importance for APC to adequately stimulate CD4+ T cells. As APC do, Reed-Sternberg cells also express the adhesion molecules ICAM-1 (CD54) and LFA-3 (CD58), via which T cells are able to adhere to the cell. MHC antigens, B7 proteins as well as the adhesion molecules are expressed by Reed-Sternberg cells in virtually all cases of Hodgkin's disease, irrespective of the subtype. In vitro studies have shown that Hodgkin's disease-derived cell lines are potent stimulators of mixed lymphocyte cultures and that the MHC antigens, B7 proteins and the adhesion molecules, expressed by Hodgkin's disease-derived cell lines, are essential for such a function. Taken together, these data strongly suggest that Reed-Sternberg cells function as APC in vivo, and that the APC function of the cell is a major common denominator of Hodgkin's disease. The APC function of Reed-Sternberg cells does not support the hypothesis that they derive from dendritic cells, since activated B and T cells may also exert an APC function. Analysis of the antigens that are potentially expressed by Reed-Sternberg cells may greatly advance our knowledge on the pathogenesis of Hodgkin's disease and may allow the development of immunotherapy as an alternative treatment method.

Reciprocal/dichotomic expression of vimentin and B cell differentiation antigens in Reed-Sternberg's cells

An immunohistochemical study of 63 cases of Hodgkin's disease was undertaken using formalin-fixed paraffin embedded tissue sections. The antibodies used were against L26, LN-1, LN-2, EMA (epithelial membrane antigen), Leu-M1, Vimentin, UCHL-1, S-100, and lysozyme. Hodgkin's disease could be divided into three groups: the first group was LN-1+/L26+/vimentin-, the second LN-1-/L26+/vimentin+, and the third LN-1-/L26-/vimentin+). Sixteen cases of follicular lymphomas were also examined and were all positive for LN-1 and L26 and negative for vimentin. Thus the vimentin negativity of the first group, including 7 nodular lymphocyte-predominant cases, gives further evidence of their germinal center B-cell origin. Since vimentin is expressed mainly in the immature stage of B-lymphocytes, the second group of Hodgkin's disease may represent immature B-cell Hodgkin's disease. In the third group, vimentin was present in Reed-Sternberg's (RS) and Hodgkin's (H) cells in 45 of the 48 cases (92.5%). In none of 48 cases were these cells positive for S-100 or lysozyme, but strong vimentin-positivity still suggested monocytic or histiocytic origin. The results of our study suggest, at least, divergent origin of RS's and H's cells.

Production of granulopoiesis-stimulating and -inhibiting activities by T cells associated with malignant cells in lymphomas

The possible role of T lymphocytes in the formation of granulomatous reactions seen in certain malignant lymphoid tumours was investigated by measuring the granulopoietic colony-stimulating activity (CSA) and granulopoietic-inhibiting activity (IA) produced by stimulated T-lymphocytes isolated from peripheral blood, spleen and lymph nodes of patients and normal subjects. Lymph-node T-cells from patients with benign lymphoid hyperplasia, B-cell non-Hodgkin's lymphoma (B-NHL), and non-granulomatous Hodgkin's disease (HD) showed no CSA, but the cells produced IA of 40 +/- 23%, 40 +/- 24% and 50.5 +/- 22.5% respectively. The corresponding cells from patients with HD accompanied by granulomatous reactions produced CSA of 6.85 +/- 6.5 u/microliters and IA of 23.5 +/- 21%. The presence of a granulomatous reaction in malignant lymphoma was correlated with the stimulation of granulopoiesis in vitro by T lymphocytes associated with malignant cells. A correlation was demonstrated between neutrophilic and eosinophilic colonies obtained in vitro under the influence of CSA-producing T cells isolated from malignant lymphomas and the neutrophils and eosinophils present in the granuloma. These results showed that tumour-infiltrating T cells play a role in the presence of granulomatous reactions seen in lymphomas. Peripheral-blood T cells from healthy subjects, and from patients with B-NHL, or with HD unaccompanied by granulocytic reactions produced CSAs of, respectively, 5 +/- 0.5 u/microliter, 4.8 +/- 2.2 u/microliters and 5.3 +/- 0.4 u/microliters, and IAs of 45 +/- 18%. 50 +/- 5.5% and 50.5 +/- 7% respectively. The corresponding values for HD patients with granulocytic reactions were CSA. 17 +/- 15.5 u/microliters, and IA, 9.5 +/- 9%. No correlation was demonstrated between neutrophilic colonies obtained in vitro under the influence of HD blood T cells and neutrophils present in blood. Only one correlation was found: between the percentage of eosinophilic colonies and the number of blood eosinophils. HD blood T cells did not seem to explain completely granulocytic reactions seen in blood.

