scholarly journals The expression of CD26 and CD40 ligand is mutually exclusive in human T- cell non-Hodgkin's lymphomas/leukemias

Blood ◽  
1995 ◽  
Vol 86 (12) ◽  
pp. 4617-4626 ◽  
Author(s):  
A Carbone ◽  
A Gloghini ◽  
V Zagonel ◽  
D Aldinucci ◽  
V Gattei ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Mycosis Fungoides ◽  
Cell Lines ◽  
Critical Role ◽  
Cd40 Ligand ◽  
T Cell Lymphomas ◽  
Human T Cell ◽  
Hodgkin's Lymphomas

CD26 and CD40 ligand (CD40L) are surface molecules on human activated T lymphocytes that play a critical role in the regulation of lymphopoiesis. Both molecules are expressed on a restricted fraction of human T-cell non-Hodgkin's lymphomas (NHL)/leukemias; however, little is known about their functional and/or clinical significance in these disorders. In this study, the pattern of expression of CD40L was compared with that of the CD26 molecule. A series of 67 human T-cell NHL/leukemias and a panel of leukemia/lymphoma T-cell lines were evaluated by immunohistochemistry, flow cytometry, and RNA studies. The overall frequency of CD26+ and CD40L+ samples was rather similar (25/67 [37%] v 18/67 [27%]). However, the majority of CD26-expressing cases clustered in the lymphoblastic lymphomas (LBL)/T-acute lymphoblastic leukemias (ALL; 12/23) and CD30+ anaplastic large-cell (ALC) lymphomas (5/8), whereas CD40L+ lymphomas included a large fraction of mycosis fungoides (11/21 [52%]). CD26 and CD40L coexpression was found only in 2 myocosis fungoides cases and 1 small lymphocytic lymphoma. Thus, the expression of the two antigens was mutually exclusive in almost all T- cell lymphomas/leukemias. Accordingly, lymphoma cell lines expressed either one of the molecules or the relative amounts of CD26 and CD40L were inversely proportional. In contrast, reactive T lymphocytes from patients with non-neoplastic T-cell expansions and in vitro activated CD3+ or CD4+ normal T cells were found to coexpress CD40L and CD26. Results of a multivariate analysis showed that the expression of CD26 in T-cell LBL/ALL patients was associated to a worse outcome in terms of survival, as compared with patients with CD26- tumors (P < or = .0001). Based on our results, it can be concluded that, (1) as opposed to activated or reactive normal T cells, the expression of CD26 and of CD40L is mutually exclusive in human T-cell lymphomas/leukemias; (2) expression of CD26 is restricted to aggressive pathologic entities, such as T-cell LBL/ALL and T-cell CD30+ ALC lymphomas, whereas CD40L is expressed on slow progressing diseases such as mycosis fungoides; and (3) within the T-cell LBL/ALL group of tumors, CD26 may identify a subset of poor prognosis patients.

scholarly journals An overview of cutaneous T cell lymphomas

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 1882 ◽  
Author(s):  
Nooshin Bagherani ◽  
Bruce R. Smoller
Keyword(s):  
T Cell ◽  
T Lymphocytes ◽  
Mycosis Fungoides ◽  
Annual Incidence ◽  
Heterogeneous Group ◽  
Not Otherwise Specified ◽  
T Cell Lymphomas ◽  
Hodgkin's Lymphomas ◽  
Diagnosis Therapy ◽  
Peripheral T Cell Lymphomas

Cutaneous T cell lymphomas (CTCLs) are a heterogeneous group of extranodal non-Hodgkin’s lymphomas that are characterized by a cutaneous infiltration of malignant monoclonal T lymphocytes. They typically afflict adults with a median age of 55 to 60 years, and the annual incidence is about 0.5 per 100,000. Mycosis fungoides, Sézary syndrome, and primary cutaneous peripheral T cell lymphomas not otherwise specified are the most important subtypes of CTCL. CTCL is a complicated concept in terms of etiopathogenesis, diagnosis, therapy, and prognosis. Herein, we summarize advances which have been achieved in these fields.

scholarly journals CD2-mediated autocrine growth of herpes virus saimiri-transformed human T lymphocytes.

