Circulating CD4+ T lymphocytes with intracellular but no surface CD3 antigen in five of seven patients consecutively diagnosed with angioimmunoblastic T-cell lymphoma

Reactive Eosinophil Proliferations in Tissue and the Lymphocytic Variant of Hypereosinophilic Syndrome

OBJECTIVES

The 2019 Society for Hematopathology and European Association for Haematopathology Workshop reviewed the spectrum of neoplastic, nonneoplastic, and borderline entities associated with reactive eosinophilia in tissue.

METHODS

The workshop panel reviewed 46 cases covered in 2 workshop sessions.

RESULTS

The 46 cases were presented with their consensus diagnoses during the workshop. Reactive eosinophilia in lymph nodes and other tissues may be accompanied by or be distinct from peripheral blood eosinophilia. Reactive etiologies included inflammatory disorders such as Kimura disease and IgG4-related disease, which may show overlapping pathologic features and reactions to infectious agents and hypersensitivity (covered in a separate review). Hodgkin, T-cell, and B-cell lymphomas and histiocytic neoplasms can result in reactive eosinophilia. The spectrum of these diseases is discussed and illustrated through representative cases.

CONCLUSIONS

Reactive eosinophilia in lymph nodes and tissues may be related to both nonneoplastic and neoplastic lymphoid proliferations and histiocytic and nonhematolymphoid processes. Understanding the differential diagnosis of reactive eosinophilia and the potential for overlapping clinical and pathologic findings is critical in reaching the correct diagnosis so that patients can be treated appropriately.

Evaluation of a 10color protocol as part of a 2tube screening panel for flow cytometric assessment of peripheral blood leukocytic subsets

Peripheral blood (PB) immunophenotyping is commonly required for initial evaluation of various suspected disease entities. Several approaches have been proposed. The objective of this work is to explore the value of a 10color protocol developed in our laboratory for flow cytometric assessment of PB leukocytic subsets, as part of a 2tube screening panel. A combination of CD16/CD56/CD34/CD33/CD19/CD4/CD8/CD3/CD20/CD45 antibodies in 1 tube was applied routinely during flow cytometric analysis of PB samples for diagnostic purposes. The protocol was systematically complemented by a 2nd tube with anti-kappa, anti-lambda, CD5, CD19, and CD45 antibodies for adults and selected pediatric patients, and specifically oriented panels when necessary. 25 samples with no detectable neoplastic PB involvement and 31 samples with a hematolymphoid disorder were investigated retrospectively. The contribution of CD33 in the separation of leukocytic populations, as well as the benefits from the simultaneous assessment of CD20/CD19/CD45, CD16/CD56 and the detection of CD34+ cells were examined. The gating strategy with the use of CD33 provided additional information in certain cases. The protocol enabled recognition of differential expression of CD20 and CD45 in CD19+ cells with chronic lymphocytic leukemia phenotype, overall evaluation of NK and NK like T cells, estimation of CD16- granulocytes and CD56/CD16 expression in monocytes, as well as identification of minor cell subsets, such as CD34+ cells. The proposed 10color combination of antibodies analyzed in a standardized manner can offer significant information in the initial evaluation of PB samples, thus, guiding subsequent investigation if needed.

Angioimmunoblastic T-Cell Lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is one of the most common types of T-cell lymphoma, representing about 15-20% of cases of peripheral T-cell lymphoma (PTCL). It is characterized by a unique clinical presentation and distinct pathologic and molecular features. Classes of drugs particularly active in AITL are emerging; however, treatment of relapsed and refractory disease remains a challenge. This chapter reviews the epidemiology, clinical presentation, pathogenesis, diagnosis, and treatment of AITL.