The Reed-Sternberg cell/lymphocyte rosette. I. Properties of rosettes formed between Hodgkin's cell lines and allogeneic lymphocytes

The properties of rosettes formed between the Hodgkin's cell lines, L428 and L591, and allogeneic peripheral blood mononuclear cell populations have been investigated. Immunocytochemical analysis showed that the majority of adherent cells were T-cells of both the CD4 and CD8 subsets. Only relatively few B-cells and monocytes were seen to adhere. However, when peripheral blood mononuclear cell populations were fractionated, it was found that monocytes were as good as T-cells at forming rosettes with both L428 and L591, though B-cells were shown to be poor at forming such associations. Treatment of both L428 and L591 with neuraminidase resulted in a significant reduction (P less than 0.01) in the mean number of adherent lymphocytes and in the numbers of Hodgkin's tumour cells which formed rosettes. Smaller, less significant effects were observed for Cytochalasin B and trypsin. EDTA (10(-2) M) at pH 7.2 had no significant effect on rosetting for L428 or L591. Adherence of allogeneic lymphocytes to L428 or L591 was pH dependent but did not appear to correlate with cell surface charge. Treatment of L428 cells with Fab fragments prepared from the IgG fraction of a hyperimmune rabbit anti-L428 antiserum, significantly (P less than 0.05) inhibited the adherence of allogeneic lymphocytes, but only when used at high concentration. The binding requirements of the Hodgkin's cell lines with allogeneic peripheral blood lymphocytes, as described in this study, appear to be quite different from those described for freshly isolated Hodgkin's tumour cells with autologous intratumoral lymphocytes. This suggests that the two phenomena may be unrelated. There would appear to be an absolute requirement for cell surface sialic acid for allogeneic lymphocyte attachment to the HD cell lines. This might suggest that the receptor-ligand system involved contains sialic acid as an integral part of the cell surface receptor structure involved in recognition of the appropriate ligand.

Expression of lymphoid-associated antigens on Hodgkin's and Reed-Sternberg cells of Hodgkin's disease. An immunocytochemical study on lymph node cytospins using monoclonal antibodies

The aim of this study was to elucidate the origin of Hodgkin's and Reed-Sternberg cells. Lymph node cytospins and frozen sections from 20 cases of Hodgkin's disease of different histological subtypes were immunostained by the immuno-alkaline phosphatase technique using a panel of monoclonal antibodies. As expected, the Hodgkin's and Reed-Sternberg cells of all cases were positive for the CD30 (Ki-1), CD15 (hapten X) and CD25 (Tac) antigens. In eight cases, a variable percentage of typical Hodgkin's and Reed-Sternberg cells showed a clear-cut cytoplasmic and/or surface positivity for the T-cell-associated antigens CD3, CD5, CD6 and CD4 (seven cases) or CD8 (one case), but consistently lacked B-cell and macrophage-associated markers. The best visualization of T-cell antigens was obtained in cytocentrifuge preparations and in areas of lymph node frozen sections that had been infiltrated by clusters of Hodgkin's and Reed-Sternberg cells. In two cases of Hodgkin's disease (nodular sclerosis, mixed cellularity) the neoplastic cells weakly expressed the B-cell antigens CD19 and CD22, but not T-cell or macrophage-associated markers. In 10 cases, Hodgkin's and Reed-Sternberg cells were negative for all the lymphoid- and macrophage-associated antigens. These results suggest a lymphoid (either T or B) rather than histiocytic origin for the Hodgkin's and Reed-Sternberg cells in a number of Hodgkin's disease cases.

Hodgkin disease: malignancy, inflammation and abnormal immunity

The effect of Hodgkin disease cells on the surrounding environment is complex. In the light of recent findings on growth factors and oncogenes a hypothesis on Hodgkin disease is presented. The interrelation of three main features of Hodgkin disease: malignancy, inflammation and abnormal immunity may be explained by the local secretion of platelet-derived growth factor like substances and interleukin-1 like substances by malignant Hodgkin disease cells.