1992 ◽  
Vol 176 (3) ◽  
pp. 909-913 ◽  
Author(s):  
H W Mittrücker ◽  
I Müller-Fleckenstein ◽  
B Fleckenstein ◽  
B Fleischer
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cell Lines ◽  
Herpes Virus ◽  
Interleukin 2 ◽  
Critical Event ◽  
Autocrine Growth ◽  
Human T Cell ◽  
Herpès Virus

Herpes virus saimiri (HVS) immortalizes T lymphocytes from a variety of primates and causes acute T cell lymphomas and leukemias in nonnatural primate hosts. Here we have analyzed the requirements for growth of three HVS-transformed human T cell lines. The cells expressed the phenotype of activated T cells: two were CD4+, and one was CD8+. All three cells responded to all allogeneic human cell lines tested with enhanced proliferation, production of interleukin 2 (IL-2), and increased expression of the IL-2 receptor. Binding of CD2 to its ligand CD58 was the critical event mediating stimulation because: (a) monoclonal antibodies (mAbs) to CD2 and to CD58, but not to a variety of other surface structures, blocked induced and spontaneous proliferation and IL-2 production; (b) only anti-CD2 mAbs were stimulatory if crosslinked; (c) a nonstimulatory cell was rendered stimulatory by CD58 transfection; and (d) the cells responded specifically to CD58 on sheep red blood cells. Growth of the cells required activation because cyclosporin A and FK506 blocked stimulator cell-induced IL-2 production and proliferation as well as the spontaneous growth of the lines. Antibodies to the IL-2 receptor reduced proliferation of the cells and blocked IL-2 utilization. Taken together, these results show that HVS-transformed T cells proliferate in response to CD2-mediated contact with stimulator cells or with each other in an IL-2-dependent fashion. They suggest that HVS transforms human T cells to an activation-dependent autocrine growth.

scholarly journals Cutaneous T-cell lymphomas: modern data of pathogenesis, clinics and therapy

2018 ◽  
Vol 13 (3) ◽  
pp. 25-38
Author(s):  
O. M. Demina ◽  
O. E. Akilov ◽  
A. G. Rumyantsev
Keyword(s):  
T Cell ◽  
T Lymphocytes ◽  
Mycosis Fungoides ◽  
Lymphoproliferative Diseases ◽  
Complex Concept ◽  
T Cell Lymphomas ◽  
Skin Infiltration ◽  
Hodgkin's Lymphomas ◽  
Diagnosis Therapy ◽  
Summary Data

Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of extranodal non-Hodgkin’s lymphomas that are characterized by skin infiltration with malignant monoclonal T lymphocytes. More common in adults aged 55 to 60 years, the annual incidence is about 0.5 per 100 000 people. Mycosis fungoides, Sézary syndrome and CD30+ lymphoproliferative diseases are the main subtypes of CTCL. To date, CTCL have a complex concept of etiopathogenesis, diagnosis, therapy and prognosis. The article presented summary data on these issues.

IGF-1 down-regulates IFN-γR2 chain surface expression and desensitizes IFN-γ/STAT-1 signaling in human T lymphocytes

Blood ◽  
2003 ◽  
Vol 102 (8) ◽  
pp. 2933-2939 ◽  
Author(s):  
Paola Bernabei ◽  
Marita Bosticardo ◽  
Giuliana Losana ◽  
Gabriella Regis ◽  
Francesca Di Paola ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cell Lines ◽  
Critical Role ◽  
Constitutive Expression ◽  
Myeloid Cell ◽  
Surface Expression ◽  
Ifn Γ ◽  
T Cell Lines