Specific immunotypes of canine T cell lymphoma are associated with different outcomes

Canine lymphoma is a heterogeneous disease with many different subtypes. Lymphoma of T cell type in particular is variable in outcome, and includes subtypes with non-progressive, slowly- and rapidly-progressive disease course. Association of immunotype with disease course is incompletely defined. Here, results of flow cytometric immunotyping of 127 canine T cell lymphomas were analyzed in relation to survival and progression free interval. Samples originated from 101 multicentric, 8 mediastinal, 6 cutaneous, 5 hepatosplenic, 5 gastrointestinal and 2 other anatomic subtypes of T cell lymphoma. Compared to multicentric T cell lymphoma, gastrointestinal lymphoma had shorter survival and progression free interval, and hepatosplenic lymphoma had shorter survival. Among dogs with multicentric T cell lymphoma, immunotypes of CD4⁺/CD8^-/MHCII⁺, CD4^-/CD8⁺/MHCII⁺ and CD4^-/CD8⁺/MHCII^- were associated with longer survival times than the immunotype of CD4⁺/CD8^-/MHCII^-, and immunotypes of CD4⁺/CD8^-/MHCII⁺, CD4^-/CD8⁺/MHCII^-, and CD4^-/CD8^-/MHCII⁺ were associated with longer progression free intervals. Dogs with multicentric T cell lymphoma and concurrent leukemia had shorter survival but similar progression free interval compared to those without leukemia. Body weight, sex, hypercalcemia, cell size, expression of CD3 and use of combination or single agent chemotherapy did not significantly affect outcome of multicentric TCL.

Peripheral T-cell lymphomas of follicular helper T-cell type frequently display an aberrant CD3(-/dim)CD4(+) population by flow cytometry: an important clue to the diagnosis of a Hodgkin lymphoma mimic

Nodal follicular helper T-cell-derived lymphoproliferations (specifically the less common peripheral T-cell lymphomas of follicular type) exhibit a spectrum of histologic features that may mimic reactive hyperplasia or Hodgkin lymphoma. Even though angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma of follicular type share a common biologic origin from follicular helper T-cells and their morphology has been well characterized, flow cytometry of peripheral T-cell lymphomas of follicular type has not been widely discussed as a tool for identifying this reactive hyperplasia/Hodgkin lymphoma mimic. We identified 10 peripheral T-cell lymphomas of follicular type with available flow cytometry data from five different institutions, including two cases with peripheral blood evaluation. For comparison, we examined flow cytometry data for 8 classical Hodgkin lymphomas (including 1 lymphocyte-rich classical Hodgkin lymphoma), 15 nodular lymphocyte predominant Hodgkin lymphomas, 15 angioimmunoblastic T-cell lymphomas, and 26 reactive nodes. Lymph node histology and flow cytometry data were reviewed, specifically for the presence of a CD3(-/dim)CD4(+) aberrant T-cell population (described in angioimmunoblastic T-cell lymphomas), besides other T-cell aberrancies. Nine of 10 (90%) peripheral T-cell lymphomas of follicular type showed a CD3(-/dim)CD4(+) T-cell population constituting 29.3% (range 7.9-62%) of all lymphocytes. Five of 10 (50%) had nodular lymphocyte predominant Hodgkin lymphoma or lymphocyte-rich classical Hodgkin lymphoma-like morphology with scattered Hodgkin-like cells that expressed CD20, CD30, CD15, and MUM1. Three cases had a nodular growth pattern and three others exhibited a perifollicular growth pattern without Hodgkin-like cells. Epstein-Barr virus was positive in 1 of 10 cases (10%). PCR analysis showed clonal T-cell receptor gamma gene rearrangement in all 10 peripheral T-cell lymphomas of follicular type. By flow cytometry, 11 of 15 (73.3%) angioimmunoblastic T-cell lymphomas showed the CD3(-/dim)CD4(+) population (mean: 19.5%, range: 3-71.8%). Using a threshold of 3% for CD3(-/dim)CD4(+) T cells, all 15 nodular lymphocyte predominant Hodgkin lymphoma controls and 8 classical Hodgkin lymphomas were negative (Mann-Whitney P=0.01, F-PTCL vs Hodgkin lymphomas), as were 25 of 26 reactive lymph nodes. The high frequency of CD3(-/dim)CD4(+) aberrant T cells is similar in angioimmunoblastic T-cell lymphomas and peripheral T-cell lymphomas of follicular type, and is a useful feature in distinguishing peripheral T-cell lymphomas of follicular type from morphologic mimics such as reactive hyperplasia or Hodgkin lymphoma.