Immunoblastic sarcoma of T- and B-cell types: morphologic description and comparison

Immunoblastic sarcoma (IBS) is a large cell lymphoma conceptually related to transformed T and B lymphocytes of the extrafollicular compartment of the immune system (immunoblasts). This light microscopic study of a series of 47 immunologically defined cases of IBS was undertaken in an attempt to define more precisely the morphologic features of the T- and B-cell subtypes. A remarkable morphologic spectrum characterized T-IBS (31 cases), which could be divided into two main groups: 1) tumors composed of varying mixtures of small, medium-sized, and large transformed cells; and 2) tumors with more homogeneous populations of medium-sized or large transformed cells. These cells, in all sizes, generally had abundant pale-staining cytoplasm, delicate nuclear membranes, finely dispersed chromatin, and one to several, small or medium-sized, prominent nucleoli. A distinctive background of small, irregular lymphocytes was frequently present. Plasmacytoid differentiation, seen most consistently as amphophilic staining of the cytoplasm, generally characterized B-IBS (16 cases). B-IBS similarly showed a morphologic spectrum that occurred in two main forms: 1) tumors consisting of a spectrum of transformed cells, with the smaller cells often showing the most striking plasmacytoid differentiation; and 2) tumors consisting predominantly of medium-sized to large transformed cells with varying degrees of plasmacytoid differentiation. With this constellation of features, all but two cases of T-IBS and one case of B-IBS were morphologically distinguishable.

Reed-Sternberg/lymphocyte rosette: lymphocyte subpopulations as defined by monoclonal antibodies

The Reed-Sternberg cell/lymphocyte rosette characteristic of Hodgkin's disease tissue and cell suspensions was investigated with monoclonal antibodies on fresh viable cell suspensions prepared from nine cases of Hodgkin's disease. The biopsy material comprised six spleens and three lymph nodes. The majority of the rosetting lymphocytes were T cells, primarily of the helper subset. Some of the attached lymphocytes were suppressor T cells. In addition, a few of the rosetting lymphocytes around Reed-Sternberg cells were B cells.

Characteristics of Sternberg-Reed, and related cells in Hodgkin's disease: an immunohistological study

A panel of monoclonal antileucocyte antibodies was used in a study of Hodgkin's disease (HD) to explore the phenotypic characteristics of Sternberg-Reed and related cells (collectively termed HD cells). Cryostat preparations of 31 lymph nodes and 2 spleens were obtained from 30 patients with active HD. The histological diagnoses were: lymphocyte predominance (LP), 4 patients; nodular sclerosis (NS), 22; mixed cellularity (MC), 2; lymphocyte depletion (LD), 2. The monoclonal antibodies used were: OKT3, T11, Leu-1 (pan T cell specific); Leu-3A (T "helper" specific); Leu-2A, OKT8 (T "suppressor" specific); immunoglobulin (Ig) antibodies: anti kappa and lambda light chains, anti mu and delta heavy chains; B1 (anti B lymphocyte); CA2-11 (anti HLA-DR); OKM1, Mo-2 (anti myeloid/monocyte); OKT9 (anti transferrin receptor); Leu-7 (anti "NK" cell) and J5 (anti common ALL antigen). Reactions with peanut lectin (PNL) were also studied. The reactions were developed using a modified "ABC" immunoperoxidase technique. Specific attention was paid to the cell surface phenotype and anatomical localisation of HD cells in relation to surrounding T and B lymphocytes. HD cells formed distinct "rosettes" with T cells of "helper" phenotype although in 3 cases (1: LP, 2: NS) Leu-7 positive cells formed a prominent component of these interactions. In partially involved lymph node and spleen, HD cells were prominently distributed in a perifollicular distribution. In addition follicular mantle zones were frequently infiltrated by HD cells, the degree of ensuing destruction being related to the extent of lymph node effacement by HD. In 2 cases (1: NS, 1: LD) HD cells expressed clear, positive reactions with B1 although in neither of these cases nor in any other instance, was surface Ig expressed on the HD cell surface. The great majority of HD cells reacted positively with both OKT9 and, as previously reported, with anti HLA-DR antibody. In addition, HD cells demonstrated intense surface and cytoplasmic staining with PNL. HD cells were negative with all other antibodies. On the basis of these findings, no lineage specificity can confidently be attributed to the HD cell. However, the pattern of immunohistological reactions suggest that it is related to a cell of B follicular origins.