Abstract The ability of insulin-like growth factor-1 (IGF-1) to regulate surface expression of the interferon-γ receptor 2 (IFN-γR2) transducing chain and activation of IFN-γ–induced signal transducer and activator of transcription-1 (STAT-1) in human T cells was analyzed. We show that, especially in the absence of serum (which contains IGF-1), IGF-1 down-regulated surface expression of the IFN-γR2 chain and inhibited both IFN-γ–dependent STAT-1 activation and apoptosis in T-cell lines ST4, Jurkat, and Molt-4. IFN-γR2 down-regulation resulted from its enhanced internalization since IGF-1 completely restored the uptake of anti–IFN-γR2 monoclonal antibody (mAb) in serum-deprived T-cell lines. When the interaction between IGF-1 and its receptor was blocked by anti–IGF-1R mAb, enhancement of IFN-γR2 surface expression, STAT-1 activation, and reinstatement of IFN-γ–induced apoptosis were observed. Enhanced expression of IFN-γR2 was also observed in phytohemagglutinin (PHA)–activated T lymphoblasts cultured in the presence of anti–IGF-1R mAb, whereas IGF-1 or anti–IGF-1R mAb did not modify the high IFN-γR2 expression in B and myeloid cell lines. Both IGF-1 and anti–IGF-1R mAb did not modify the constitutive expression of IFN-γR2 mRNA in T cells as well as the high IFN-γR1 binding chain surface expression in T, B, and myeloid cells. These data indicate that IGF-1 plays a critical role in the desensitization of IFN-γ/STAT-1 signaling in T lymphocytes by delivering a signal for IFN-γR2 internalization.

scholarly journals Human mature T cells that are anergic in vivo prevail in SCID mice reconstituted with human peripheral blood.

1992 ◽  
Vol 175 (2) ◽  
pp. 503-516 ◽  
Author(s):  
M Tary-Lehmann ◽  
A Saxon
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Lines ◽  
Peripheral Blood ◽  
Human Peripheral Blood ◽  
Critical Role ◽  
Scid Mice ◽  
Human T Cell ◽  
Human T Cells ◽  
T Cell Lines

In these studies we have characterized the human cells that repopulate severe combined immunodeficient (SCID) mice after injection of adult peripheral blood or cord blood (hu-PBL-SCID mice). In all organs of the chimeras, and at any time point tested, single-positive (CD4+ or CD8+) T cells that expressed the alpha/beta T cell receptor (TCR) prevailed. All T cells were CD45RO+ and the majority were also HLA-DR+. Thus, the human T cells in the chimeras exhibited the phenotype of mature, memory cells that showed signs of recent activation. Cell cycle studies revealed a mitotically active human T cell population in the murine host. However, when freshly isolated from the chimeras, the human T cells were refractory to stimulation by anti-CD3 antibody but proliferated in response to exogenous interleukin 2. Chimera-derived human T cell lines retained this state of unresponsiveness to TCR-triggered proliferation for 4-6 wk in vitro. Subsequently, the T cell lines developed responses to anti-CD3 stimulation and 9 of 11 of the lines also proliferated in response to splenic stimulator cells of SCID mice. These data demonstrate that the human T cells are in a state of reversible anergy in the murine host and that xenoreactivity might play a critical role in hu-PBL-SCID mice. Mechanisms that may determine repopulation of SCID mice with human peripheral blood mononuclear cells are discussed.

scholarly journals Epiligrin, a component of epithelial basement membranes, is an adhesive ligand for alpha 3 beta 1 positive T lymphocytes.

1993 ◽  
Vol 121 (5) ◽  
pp. 1141-1152 ◽  
Author(s):  
E A Wayner ◽  
S G Gil ◽  
G F Murphy ◽  
M S Wilke ◽  
W G Carter
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Basement Membrane ◽  
B Cell ◽  
Cell Lines ◽  
B Cell Lymphoma ◽  
Lymphokine Activated Killer Cells ◽  
Cutaneous Inflammation ◽  
Epidermal Basement Membrane