Immunophenotypic and diagnostic characterization of angioimmunoblastic T-cell lymphoma by advanced flow cytometric technology

Angioimmunoblastic T-cell lymphoma (AITL) often shows systemic symptoms related to immune dysregulation and cytokine production. Biopsy usually harbors few malignant cells in an abundant reactive background, which can be diagnostically challenging in cases with small biopsies. This study was performed to assess the value of flow cytometry (FC) and to determine the immunophenotypic alterations in 155 samples from 38 patients with AITL. FC detected an aberrant T-cell population in 97 of 155 samples that represented 0.5-90% of lymphocytes. Blood was involved in 11 of 16 patients. The most frequent immunophenotypic aberrancies included loss of CD3; altered T-cell receptor expression and aberrant CD10 expression. Altered CD3 expression was more frequently seen in peripheral blood (PB) and bone marrow (BM), whereas aberrant CD10 expression was more common in lymph node (LN). AITL cells often exhibit abnormal CD4⁺ immunophenotype with diminished or absent CD3 and variable CD10 expression. Multiparameter FC is an effective tool for supporting the diagnosis of AITL in any fluid and various tissue specimens types.

CD3-CD4+ lymphoid variant of hypereosinophilic syndrome: nodal and extranodal histopathological and immunophenotypic features of a peripheral indolent clonal T-cell lymphoproliferative disorder

The CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome is characterized by hypereosinophilia and clonal circulating CD3(-)CD4(+) T cells. Peripheral T-cell lymphoma has been described during this disease course, and we observed in our cohort of 23 patients 2 cases of angio-immunoblastic T-cell lymphoma. We focus here on histopathological (n=12 patients) and immunophenotypic (n=15) characteristics of CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome. Atypical CD4(+) T cells lymphoid infiltrates were found in 10 of 12 CD3(-)CD4(+) L-HES patients, in lymph nodes (n=4 of 4 patients), in skin (n=9 of 9) and other extra-nodal tissues (gut, lacrymal gland, synovium). Lymph nodes displayed infiltrates limited to the interfollicular areas or even an effacement of nodal architecture, associated with proliferation of arborizing high endothelial venules and increased follicular dendritic cell meshwork. Analysis of 2 fresh skin samples confirmed the presence of CD3(-)CD4(+) T cells. Clonal T cells were detected in at least one tissue in 8 patients, including lymph nodes (n=4 of 4): the same clonal T cells were detected in blood and in at least one biopsy, with a maximum delay of 23 years between samples. In the majority of cases, circulating CD3(-)CD4(+) T cells were CD2(hi) (n=9 of 14), CD5(hi) (n=12 of 14), and CD7(-)(n=4 of 14) or CD7(low) (n=10 of 14). Angio-immunoblastic T-cell lymphoma can also present with CD3(-)CD4(+) T cells; despite other common histopathological and immunophenotypic features, CD10 expression and follicular helper T-cell markers were not detected in lymphoid variant of hypereosinophilic syndrome patients, except in both patients who developed angio-immunoblastic T-cell lymphoma, and only at T-cell lymphoma diagnosis. Taken together, persistence of tissular clonal T cells and histopathological features define CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome as a peripheral indolent clonal T-cell lymphoproliferative disorder, which should not be confused with angio-immunoblastic T-cell lymphoma.