Immunologic characterization of Reed-Sternberg cells and other cell components in lymph nodes with Hodgkin's disease

Seven lymph nodes from patients with Hodgkin's disease were immunologically studied. Histologically these cases consisted of 3 lymphocyte predominance, 2 mixed cellularity, and 2 nodular sclerosis. Positive staining of mononuclear Hodgkin- and multinuclear Reed-Sternberg (RS) cells were obtained with anti-Ia like antigens and OKT9 (anti-transferrin receptor) monoclonal antibodies. No supportive data for discussing similarity of RS cells with ordinary histiocytes, B-lymphocytes or T-lymphocytes were obtained from the study of surface phenotype, although some analogy was present with histiocytes. Small lymphocytes around RS cells were helper/inducer T-lymphocytes, and the relationship between these T lymphocytes and RS cells was discussed.

An immunohistological study of the cellular constituents of Hodgkin's disease using a monoclonal antibody panel

Cryostat sections of lymphoid tissue from 44 cases of Hodgkin's disease were analysed by immunoperoxidase staining using a panel of monoclonal antibodies which included reagents reactive with T cells and their subsets, B cells, HLA-DR, Ig, dendritic reticulum cells and C3b receptor. A wide spectrum of immunohistological patterns was observed ranging from cases in which T cells were numerous (B cells being absent or present in only small numbers) to cases in which very prominent B cell follicles were present. These follicles contained a meshwork of dendritic reticulum cells and were composed of polyclonal B cells (as assessed by light chain expression). T cells were present in small numbers within these B cell follicles, often clustered in a thin rim around individual Reed-Sternberg and Hodgkin's cells. All B cell-rich cases were examples of lymphocyte predominant Hodgkin's disease. Assessment of the T cell helper/suppressor ratios was hindered by the fact that both anti-helper antibodies (OKT4 and anti-Leu 3a) reacted with macrophages. However the majority of cases appeared to contain a normal excess of T helper cells. HLA-DR was strongly expressed in T cell rich areas, on Reed-Sternberg and Hodgkin's cells, on vascular endothelium and on numerous infiltrating cells in the fibrous tissue areas in cases of nodular sclerosing disease. Reed-Sternberg and Hodgkin's cells were not labelled by either anti-fibronectin or by antibodies reactive with dendritic reticulum cells (anti-C3b receptor and antibody R4/23).

The ultrastructural heterogeneity of the Reed-Sternberg cell and its resemblance to monocyte-macrophage differentiation in vivo

Hodgkin's disease is a malignant neoplasm that shares many histologic features with granulomatous diseases. We have examined 11 cases of Hodgkin's disease, representing the spectrum of histologic types, using transmission electron microscopy and have compared the morphology of Reed-Sternberg cells to that of the developmental stages described for monocyte-macrophage differentiation in vivo. Ultrastructurally, a close parallelism exists between the cells that typify granulomatous inflammation and Reed-Sternberg cells. It is our contention that the heterogeniety among Reed-Sternberg cells in all types of Hodgkin's disease parallels the diversity of the monocyte-macrophage system.

Studies of lectin binding to normal and neoplastic lymphoid tissues. I. Normal nodes and Hodgkin's disease

Lectins are proteins which have the ability to interact specifically with carbohydrate residues of glycoproteins and other glycoconjugates. The staining patterns of 10 fluorescein conjugated lectins (F-Con A, F-LCA, F-RCA, F-WGA, F-PHA, F-PWM, F-LTA, F-SBA, F-PNA, F-DB) and a protease inhibitor (F-LA) have been studied in histological sections of 11 normal or reactive lymph nodes and 6 nodes and one skin biopsy involved by Hodgkin's disease. On the basis of the patterns of lectin binding, and current knowledge of their saccharide specificities, we found that within germinal centres there is an orderly carbohydrate rich extracellular matrix which contains a higher concentration of GlcNAc and terminal Gal residues than the surface membranes of component cells. This suggests active secretion rather than simple membrane shedding, and it is possible that this pericellular domain plays a part in the regulation of the proliferative response, or controls migration of lymphocytes in and out of the germinal centre. Lectin binding in Reed-Sternberg cells suggests that the huge nucleoli contain glycoconjugates of diverse structure, which may be linked with their failure to undergo cytokinesis.