The cutaneous T cell lymphomas (CTCL), typified by mycosis fungoides, and several chronic T cell mediated dermatoses are characterized by the migration of T lymphocytes into the epidermis (epidermotropism). Alternatively, other types of cutaneous inflammation (malignant cutaneous B cell lymphoma, CBCL, or lymphocytoma cutis, non-malignant T or B cell type) do not show evidence of epidermotropism. This suggests that certain T lymphocyte subpopulations are able to interact with and penetrate the epidermal basement membrane. We show here that T lymphocytes derived from patients with CTCL (HUT 78 or HUT 102 cells), adhere to the detergent-insoluble extracellular matrix prepared from cultured basal keratinocytes (HFK ECM). HUT cell adhesion to HFK ECM was inhibitable with monoclonal antibodies (mAbs) directed to the alpha 3 (P1B5) or beta 1 (P4C10) integrin receptors, and could be up-regulated by an activating anti-beta 1 mAb (P4G11). An inhibitory mAb, P3H9-2, raised against keratinocytes identified epiligrin as the ligand for alpha 3 beta 1 positive T cells in HFK ECM. Interestingly, two lymphocyte populations could be clearly distinguished relative to expression of alpha 3 beta 1 by flow cytometry analysis. Lymphokine activated killer cells, alloreactive cytotoxic T cells and T cells derived from patients with CTCL expressed high levels of alpha 3 beta 1 (alpha 3 beta 1high). Non-adherent peripheral blood mononuclear cells, acute T or B lymphocytic leukemias, or non-cutaneous T or B lymphocyte cell lines expressed low levels of alpha 3 beta 1 (alpha 3 beta 1low). Resting PBL or alpha 3 beta 1low T or B cell lines did not adhere to HFK ECM or purified epiligrin. However, adhesion to epiligrin could be up-regulated by mAbs which activate the beta 1 subunit indicating that alpha 3 beta 1 activity is a function of expression and affinity. In skin derived from patients with graft-vs.-host (GVH) disease, experimentally induced delayed hypersensitivity reactions, and CTCL, the infiltrating T cells could be stained with mAbs to alpha 3 or beta 1 and were localized in close proximity to the epiligrin-containing basement membrane. Infiltrating lymphocytes in malignant cutaneous B disease (CBCL) did not express alpha 3 beta 1 by immunohistochemical techniques and did not associate with the epidermal basement membrane. The present findings clearly define a function for alpha 3 beta 1 in T cells and strongly suggest that alpha 3 beta 1 interaction with epiligrin may be involved in the pathogenesis of cutaneous inflammation.

Structure of the two promoters of the human lck gene: differential accumulation of two classes of lck transcripts in T cells

1989 ◽  
Vol 9 (5) ◽  
pp. 2173-2180
Author(s):  
T Takadera ◽  
S Leung ◽  
A Gernone ◽  
Y Koga ◽  
Y Takihara ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Lines ◽  
Carcinoma Cell ◽  
Human Peripheral Blood ◽  
Specific Gene ◽  
Type I ◽  
Type Ii ◽  
Carcinoma Cell Lines ◽  
Human T Cell

The human T-cell- or lymphocyte-specific gene, lck, encodes a tyrosine kinase and is a member of the src family. In this report we demonstrate that there are two classes of human lck transcripts (types I and II), containing different 5'-untranslated regions, which are expressed from two distinct promoters. No apparent sequence similarity was observed between the 5'-flanking regions of the two promoters. The expression of lck in human T-cell leukemia and carcinoma cell lines and in human peripheral blood T lymphocytes was examined by S1 nuclease and primer extension mapping and by Northern (RNA) blot analysis of total cellular RNA. The following results were obtained. (i) Two RNA start sites in the downstream promoter were used to generate type I transcripts. (ii) The major human type I start site has not been described for the mouse. (iii) At least five RNA start sites in the upstream promoter were used to generate type II transcripts. (iv) In T cells and in two colon carcinoma cell lines, type II transcripts were present in higher amounts than type I transcripts. (v) In T cells treated with phytohemagglutinin, tetradecanoylphorbol acetate, and cyclosporin A, the modulation of lck expression was associated primarily with changes in levels of type II transcripts. The above results suggest that the two human lck promoters are utilized differentially and may be regulated independently during certain physiological states.

scholarly journals A Novel Approach for Treatment of T-Cell Malignancies: Targeting T-Cell Receptor Vβ Families

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 28-29
Author(s):  
Jie Wang ◽  
Katarzyna Urbanska ◽  
Prannda Sharma ◽  
Mathilde Poussin ◽  
Reza Nejati ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Cell Receptor ◽  
Brentuximab Vedotin ◽  
T Cell Lymphomas ◽  
T Cell Malignancies