Abnormal immunophenotype of the T-cell-receptor beta Chain in follicular-helper T cells of angioimmunoblastic T-cell lymphoma

OBJECTIVE

Analysis for 24 variable regions of the T-cell-receptor beta chain by flow cytometry (Vbeta) is a new technique to detect clonal alpha-beta T lymphocytes and is characteristically performed on peripheral blood. Angioimmunoblastic T-cell lymphoma (AITL) has increased neoplastic follicular-helper T cells (FHT), which often express CD10; but nonneoplastic, CD10-positive T cells may be associated with reactive lymphadenopathy and with B-cell lymphomas. This study documents the utility of Vbeta analysis of FHT in specimens of AITL from blood, from marrow, and from lymph nodes.

METHODS

The electronic medical record in the flow cytometry laboratory was searched for specimens that were analyzed by flow cytometry for Vbeta and that were involved by AITL. Flow cytometry was performed for the following antigens: T-cell-associated proteins, CD10, CD56, CD94, CD161, killer-cell immunoglobulin-like receptors, alpha-beta T-cell receptor, gamma-delta T-cell receptor, and Vbeta.

RESULTS

Five patients had six specimens of blood (two), of bone marrow (one), or of lymph nodes (three). Immunophenotypic aberrances were detected for antigens: CD2 (2/6), CD3 (6/6), CD4 (1/6), CD5 (1/6), CD7 (5/6), and CD45 (2/6). All abnormal T-cell populations expressed CD4, and most expressed CD10 (5/6). Four specimens were clonally restricted for Vbeta. Two specimens lacked the alpha-beta T-cell receptor and Vbeta.

CONCLUSIONS

Vbeta analysis by flow cytometry can be used to detect clonal alpha-beta FHT in AITL, which may be difficult to diagnose with early involvement. Abnormal Vbeta expression on CD10-positive T cells confirms that FHT are the neoplastic cells.

Peripheral blood sCD3⁻ CD4⁺ T cells: a useful diagnostic tool in angioimmunoblastic T cell lymphoma

Angioimmunoblastic T cell lymphoma (AITL) belongs to the subgroup of mature T cell lymphomas according to the World Health Organization and is one of the common T cell lymphomas in Western countries. Particularly in cases in which histological confirmation cannot be easily achieved, immunophenotyping of peripheral blood can give important information for the differential diagnosis of AITL. sCD3⁻ CD4⁺ T cells are a typical feature of AILT in flow cytometry of peripheral blood. In this retrospective study, the diagnostic value of flow cytometry for the diagnosis 'AITL' was assessed by comparing the frequency of sCD3⁻ CD4⁺ T cells in leukemic AITL patients and in patients with other leukemic CD4⁺ T cell lymphomas. Immunophenotyping of peripheral blood by flow cytometry was performed in a lymphocyte gate using fluorochrome-labelled antibodies against CD3, CD2, CD4, CD5, CD7, CD8, CD10, CD14, CD16, CD19, CD56, CD57 and T cell receptor. In 17/17 leukemic AITL patients, a small but distinct population of sCD3⁻ CD4⁺ T cells was detected (mean percentage of sCD3⁻ CD4⁺ T cells in the lymphocyte gate: 11.9 ± 15.4%, range 0.1-51.8%). In contrast, sCD3⁻ CD4⁺ T cells were found in only 1/40 patients with other leukemic CD4⁺ T cell lymphomas (one patient with mycosis fungoides). sCD3⁻ CD4⁺ T cells have a high positive predictive value (94%) for the diagnosis 'AITL'. Flow cytometry is particularly useful in the differential diagnosis of AITL, even if the aberrant T cell population has a very low frequency. Further biological characterization of this subfraction of lymphoma cells is warranted.