Hodgkin and Sternberg-Reed cells contain antigens specific to late cells of granulopoiesis

The results of a recent investigation, in which an antiserum specifically directed against Hodgkin (H) and Sternberg-Reed (SR) cells was prepared, indicated the existence of a granulocytic cell-specific antigen on H and SR cells. In the present study, a large series of biopsies from patients with Hodgkin's disease were subjected to immunostaining with monoclonal mouse antibodies raised against acute myelomonocytic leukemia (AMML) cells. Among seven hybrids that secreted antibodies showing reactivity to AMML cells but not to Daudi cells, there were three (TU5, TU6 and TU9) whose antibodies selectively stained formalin resistant antigens in cells of granulopoiesis. The strongest staining was found in the more mature cells; only a few promyelocytes stained very faintly with TU9, H and SR cells showed distinct staining for TU9 in 57 (76%) of the 75 tested cases of Hodgkin's disease, whereas TU5 and TU6-reactive H and SR cells were found in only 35 cases (47%). All cases of the nodular sclerosis type and almost all cases of the mixed cellularity type contained TU9-reactive H and SR cells, although the percentage varied from case to case. TU9-reactive H and SR cells were demonstrated in nine of 12 cases of the lymphocyte depletion type and in eight of 21 cases of the lymphocyte predominance type. The presence of granulocytic cell-specific antigens in H and SR cells in most of the cases of Hodgkin's disease suggest that (1) H and SR cells (including the lacunar cell variant) are not heterogeneous, but rather homogeneous in origin and nature, at least in a majority of cases, and (2) H and SR cells are more closely related to cells of the granulocytic cell lineage than to any other type of cell of the hemato-lymphoid system.

Macrophage origin of Reed-Sternberg cells: an immunohistochemical study

In an immunohistochemical study of 26 biopsies from 24 patients with Hodgkin's disease a granular staining pattern for alpha-1-antitrypsin (alpha(1)AT) and alpha-1-antichymotrypsin (alpha(1)ACT) was seen in Reed-Sternberg (RS) cells and mononuclear Hodgkin's (H) cells in over half the cases. The pattern of staining for these antiproteases seen in RS and H cells has previously only been observed in normal and malignant cells of the monocyte/macrophage lineage within the lymphoreticular system. A faintly granular evenly distributed staining for IgG was found in viable RS and H cells. This staining was associated with a similar distribution of both light chains but not J chain, suggesting that the immunoglobulin had not been synthesised by these cells but had been taken up from the extracellular environment. It is suggested that this uptake is an active process occurring in viable RS and H cells, possibly via Fcgamma receptors and further supports an origin from cells of the monocyte/macrophage lineage. IgA, IgD, albumin, fibrinogen, C1q, C4 and C3 were present in some cells, IgM was more rarely found and lysozyme was absent. The fact that cells staining for these serum proteins generally showed signs of degeneration and that the extent of staining correlated with the molecular weight, but not serum concentration, of the protein suggests that they are passively acquired by dead or dying cells and thus represent a separate phenomenon from IgG uptake. The function of IgG uptake and accumulation by RS cells and the alpha(1)AT and alpha(1)ACT markers may prove of use in identifying the macrophage subtype from which these cells are derived.

Two neoplastic cell lines with unique features derived from Hodgkin's disease

Two in vitro cell lines (L428, L439) were established from pleural effusions of two patients with Hodgkin's disease. The histological diagnosis was ascertained in both cases by two independent pathologists. The neoplastic nature of the culture cells is indicated by the demonstration of several structural and numerical chromosome abnormalities associated with a monoclonal pattern of marker chromosomes. Heterotransplantation in nude mice was achieved by intracranial inoculation and by subcutaneous transplantation of cultured cells embedded in a plasma clot. EBV-specific antigens (EBNA, VCA) were not detectable in either cell line. Ia-like antigens, receptors for T cells, acid phosphatase and acid esterase were shown to be present in the cultured cells. The L428 and L439 cell line lacked surface- or cytoplasmic Ig, HTLA, receptors for C3b, C3d, IgG-Fc, mouse E or sheep E, and were devoid of lysozyme, peroxidase and chloracetate esterase. These features do not correspond to those of B cells, T cells, myeloid cells, monocytes or macrophages; the morphology and the marker pattern of the culture cells, however, is identical with that of freshly obtained Hodgkin (H)- and Sternberg-Reed (SR)- cells, except for the lack of Clg in the in vitro cells, which is explained by the culture conditions. These findings suggest that the L428 and L439 cell lines are indeed derived from H- and SR-cells and offer the possibility of gaining new information upon the nature of Hodgkin's disease.

