Functional Analyses of Human T Cell Extravasation in a Humanized NOD/SCID/IL2Rγcnull Transplantation Model.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2448-2448
Author(s):  
Ariane Brunk ◽  
Marion Nonn ◽  
Victoria Lang ◽  
Reinhard Henschler ◽  
Wolfgang Herr ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Skin Substitutes ◽  
Nsg Mice ◽  
Human T Cell ◽  
Human T Cells ◽  
Graft Engineering ◽  
Transplantation Model

Abstract Abstract 2448 Poster Board II-425 Donor lymphocyte graft engineering to avoid graft-versus-host (GVH) reactivity while improving graft-versus-leukemia (GVL) immunity remains of central interest in allogeneic hematopoietic stem cell transplantation (HSCT). However, appropriate models to evaluate experimental concepts of donor lymphocyte allograft engineering in vivo are missing. We, therefore, established a human-murine chimeric transplantation model using immunodeficient NOD/SCID/IL2Rγcnull (NSG) mice to evaluate GVH reactivity of human T cell grafts in vivo. Moreover, since mechanisms of immune functions resembling human GVH immunity have not yet been addressed in detail in these humanized mice we started to analyse T cell trafficking and homing to lymphoid tissues across species barrier to examine the clinical relevance of T cell activity observed in this model. To this end, skin substitutes composed of human primary allogeneic fibroblasts embedded in a collagen-based matrix were subcutaneously implanted into NSG mice to detect alloreactive specificities within the implant post adoptive transfer of MHC-mismatched or haploidentical donor T lymphocytes. The skin substitutes revealed murine vascularisation two weeks after implantation as demonstrated by immunohistological studies. Following transfer of human HLA-mismatched or haploidentical T lymphocytes, up to 23% of the T cells migrated into skin substitutes explanted 21 days post injection. As this T cell migration and homing involves both murine and human adhesion molecules we further analyzed the specific adhesion mechanisms underlying the egress of human T cells from the murine bloodstream. Using laminar flow chamber experiments and real time video recordings we could first demonstrate that human anti-CD3/anti-CD28 preactivated T lymphocytes but not naive T cells bound and firmly adhered to the murine endothelial cell line bEND.3 (BEND3.EC) at shear stresses of up to 3.5 dynes/cm2. As controls, human umbilical vein endothelial cells (HUVEC) were used. Adhesion and transmigration was significally enhanced when both human and murine endothelial cells (ECs) were prestimulated with low doses of TNF-α (5-20ng/ml) to resemble an activated phenotype. Firm adhesion of activated T lymphocytes was suppressed following pretreatment with function-blocking anti-integrin-alpha 4 (CD49d, subunit of VLA-4) or anti-integrin-alpha L (CD11a, subunit of LFA-1) antibody (Ab) or when ECs were preincubated with anti-VCAM-1 (CD106). No inhibitory effects were observed when anti-Endoglin (CD105) Ab was included as specificity control suggesting that the integrin dimer VLA-4 and its counter-receptor VCAM-1 as well as the integrin dimer LFA-1 are required for the transmigration of human T cells across murine ECs. Primary ECs derived from murine aorta are currently used to confirm our results obtained with bEND.3 cells. As the same ligand-receptor pairs are described for human T-EC interaction these findings indicate a closely related mechanism of T cell extravasation in human and murine endothelium at least in our transplantation model. In conclusion these results suggest that intravenously transferred activated human T cells migrate into allogeneic skin substitutes involving VCAM-1 and integrin-alpha-4 for firm adhesion followed by transmigration. In vivo studies investigating the effects of the function-blocking antibodies against VCAM-1 and integrin-alpha-4 in our model to confirm the in vitro results are in progress and will be reported. In addition, our human-murine chimeric NSG transplantation model may represent a promising tool to study human GVH biology and to evaluate T cell graft engineering in allogeneic HSCT. Disclosures: No relevant conflicts of interest to declare.