Background: Peripheral T-cell lymphomas (PTCL) encompass a highly heterogeneous group of T-cell malignancies and are generally associated with a poor prognosis. Combination chemotherapy results in consistently poorer outcomes for T-cell lymphomas compared with B-cell lymphomas.1 There is an urgent clinical need to develop novel approaches to treatment of PTCL. While CD19- and CD20-directed immunotherapies have been successful in the treatment of B-cell malignancies, T-cell malignancies lack suitable immunotherapeutic targets. Brentuximab Vedotin, a CD30 antibody-drug conjugate, is not applicable to PTCL subtypes which do not express CD30.2 Broadly targeting pan-T cell markers is predicted to result in extensive T-cell depletion and clinically significant immune deficiency; therefore, a more tumor-specific antigen that primarily targets the malignant T-cell clone is needed. We reasoned that since malignant T cells are clonal and express the same T-cell receptor (TCR) in a given patient, and since the TCR β chain in human α/β TCRs can be grouped into 24 functional Vβ families targetable by monoclonal antibodies, immunotherapeutic targeting of TCR Vβ families would be an attractive strategy for the treatment of T-cell malignancies. Methods: We developed a flexible approach for targeting TCR Vβ families by engineering T cells to express a CD64 chimeric immune receptor (CD64-CIR), comprising a CD3ζ T cell signaling endodomain, CD28 costimulatory domain, and the high-affinity Fc gamma receptor I, CD64. T cells expressing CD64-CIR are predicted to be directed to tumor cells by Vβ-specific monoclonal antibodies that target tumor cell TCR, leading to T cell activation and induction of tumor cell death by T cell-mediated cytotoxicity. Results: This concept was first evaluated in vitro using cell lines. SupT1 T-cell lymphoblasts, which do not express a native functioning TCR, were stably transduced to express a Vβ12+ MART-1 specific TCR, resulting in a Vβ12 TCR expressing target T cell line.3 Vβ family specific cytolysis was confirmed by chromium release assays using co-culture of CD64 CIR transduced T cells with the engineered SupT1-Vβ12 cell line in the presence of Vβ12 monoclonal antibody. Percent specific lysis was calculated as (experimental - spontaneous lysis / maximal - spontaneous lysis) x 100. Controls using no antibody, Vβ8 antibody, and untransduced T cells did not show significant cytolysis (figure A). Next, the Jurkat T cell leukemic cell line, which expresses a native Vβ8 TCR, was used as targets in co-culture. Again, Vβ family target specific cytolysis was achieved in the presence of CD64 CIR T cells and Vβ8, but not Vβ12 control antibody. Having demonstrated Vβ family specific cytolysis in vitro using target T cell lines, we next evaluated TCR Vβ family targeting in vivo. Immunodeficient mice were injected with SupT1-Vβ12 or Jurkat T cells with the appropriate targeting Vβ antibody, and either CD64 CIR T cells or control untransduced T cells. The cell lines were transfected with firefly luciferase and tumor growth was measured by bioluminescence. The CD64 CIR T cells, but not untransduced T cells, in conjunction with the appropriate Vβ antibody, successfully controlled tumor growth (figure B). Our results provide proof-of-concept that TCR Vβ family specific T cell-mediated cytolysis is feasible, and informs the development of novel immunotherapies that target TCR Vβ families in T-cell malignancies. Unlike approaches that target pan-T cell antigens, this approach is not expected to cause substantial immune deficiency and could lead to a significant advance in the treatment of T-cell malignancies including PTCL. References 1. Coiffier B, Brousse N, Peuchmaur M, et al. Peripheral T-cell lymphomas have a worse prognosis than B-cell lymphomas: a prospective study of 361 immunophenotyped patients treated with the LNH-84 regimen. The GELA (Groupe d'Etude des Lymphomes Agressives). Ann Oncol Off J Eur Soc Med Oncol. 1990;1(1):45-50. 2. Horwitz SM, Advani RH, Bartlett NL, et al. Objective responses in relapsed T-cell lymphomas with single agent brentuximab vedotin. Blood. 2014;123(20):3095-3100. 3. Hughes MS, Yu YYL, Dudley ME, et al. Transfer of a TCR Gene Derived from a Patient with a Marked Antitumor Response Conveys Highly Active T-Cell Effector Functions. Hum Gene Ther. 2005;16(4):457-472. Figure Disclosures Schuster: Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding; AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria.