Targeting intratumoral B cells with rituximab in addition to CHOP in angioimmunoblastic T-cell lymphoma. A clinicobiological study of the GELA

BACKGROUND

In angioimmunoblastic T-cell lymphoma, symptoms linked to B-lymphocyte activation are common, and variable numbers of CD20(+) large B-blasts, often infected by Epstein-Barr virus, are found in tumor tissues. We postulated that the disruption of putative B-T interactions and/or depletion of the Epstein-Barr virus reservoir by an anti-CD20 monoclonal antibody (rituximab) could improve the clinical outcome produced by conventional chemotherapy.

DESIGN AND METHODS

Twenty-five newly diagnosed patients were treated, in a phase II study, with eight cycles of rituximab + chemotherapy (R-CHOP21). Tumor infiltration, B-blasts and Epstein-Barr virus status in tumor tissue and peripheral blood were fully characterized at diagnosis and were correlated with clinical outcome.

RESULTS

A complete response rate of 44% (95% CI, 24% to 65%) was observed. With a median follow-up of 24 months, the 2-year progression-free survival rate was 42% (95% CI, 22% to 61%) and overall survival rate was 62% (95% CI, 40% to 78%). The presence of Epstein-Barr virus DNA in peripheral blood mononuclear cells (14/21 patients) correlated with Epstein-Barr virus score in lymph nodes (P<0.004) and the detection of circulating tumor cells (P=0.0019). Despite peripheral Epstein-Barr virus clearance after treatment, the viral load at diagnosis (>100 copy/μg DNA) was associated with shorter progression-free survival (P=0.06).

CONCLUSIONS

We report here the results of the first clinical trial targeting both the neoplastic T cells and the microenvironment-associated CD20(+) B lymphocytes in angioimmunoblastic T-cell lymphoma, showing no clear benefit of adding rituximab to conventional chemotherapy. A strong relationship, not previously described, between circulating Epstein-Barr virus and circulating tumor cells is highlighted.

CD10 and ICOS expression by multiparametric flow cytometry in angioimmunoblastic T-cell lymphoma

Angioimmunoblastic T-cell lymphoma is immunologically defined by the expression of CD10 and the follicular helper T cell (T(FH)) markers such as CXCL13, programmed death-1 (PD-1) and inducible T-cell costimulator (ICOS). This T(FH) profile has been mainly reported by immunohistochemistry. Here, using multiparametric flow cytometry, the relevance of ICOS and PD-1 to angioimmunoblastic T-cell lymphoma diagnosis was evaluated in lymph node (n=15) as well as in peripheral blood (n=13) among a series of 28 angioimmunoblastic T-cell lymphoma cases, in addition to the CD10 expression (available in 26 lymph node and 15 peripheral blood specimens). In this series, CD10 expression was present in 23/26 (88%) lymph node and in 12/15 (80%) peripheral blood cases and ICOS in 13/15 (87%) lymph node and in 6/13 (47%) peripheral blood cases, whereas neither significant CD10 nor ICOS T cells were identified in the control group (lymph nodes with reactive hyperplasia=10, peripheral blood of healthy donors=15). PD-1 expression was less informative as observed in both angioimmunoblastic T-cell lymphoma and control cases. The multiparametric approach allowed us to confirm the frequent blood dissemination in angioimmunoblastic T-cell lymphoma and to show that circulating neoplastic T cells correspond more often to a CD10-positive subset than to an ICOS-positive subset. Consequently, if ICOS constitutes an additional feature for the diagnosis of angioimmunoblastic T-cell lymphoma, it appears less sensitive than CD10 expression for the detection of circulating neoplastic T cells.

The inducible T-cell co-stimulator molecule is expressed on subsets of T cells and is a new marker of lymphomas of T follicular helper cell-derivation

BACKGROUND

T follicular helper (T(FH)) cells reside in the light zone of germinal centers and are considered the cell of origin of angioimmunoblastic T-cell lymphoma. Recently, CXCL13, PD-1 and SAP were described as useful markers for T(FH) cells and angioimmunoblastic T-cell lymphoma but also reported in some peripheral T-cell lymphomas, not otherwise specified.