Generation of primary antigen-specific human cytotoxic T lymphocytes in human/mouse radiation chimera

Blood ◽  
1996 ◽  
Vol 88 (2) ◽  
pp. 721-730 ◽  
Author(s):  
H Segall ◽  
I Lubin ◽  
H Marcus ◽  
A Canaan ◽  
Y Reisner
Keyword(s):  
T Cells ◽  
T Cell ◽  
Human Lymphocytes ◽  
Scid Mice ◽  
Human Antibody ◽  
Adoptive Therapy ◽  
Activation Markers ◽  
Human T Cell ◽  
Human T Cells

Severe combined immunodeficient (SCID) mice are increasingly used as hosts for the adoptive transfer of human lymphocytes. Human antibody responses can be obtained in these xenogeneic chimeras, but information about the functionality of the human T cells in SCID mice is limited and controversial. Studies using human peripheral blood lymphocytes (PBL) injected intraperitoneally (IP) into SCID mice (hu-PBL-SCID mice) have shown that human T cells from these chimeras are anergic and have a defective signaling via the T-cell receptor. In addition, their antigenic repertoire is limited to xenoreactive clones. In the present study, we tested the functionality of human T cell in a recently described chimeric model. In this system, BALB/c mice are conditioned by irradiation and then transplanted with SCID bone marrow, followed by IP injection of human PBL. Our experiments demonstrated that human T cells, recovered from these hu-PBL-BALB mice within 1 month posttransplant, proliferated and expressed activation markers upon stimulation with anti-CD3 monoclonal antibody. A vigorous antiallogeneic human cytotoxic T-lymphocyte (CTL) response could be generated in these mice by immunizing them with irradiated allogeneic cells. Moreover, anti-human immunodeficiency virus type 1 (HIV-1) Net- specific human CTLs could be generated in vivo from naive lymphocytes by immunization of mouse-human chimeras with a recombinant vaccinia-nef virus. This model may be used to evaluate potential immunomodulatory drugs or cytokines, and could provide a relevant model for testing HIV vaccines, for production of antiviral T-cell clones for adoptive therapy, and for studying human T-cell responses in vivo.

CD27 costimulation augments the survival and antitumor activity of redirected human T cells in vivo

Blood ◽  
2012 ◽  
Vol 119 (3) ◽  
pp. 696-706 ◽  
Author(s):  
De-Gang Song ◽  
Qunrui Ye ◽  
Mathilde Poussin ◽  
Gretchen M. Harms ◽  
Mariangela Figini ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antitumor Activity ◽  
Car T Cells ◽  
Human T Cell ◽  
Human T Cells ◽  
Car T ◽  
Cd27 Costimulation

AbstractThe costimulatory effects of CD27 on T lymphocyte effector function and memory formation has been confined to evaluations in mouse models, in vitro human cell culture systems, and clinical observations. Here, we tested whether CD27 costimulation actively enhances human T-cell function, expansion, and survival in vitro and in vivo. Human T cells transduced to express an antigen-specific chimeric antigen receptor (CAR-T) containing an intracellular CD3 zeta (CD3ζ) chain signaling module with the CD27 costimulatory motif in tandem exerted increased antigen-stimulated effector functions in vitro, including cytokine secretion and cytotoxicity, compared with CAR-T with CD3ζ alone. After antigen stimulation in vitro, CD27-bearing CAR-T cells also proliferated, up-regulated Bcl-XL protein expression, resisted apoptosis, and underwent increased numerical expansion. The greatest impact of CD27 was noted in vivo, where transferred CAR-T cells with CD27 demonstrated heightened persistence after infusion, facilitating improved regression of human cancer in a xenogeneic allograft model. This tumor regression was similar to that achieved with CD28- or 4-1BB–costimulated CARs, and heightened persistence was similar to 4-1BB but greater than CD28. Thus, CD27 costimulation enhances expansion, effector function, and survival of human CAR-T cells in vitro and augments human T-cell persistence and antitumor activity in vivo.