The localization of Hodgkin's disease in lymph nodes. A study with immunohistological, enzyme histochemical and rosetting techniques on frozen sections

Lymphoid tissue of 51 patients with Hodgkin's disease was studied with immunohistological, enzyme histochemical and rosetting techniques for the detection of B and T cells in frozen sections. In lymph nodes of patients with lymphocyte predominance type of Hodgkin's disease, the majority of the lymphocytes in the involved areas were normal B lymphocytes of polyclonal origin. This was also true for nodular sclerosis cases with a predominance of lymphocytes. Surrounding Sternberg-Reed cells small clusters of T lymphocytes could be demonstrated. In mixed cellularity and also in nodular sclerosis with a mixed cellular pattern only small residual areas of B lymphocytes were present, whereas relatively large numbers of T lymphocytes were found in the involved areas. In lymphocyte depletion B lymphocytes were scarce and T lymphocytes were present in small number. It is concluded that different patterns of lymphocyte population can be discerned in the subtypes of Hodgkin's disease. A predominance of B lymphocytes is found in cases with lymphocyte predominance and thus is a prognostic favourable sign. A predominance of T lymphocytes as found in cases with a mixed cellular pattern with or without nodular sclerosis is therefore not a favourable sign in general but may indicate progressive disease. The possible reasons for the presence of large numbers of B or T lymphocytes in lymphoid tissue affected by Hodgkin's disease are discussed.

The immunopathology of Hodgkin's disease

Answers are beginning to emerge to the questions posed in the introduction to the preceding section. In vitro techniques that allow characterization of malignant cells have particular relevance when, as in Hodgkin's disease, the precise identity of the cells remains in doubt. Monolayer tissue cultures derived from Hodgkin's disease tumours and maintained as established cell lines have proven amenable to a variety of cytogenetic, immunological, enzymatic, and ultrastructural studies. Tissue culture experiemnts, in conjunction with meticulous immunological studies of individual Reed-Sternberg cells from non-cultured tumours, suggest that neoplastic cells of Hodgkin's disease are related to, and possibly derived from, cells of the monocyte-macrophage system. The lymphocytes that comprise an integral part of the cellular proliferation and form the basis for histological subclassification of the tumour could be a manifestation of cell-mediated immunity against this non-lymphoid malignant cell. The immunodeficiency of patients with untreated Hodgkin's disease of limited anatomical extent is not the primary event of the disorder and probably not related to the site at which the aetiological agent acts. The deficit does not result solely from impaired T-cell function and appears to arise as a consequence of excessive suppressor cell activity. Inhibitory monocyte-lymphocyte interactions may be one of the causes of defective cell-mediated immunity in Hodgkin's disease. The possible significance of elevated levels of circulating immune complexes in the serum of patients with Hodgkin's disease is indicated by the finding that such complexes react with cells of long-term monolayer tissue cultures derived from the tumour. Circulating immune complexes may be one source for intracellular immunoglobulin in non-cultured Hodgkin's disease cells. The presence of polyclonal immunoglobulin G on the membrane and within the cytoplasm of Reed-Sternberg cells could be due to in vivo binding and ingestion of immune complexes by such cells. The specificity of the interaction between soluble complement-containing immune complexes and neoplastic cells of Hodgkin's disease depends on the nature of the complexed antigen. The complexes could non-specifically attach via an Fc receptor or, if the complexed antigen is identical to a tumour cell antigen, the binding could be specific. If the immune complexes are tumour specific they could provide a source for isolation and identification of tumour-associated antigens. However, the aetiological significance of antigens and putative oncogenic viruses thus far identified in association with Hodgkin's disease remains to be clarified.