DESIGN AND METHODS

In the present study the expression pattern of ICOS protein was investigated by immunohistochemistry-based techniques in routine sections of normal lymphoid tissues and 633 human lymphomas.

RESULTS

Cells strongly positive for ICOS were restricted to the light zone of germinal centers and co-expressed T(FH)-associated molecules. In addition, weak to moderate ICOS expression was observed in a small proportion of FOXP3-positive cells. In lymphomas, ICOS expression was confined to angioimmunoblastic T-cell lymphoma (85/86), peripheral T-cell lymphomas of follicular variant (18/18) and a proportion of peripheral T-cell lymphomas, not otherwise specified (24/56) that also expressed other T(FH)-associated molecules.

CONCLUSIONS

ICOS is a useful molecule for identifying T(FH) cells and its restricted expression to angioimmunoblastic T-cell lymphoma and a proportion of peripheral T-cell lymphomas, not otherwise specified (showing a T(FH)-like profile) suggests its inclusion in the antibody panel for diagnosing T(FH)-derived lymphomas. Our findings provide further evidence that the histological spectrum of T(FH)-derived lymphomas is broader than previously assumed.

Lymphocytic Variant Hypereosinophilic Syndromes

A large body of evidence establishing the existence of an underlying T-cell disorder in a subset of patients fulfilling hypereosinophilic syndrome (HES) diagnostic criteria has accumulated over the past decade, resulting in the definition of a novel HES variant termed "lymphocytic" HES. Although end-organ complications of hypereosinophilia are generally benign, with predominant cutaneous manifestations, long-term prognosis is overshadowed by an increased risk of developing T-cell lymphoma, as a result of malignant transformation of aberrant T cells years after HES diagnosis. Therapeutic strategies should target pathogenic T cells in addition to eosinophils, but the practical implications remain largely unexplored.

Characterization of CXCL13+ Neoplastic T Cells in Cutaneous Lesions of Angioimmunoblastic T-cell Lymphoma (AITL)

Skin manifestations of angioimmunoblastic T-cell lymphoma (AITL) are frequent, sometimes as first manifestations of the disease. In the absence of a specific marker for neoplastic cells, diagnosis of AITL in skin biopsies is often difficult. CD10 and CXCL13 have been recently recognized as characteristic markers of AITL, but have not been yet investigated in the skin. We analyzed 15 skin biopsies from 8 patients with AITL having skin manifestations and compared them to 14 skin biopsies from patients with various cutaneous lymphocytic infiltrates. A few CD10 lymphocytes were found in only 2 samples of the AITL group, the identification of which was hampered by the presence of a dermal CD10 cell population with dendritic features. By contrast, CXCL13 lymphoid cells were identified in most AITL cutaneous biopsies (n=12, 80%), whereas, absent in all samples from control cases. Among 12 biopsies with CXCL13 cells, cutaneous involvement by AITL was suspected in only 5 on the basis of light microscopy and classic immunophenotyping. In another case, a diagnosis of cutaneous marginal zone B-cell lymphoma had been proposed. In conclusion, this study shows that neoplastic AITL CXCL13 T cells localize in the skin and that accurate diagnosis of AITL lesions can be done in skin specimens using CXCL13 immunostaining on paraffin-embedded tissues.

Flow cytometric features of angioimmunoblastic T-cell lymphoma

BACKGROUND

The immunophenotypic features of angioimmunoblastic T-cell lymphoma (AILT) have not been well described.

METHODS

We retrospectively reviewed our institutional experience with the flow cytometric features of 16 cases of AILT.