scholarly journals Human T-cell development in SCID-hu mice: staphylococcal enterotoxins induce specific clonal deletions, proliferation, and anergy

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3144-3156 ◽  
Author(s):  
EK Waller ◽  
A Sen-Majumdar ◽  
OW Kamel ◽  
GA Hansteen ◽  
MR Schick ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
In Vivo Model ◽  
Vitro Assay ◽  
Staphylococcal Enterotoxins ◽  
Human T Cell ◽  
Human T Cells

Abstract SCID-hu mice provide an in vivo model for studying the events of normal intrathymic human T-cell development and differentiation. We injected SCID-hu mice with staphylococcal enterotoxins (SE) and determined their effects on the development and responsiveness of human T-cell populations defined by their expression of CD4 and CD8, and the type of V beta molecule in their T-cell receptors. After single intraperitoneal injections of SEB or SEE, we observed specific effects on thymic T cells expressing a cognate V beta T-cell receptor (TCR) (V beta 12.1 in the case of SEB-treated SCID-hu mice and V beta 8.1 in the case of SEE-treated mice) using both immunohistochemical staining of thymic frozen sections and flow cytometric analyses. An injection of SEB resulted in a 32% decrease in the total percentages of V beta 12.1+ cells in thymic sections after 2 days, with the greatest effect seen in the medulla, without a demonstrable effect on V beta 5.2/5.3+ or V beta 8.1+ cells. Fluorescence-activated cell sorter analysis demonstrated that TCRhi thymocytes expressing a cognate V beta TCR declined transiently by 35% to 45% 1 to 2 days after the injection of SE. Analysis of thymic subpopulations showed decreases in the TCRhi CD4+8- and CD4–8+ cells and an increase in TCRlo CD4–8+ cells. Multiple injections of SE resulted in 50% to 60% decreases in cognate V beta TCR+ CD4+8- populations. Thymocytes prepared from SE-treated SCID-hu mice demonstrated specific anergy to the SE to which they had previously been exposed in vivo, but had a normal proliferative response to other superantigens in an in vitro assay. In contrast to the effects on thymic T cells, single injections of SE resulted in a twofold increase in the total numbers of circulating CD4+8- and CD4–8+ human T cells and a fourfold to eightfold increase in T cells expressing a cognate V beta TCR. Using SE as superantigens in SCID-hu mice, we have been able to induce antigen-specific clonal deletions, anergy, and proliferation of human T cells.

scholarly journals Engineering of CD19-Specific Chimeric Antigen Receptor T Cells with the Integrin CD103 Results in Augmented Therapeutic Efficacy Against Human Lymphoma in a Preclinical Model

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2050-2050
Author(s):  
Hongxing Sun ◽  
Shan He ◽  
Lijun Meng ◽  
Ying Wang ◽  
Hanghang Zhang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chimeric Antigen Receptor ◽  
Preclinical Model ◽  
Car T Cells ◽  
Nsg Mice ◽  
Human T Cells ◽  
Car T ◽  
Human Lymphoma