Activation of interleukin-13 expression in T cells from HTLV-1-infected individuals and in chronically infected cell lines

Blood ◽  
2003 ◽  
Vol 102 (12) ◽  
pp. 4130-4136 ◽  
Author(s):  
Hye-Kyung Chung ◽  
Howard A. Young ◽  
Peter K. C. Goon ◽  
Gisela Heidecker ◽  
Gerald L. Princler ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Infected Cell ◽  
Cell Lines ◽  
Regulatory Protein ◽  
Immunofluorescent Staining ◽  
Cell Leukemia Virus Type ◽  
Interleukin 13 ◽  
Human T Cell ◽  
T Cell Lines

Abstract Human T-cell leukemia virus type 1 (HTLV-1) infection profoundly alters T-cell gene expression, and the dysregulated synthesis of cytokines could influence the course and pathologic consequences of infection. In the process of screening T-cell lines for T helper 1 (Th1) and Th2 cytokine mRNAs, we observed that interleukin-13 (IL-13) mRNA was highly expressed in HTLV-1-infected, IL-2-dependent T-cell lines. IL-9 and interferon gamma (IFN-γ) mRNAs were also expressed at high levels in chronically infected cell lines. IL-5 mRNA was detected in 60% of the HTLV-1-infected cell lines, but mRNAs for IL-4, IL-10, IL-2, and IL-15 were either below detection limits or did not correlate with HTLV-1 infection. Transcriptional activation of the IL-13 promoter by the HTLV-1 Tax trans-regulatory protein was demonstrated in Jurkat T cells transiently transfected with an IL-13 promoter-reporter plasmid. The clinical relevance of these observations was demonstrated by immunofluorescent staining and flow cytometry of lymphocytes obtained from HTLV-1-infected patients. These studies revealed that IL-13 production was directly related to the level of Tax expression in the infected CD4+ T cells soon after in vitro culture. As IL-13 plays key roles in tumor immunosurveillance, asthma, and central nervous system inflammation, it may contribute to the pathophysiology of HTLV-1-associated diseases. (Blood. 2003;102:4130-4136)

scholarly journals Phenotypic and functional characterization of T-BAM (CD40 ligand)+ T- cell non-Hodgkin's lymphoma

Blood ◽  
1994 ◽  
Vol 84 (3) ◽  
pp. 866-872 ◽  
Author(s):  
G Inghirami ◽  
S Lederman ◽  
MJ Yellin ◽  
A Chadburn ◽  
L Chess ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Functional Characterization ◽  
Cd40 Ligand ◽  
B Cell Differentiation ◽  
Helper Function ◽  
Unique Distribution ◽  
Hodgkin's Lymphomas

Abstract The precise mechanisms regulating T-helper function have been intensively investigated. We and others have recently identified a new T-cell-B-cell-activating molecule called T-BAM that directs B-cell differentiation by interacting with the CD40 molecule on B cells. Using a specific monoclonal antibody against T-BAM (5C8), we have previously shown that T-BAM expressing T cells are predominantly CD4+CD8- and in normal lymphoid tissue have a unique distribution. However, no information has been obtained regarding the phenotype and functional properties of human neoplastic T cells. Therefore, we investigated T- BAM expression immunohistochemically in 87 well-characterized T-cell non-Hodgkin's lymphomas and lymphoid leukemias (LL). We found that 21/81 neoplasms expressed detectable T-BAM and these positive tumors belong almost exclusively to the CD4+CD8- subtype. In addition, to determine whether T-BAM expression could be induced on T-BAM-LL cells, we activated T-BAM-LLs in vitro and showed that T-BAM could be upregulated only in CD4+CD8- tumors. Our studies clearly show that T- BAM is constitutively expressed in a large number of T-cell neoplasms with a relative mature phenotype (CD4+CD8-) and that only CD4+ neoplastic T cells can be induced in vitro to express this molecule. Additional studies are necessary to identify the biologic significance of T-BAM expression and its potential and clinical implications.

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