RESULTS

Multiparameter flow cytometry was able to identify a distinct population of immunophenotypically aberrant T cells in 15 of 16 cases. In 13 lymph node specimens, the neoplastic cells ranged from 1.9 to 87% (median 23%) of cells. The ratio of reactive to neoplastic T cells ranged from 0.01 to 20 (median 1.5); reactive T cells outnumbered neoplastic in 9/13 (69%) cases. The neoplastic populations expressed CD2, CD4, CD5, and CD45RO in all cases, lacked expression of CD8 and CD56 in all cases, and showed negative or dim surface CD3 in most cases. CD10 was expressed by the neoplastic populations in 11 of 14 cases at diagnosis; in 3 of these 11 only a subpopulation of the neoplastic cells was CD10(+). CD10 tended to be absent on neoplastic cells in staging bone marrows. The neoplastic population in all but one of the 15 positive cases possessed multiple immunophenotypic abnormalities and these were generally retained during the follow-up analyses of several cases.

CONCLUSIONS

These results indicate the potential utility of flow cytometry in the diagnosis and follow-up of AILT.

Identification of circulating CD10 positive T cells in angioimmunoblastic T-cell lymphoma

In most cases of lymphomas with blood dissemination, the careful cytological analysis of peripheral blood smears provides a rapid orientation to diagnosis, even if the final subtyping is achieved by histology and eventually other techniques. Here, we evaluated if the analysis of blood smears may suggest the blood dissemination of angioimmunoblastic T-cell lymphoma (AITL) and if CD10 expression on neoplastic T cells, as recently reported on AITL, may contribute to the diagnosis. In all, 11 lymph nodes and six peripheral blood samples from 12 patients with AITL were studied using four-colour flow cytometry associated to histological, cytological and molecular data. According to previous results, a fraction of T cells expressed CD10 in 10/11 lymph nodes. Interestingly, all blood smears showed atypical lymphoid cells and a fraction of T cells expressed CD10 with a mean percentage of 18.75% (range 5.00-47.00%), regardless of lymphocytosis level and of rate of CD10 T cells in corresponding lymph node. In contrast, in all control samples (100), none CD10-positive T cell was identified. This is to our knowledge the first description of circulating CD10 neoplastic T cells in AITL. Therefore, they ought to be explored in further studies when aggressive lymphoma, in particular with lymphopenia and circulating atypical cells, is suspected.

Defective CD3γ gene transcription is associated with NFATc2 overexpression in the lymphocytic variant of hypereosinophilic syndrome

OBJECTIVE

Determine the molecular defects underlying the CD3(-)CD4(+) T-cell phenotype and persistence of this clonal population in patients with hypereosinophilic syndrome.

PATIENTS AND METHODS

Patients in this study suffer from the lymphocytic variant of hypereosinophilic syndrome distinguished by a CD3(-)CD4(+) T-cell clone that overexpresses Th2 cytokines upon activation and thereby provokes the eosinophilia. Interleukin-2-dependent CD3(-)CD4(+) T-cell lines were derived from patient blood at various disease stages and used to investigate the molecular modifications correlated with their abnormal phenotype.

RESULTS

We demonstrate that the CD3(-)CD4(+) T cells, characterized by a clonal TCRbeta gene rearrangement, maintained the same immunophenotype over the 6-year period of our study, during which one patient progressed from premalignant disease to CD3(-)CD4(+) T-cell lymphoma. We show that a specific loss of CD3gamma gene transcripts is responsible for the defect in TCR/CD3 surface expression. In addition, the level of NFATc2 binding to NFAT motifs in the CD3gamma gene promoter was greatly increased in the abnormal T cells. Our studies indicate that CD3gamma promoter activity can be positively influenced by NFATc1 plus NF-kappaB p50 and negatively regulated by NFATc2 containing complexes. We show that in patients' CD3(-)CD4(+) T cells, an increase in nuclear NFATc2 occurs in parallel with a decrease in NFATc1 and NF-kappaB gene expression.

CONCLUSION

Hypereosinophilic syndrome joins the growing number of pathological conditions where a defect in surface expression and/or function of the TCR/CD3 complex results from altered regulation of CD3gamma gene expression.