Abstract Whether tumor-reactive T cells can infiltrate into the tumor to execute effector function is essential for controlling tumor growth. CD103 is an integrin protein (αE) that binds integrin β7 to form the heterodimeric integrin complex αEβ7. CD103 is important for T cell retention in peripheral tissues by interacting with E-cadherin and a promising prognosis biomarker for assessment of tumor-reactive T cells infiltrating in the tumor from various types of cancer, such as lung cancer, ovarian cancer and cervical cancers. However, CD103 is not expressed on the surface of circulating peripheral blood T cells that are genetically modified to express a chimeric antigen receptor (CAR) for adoptive T cell therapy. Whether CD103 expression on the surface of tumor-reactive CAR T cells is functionally important for their anti-tumor activity has not been previously determined. Using a preclinical model of human lymphoma expressing E-cadherin, we demonstrate that engineering of CD19-specific human CAR T cells with CD103 significantly improves their therapeutic effects on eliminating pre-established human lymphoma in immune deficient NSG mice (NOD.scid.Il2Rγcnull). We synthesized a codon optimized CD19-specific CAR containing 4-1BB and CD3zeta intracellular signaling domains (named CD19-BBz-CAR), cloned it into lentiviral vector and infected human T cells. As expected, the resultant human CD19-BBz-CAR T cells possessed potent capacity to cure human B cell leukemia in NSG mice that had been intravenously inoculated with Raji leukemic/lymphoma cells. Notably, while approximately 10% of non-CAR T cells produced high levels of CD103 from these NSG mice, CD19-BBz-CAR T cells failed to upregulate CD103, suggesting that the expression of CD19-BBz-CAR inhibits the induction of CD103 in vivo. Ex vivo assay confirmed that CD19-BBz-CAR caused dose-dependent decrease of CD103 expression in human T cells cultured in the presence of TGF-β1. This effect was mediated by the expression of costimulatory molecule 41BB, which is known essential for sustaining CD19-BBz-CAR T cells in vivo. To circumvent the repression effect of 41BB on induction of CD103, we incorporated the gene encoding integrin αE into the CAR structure to generate CD103-CD19-BBz-CAR T cells. Intriguingly, as compared to conventional CD19-BBz-CAR T cells, CD103-CD19-BBz-CAR T cells expressed high levels of CD62L and CD45RA, which resemble less differentiated T cells, produced higher levels of IL-2, which is crucial for promoting T cell expansion and function, and underwent greater expansion in cultures. Upon adoptive transfer into NSG mice that had subcutaneous human Raji lymphoma, CD103-engineering of CD19-BBz-CAR T cells dramatically decreased the distal metastasis of lymphoma, increased the infiltration of CAR T cells into the solid lymphoma, and improved the in vivo persistence of tumor-reactive CAR T cells. As a result, transfer of CD103-CD19-BBz-CAR T cells significantly increased overall survival rate of lymphoma mice compared to conventional CD19-BBz-CAR T cells (40% versus 10%, p<0.05). Our findings suggest that engineering tumor-reactive T cell with CD103 may represent a novel strategy to improve their anti-tumor efficacy. Moreover, this newly established CD103-CAR structure may have broad implication in the solid tumor treatment. Disclosures Barta: Merck, Takeda, Celgene, Seattle Genetics, Bayer: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees.

Human T-cell development in SCID-hu mice: staphylococcal enterotoxins induce specific clonal deletions, proliferation, and anergy

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3144-3156
Author(s):  
EK Waller ◽  
A Sen-Majumdar ◽  
OW Kamel ◽  
GA Hansteen ◽  
MR Schick ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
In Vivo Model ◽  
Vitro Assay ◽  
Staphylococcal Enterotoxins ◽  
Human T Cell ◽  
Human T Cells