Acid alpha-naphthyl acetate esterase (ANAE) activity and DNA synthesis of lymph nodes cells in Hodgkin's disease

Lymph node and peripheral blood lymphocytes in a case of Hodgkin's disease (mixed cellularity) were studied using May-Grünwald-Giemsa (MGG), acid naphthyl acetate esterase (ANAE), immunoperoxidase staining and lymphocyte surface markers, autoradiographic, and lymphocyte stimulation techniques. According to MGG staining and autoradiographic studies of lymph, node cells, small lymphocytes, intermediate lymphoid cells, and large mononuclear cells resembling in-vitro stimulated immunoblasts, Hodgkin's cells and Reed-Sternberg (RS) cells formed a morphologically continuous DNA synthetizing series. A large majority of small lymphocytes from a lymph node were ANAE positive, thus being T-lymphocytes, and formed rosetts around large mononuclear cells and RS cells. Most RS and large mononuclear cells had ANAE positive spots in the cytoplasm, thus resembling T-lymphocytes more than diffusely staining monocytes. These cells did not contain cytoplasmic immunoglobulin and were muramidase negative. Both lymph node and peripheral blood lymphocytes responded strongly to PHA. The role of T-lymphocytes in Hodgkin's disease and the origin of RS cells are are discussed on the basis of the findings.

Electron microscopy of Hodgkin's disease tissue cultures

Cells from 9 monolayer tissue cultures prepared from Hodgkin's disease tumors in the spleen were examined in the electron microscope. Three established culture lines (carried in vitro for greater than 3 years and passaged greater than 200 times) that contained aneuploid karyotypes were composed of oval cells with numerous interdigitating surface microvilli. The nuclei were complex and convoluted with multiple large nucleoli and dispersed chromatin. The cytoplasm contained lysosomes, microfilaments, a complex Golgi apparatus, nondilated rough endoplasmic reticulum, polyribosomes, fat, and glycogen. One Hodgkin's disease monolayer with aneuploid chromosomes examined from the 4th to 48th passage in culture was composed of larger cells with fewer microvilli and numerous multinuclear giant cells. Two monolayers derived from transplanted tumors in nude mice inoculated with Hodgkin's disease cultured cells were similar to the original cell lines. The ultrastructural features of these 6 cultures with aneuploid karyotypes differed from those of 3 monolayers which, although prepared from Hodgkin's disease splenic tumors, were composed of fibroblastic cells with diploid chromosomes. The aneuploid Hodgkin's disease cultures did not resemble 6 normal spleen, thymus, or lung monolayers, Raji lymphoblastoid suspension cultures, or Hela cells. Our electron microscopic studies indicate that adherent cells which replicate in some monolayer tissue cultures derived from Hodgkin's disease tumors are related to and possibly derived from neoplastic macrophages.

Analysis of physical parameters of discrete cell populations. (Double data control by combining specific density and sedimentation velocity cell separation techniques)

Physical cell separations are employed in a number of investigations in cell biology, immunology, haematology, etc., when the study of homogeneous cell populations is required. Differences in physical characters are reflected in the various functions and differentiation stages of the individual cell lines, which can be concentrated and separated into discrete cell classes by these methods. The correct utilization of the separation techniques mainly depends on the knowledge of the physical laws on which they are based. This paper discusses the theoretical background and a practical application of a combined separation procedure which uses velocity sedimentation and linear density gradient and also gives a double check of the physical data obtained in the different experiments. As an example of this analysis, cells from the lymph nodes of Hodgkin's patients were separated, and the physical parameters as well as some sources of 'error' in the experimental results obtained with these 'Hodgkin's cells' are reported and discussed.

Properties of anti-hairy cell serum

An antiserum was prepared in rabbits against hairy leukaemic cells. After absorption with human erythrocytes, thymus and liver powder, the serum was passed through immunoabsorbent columns to remove extensive anti-plasma protein activity. Following these procedures, sensitive techniques failed to reveal residual activity against alpha-macroglobulins, beta2-microglobulin and other human plasma proteins. The antiserum reacted with normal B lymphocytes but not with T lymphocytes or monocytes. Positive reactions were seen in B cell lymphomas, chronic lymphocytic leukaemia, hairy-cell leukaemia and uninucleated Reed-Sternberg cells.