Recent advances in pathogenesis and management of hypereosinophilic syndromes

Idiopathic hypereosinophilic syndrome is a largely heterogeneous disorder defined until now as persistent marked hypereosinophilia of unknown origin generally complicated by end-organ damage. Recent studies clearly indicate that many patients fulfilling the diagnostic criteria of this syndrome can now be classified as presenting one of two major disease variants: the myeloproliferative or the lymphocytic variant. Research in cellular and molecular biology has provided firm evidence for the existence of discrete hematological disorders underlying these variants, questioning the pertinence of continued reference to 'idiopathic' hypereosinophilic syndrome in such patients. Furthermore, identification of these variants has a number of prognostic and therapeutic implications that must be taken into consideration for adequate management of these patients.

The hypereosinophilic syndrome revisited

Clinical and biological features of patients with the idiopathic hypereosinophilic syndrome (HES) are heterogeneous. Recent evidence suggests at least two distinct underlying hematological disorders involving myeloid and lymphoid cells, respectively. We therefore suggest that the term idiopathic should be abandoned in the classification of HES. This review defines the "myeloproliferative" and "lymphocytic" variants of the HES and addresses the management of each variant, focusing on diagnosis and treatment of the newly identified lymphocytic variant.

Immunophenotyping of Angioimmunoblastic T-Cell Lymphomas by Multiparameter Flow Cytometry

Angioimmunoblastic T-cell lymphoma (AITL) is a distinct form of peripheral T-cell lymphoma (PTCL) frequently involving lymph nodes, spleen and bone marrow, and is associated with systemic symptoms. Its histologic features may be subtle at an early phase and difficult to diagnose. Despite the success of flow cytometry (FCM) in diagnosing B-cell neoplasm, FCM has not been widely accepted as a useful method for establishing the diagnosis of PTCL. Recently, the neoplastic T-cells in AITL have been shown to express CD10. We prospectively applied multiparameter FCM immunophenotyping to three cases of histologically confirmed AITL and identified a small (5-7%) population of CD4+/CD10+ T-cells in two cases. In one case, the CD4+/CD10+ population lacked surface signals of CD3 and CD7, but strongly expressed CD2, whereas CD45 expression was very weak; partial loss of surface CD3 was observed in the other. None of the lymph nodes with reactive hyperplasia, B-cell lymphomas, or Hodgkin's lymphoma studied during the same time period contained the CD4+/CD10+ population. These findings suggest that addition of CD4/CD10 and CD3/CD10 to FCM immunophenotyping panels is useful in the diagnosis of AITL. To the best of our knowledge, this is the first report to demonstrate CD10-expressing T-cells in AITL by FCM.

Monoclonal antibody FMC7 detects a conformational epitope on the CD20 molecule: evidence from phenotyping after rituxan therapy and transfectant cell analyses

Numerous studies have reported that monoclonal antibody (mAb) FMC7 detects an antigen present on only a subset of circulating B lymphocytes. In particular, this mAb may distinguish typical B-cell chronic lymphocytic leukemia (FMC7 negative) from other types of B-cell non-Hodgkin lymphoma (B-NHL; FMC7 positive). We treated patients with B-NHL with Rituxan, a chimeric CD20 mAb, and observed abrogation of staining not only with prototype CD20 mAb B-1 but also with mAb FMC7. To investigate the relation between antigens CD20 and FMC7, we performed mutual blocking studies that showed mutual inhibition of FMC7 and CD20. In addition, FMC7 modulated CD23 expression and confirmed the presence of mAb B-1 in B-lymphoblastoid cell lines CESS and JVM. Transient transfection of myeloid cell line K562 with plasmid containing CD20-encoding cDNA produced de novo expressions of CD20 and FMC7. Our data indicate that FMC7 binds to a particular conformation of the CD20 antigen, probably to a multimeric CD20 complex. We assume that FMC7 stains positively only when CD20 antigen is present in high densities and in the postulated multimeric complex formation.