SCID-hu mice provide an in vivo model for studying the events of normal intrathymic human T-cell development and differentiation. We injected SCID-hu mice with staphylococcal enterotoxins (SE) and determined their effects on the development and responsiveness of human T-cell populations defined by their expression of CD4 and CD8, and the type of V beta molecule in their T-cell receptors. After single intraperitoneal injections of SEB or SEE, we observed specific effects on thymic T cells expressing a cognate V beta T-cell receptor (TCR) (V beta 12.1 in the case of SEB-treated SCID-hu mice and V beta 8.1 in the case of SEE-treated mice) using both immunohistochemical staining of thymic frozen sections and flow cytometric analyses. An injection of SEB resulted in a 32% decrease in the total percentages of V beta 12.1+ cells in thymic sections after 2 days, with the greatest effect seen in the medulla, without a demonstrable effect on V beta 5.2/5.3+ or V beta 8.1+ cells. Fluorescence-activated cell sorter analysis demonstrated that TCRhi thymocytes expressing a cognate V beta TCR declined transiently by 35% to 45% 1 to 2 days after the injection of SE. Analysis of thymic subpopulations showed decreases in the TCRhi CD4+8- and CD4–8+ cells and an increase in TCRlo CD4–8+ cells. Multiple injections of SE resulted in 50% to 60% decreases in cognate V beta TCR+ CD4+8- populations. Thymocytes prepared from SE-treated SCID-hu mice demonstrated specific anergy to the SE to which they had previously been exposed in vivo, but had a normal proliferative response to other superantigens in an in vitro assay. In contrast to the effects on thymic T cells, single injections of SE resulted in a twofold increase in the total numbers of circulating CD4+8- and CD4–8+ human T cells and a fourfold to eightfold increase in T cells expressing a cognate V beta TCR. Using SE as superantigens in SCID-hu mice, we have been able to induce antigen-specific clonal deletions, anergy, and proliferation of human T cells.

scholarly journals Synthetic mycobacterial diacyl trehaloses reveal differential recognition by human T cell receptors and the C-type lectin Mincle

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Josephine F. Reijneveld ◽  
Mira Holzheimer ◽  
David C. Young ◽  
Kattya Lopez ◽  
Sara Suliman ◽  
...  
Keyword(s):  
T Cells ◽  
Fatty Acid ◽  
Immune System ◽  
T Cell ◽  
Cross Reactivity ◽  
Lipid Binding ◽  
Human Immune System ◽  
Human T Cell ◽  
Human T Cells ◽  
Pure Compounds

AbstractThe cell wall of Mycobacterium tuberculosis is composed of diverse glycolipids which potentially interact with the human immune system. To overcome difficulties in obtaining pure compounds from bacterial extracts, we recently synthesized three forms of mycobacterial diacyltrehalose (DAT) that differ in their fatty acid composition, DAT1, DAT2, and DAT3. To study the potential recognition of DATs by human T cells, we treated the lipid-binding antigen presenting molecule CD1b with synthetic DATs and looked for T cells that bound the complex. DAT1- and DAT2-treated CD1b tetramers were recognized by T cells, but DAT3-treated CD1b tetramers were not. A T cell line derived using CD1b-DAT2 tetramers showed that there is no cross-reactivity between DATs in an IFN-γ release assay, suggesting that the chemical structure of the fatty acid at the 3-position determines recognition by T cells. In contrast with the lack of recognition of DAT3 by human T cells, DAT3, but not DAT1 or DAT2, activates Mincle. Thus, we show that the mycobacterial lipid DAT can be both an antigen for T cells and an agonist for the innate Mincle receptor, and that small chemical differences determine recognition by different parts of the immune system.

627 The DLL3-targeted half-life extended bispecific T cell engager (HLE BiTE®) immune-oncology therapy AMG 757 has potent antitumor activity in neuroendocrine cancer

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A663-A663
Author(s):  
Keegan Cooke ◽  
Juan Estrada ◽  
Jinghui Zhan ◽  
Jonathan Werner ◽  
Fei Lee ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Mouse Models ◽  
T Cell Activation ◽  
Phase 1 ◽  
Phase 1 Study ◽  
Human T Cells

BackgroundNeuroendocrine tumors (NET), including small cell lung cancer (SCLC), have poor prognosis and limited therapeutic options. AMG 757 is an HLE BiTE® immune therapy designed to redirect T cell cytotoxicity to NET cells by binding to Delta-like ligand 3 (DLL3) expressed on the tumor cell surface and CD3 on T cells.MethodsWe evaluated activity of AMG 757 in NET cells in vitro and in mouse models of neuroendocrine cancer in vivo. In vitro, co-cultures of NET cells and human T cells were treated with AMG 757 in a concentration range and T cell activation, cytokine production, and tumor cell killing were assessed. In vivo, AMG 757 antitumor efficacy was evaluated in xenograft NET and in orthotopic models designed to mimic primary and metastatic SCLC lesions. NSG mice bearing established NET were administered human T cells and then treated once weekly with AMG 757 or control HLE BiTE molecule; tumor growth inhibition was assessed. Pharmacodynamic effects of AMG 757 in tumors were also evaluated in SCLC models following a single administration of human T cells and AMG 757 or control HLE BiTE molecule.ResultsAMG 757 induced T cell activation, cytokine production, and potent T cell redirected killing of DLL3-expressing SCLC, neuroendocrine prostate cancer, and other DLL3-expressing NET cell lines in vitro. AMG 757-mediated redirected lysis was specific for DLL3-expressing cells. In patient-derived xenograft and orthotopic models of SCLC, single-dose AMG 757 effectively engaged human T cells administered systemically, leading to a significant increase in the number of human CD4+ and CD8+ T cells in primary and metastatic tumor lesions. Weekly administration of AMG 757 induced significant tumor growth inhibition of SCLC (figure 1) and other NET, including complete regression of established tumors and clearance of metastatic lesions. These findings warranted evaluation of AMG 757 (NCT03319940); the phase 1 study includes dose exploration (monotherapy and in combination with pembrolizumab) and dose expansion (monotherapy) in patients with SCLC (figure 2). A study of AMG 757 in patients with neuroendocrine prostate cancer is under development based on emerging data from the ongoing phase 1 study.Abstract 627 Figure 1AMG 757 Significantly reduced tumor growth in orthotopic SCLC mouse modelsAbstract 627 Figure 2AMG 757 Phase 1 study designConclusionsAMG 757 engages and activates T cells to kill DLL3-expressing SCLC and other NET cells in vitro and induces significant antitumor activity against established xenograft tumors in mouse models. These preclinical data support evaluation of AMG 757 in clinical studies of patients with NET.Ethics ApprovalAll in vivo work was conducted under IACUC-approved protocol #2009-00046.

scholarly journals In Vivo Selection of T-Cell Receptor Junctional Region Sequences by HLA-A2 Human T-Cell Lymphotropic Virus Type 1 Tax11-19 Peptide Complexes

2001 ◽  
Vol 75 (2) ◽  
pp. 1065-1071 ◽  
Author(s):  
Mineki Saito ◽  
Graham P. Taylor ◽  
Akiko Saito ◽  
Yoshitaka Furukawa ◽  
Koichiro Usuku ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Virus Type ◽  
Cell Receptor ◽  
Antigen Specificity ◽  
Human T Cell ◽  
Cdr3 Region

ABSTRACT Using HLA-peptide tetrameric complexes, we isolated human T-cell lymphotrophic virus type 1 Tax peptide-specific CD8+ T cells ex vivo. Antigen-specific amino acid motifs were identified in the T-cell receptor Vβ CDR3 region of clonally expanded CD8+ T cells. This result directly confirms the importance of the CDR3 region in determining the antigen specificity in vivo.

scholarly journals AAV-Mediated In Vivo CAR Gene Therapy for Targeting Human T Cell Leukemia

2021 ◽  
Author(s):  
Waqas Nawaz ◽  
Bilian Huang ◽  
Shijie Xu ◽  
Yanlei Li ◽  
Linjing Zhu ◽  
...  
Keyword(s):  
Gene Therapy ◽  
T Cells ◽  
T Cell ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Car T Cells ◽  
Car T Cell ◽  
Human T Cell ◽  
Car T

AbstractChimeric antigen receptor (CAR) T cell therapy is the most active field in immuno-oncology and brings substantial benefit to patients with B cell malignancies. However, the complex procedure for CAR T cell generation hampers its widespread applications. Here, we describe a novel approach in which human CAR T cells can be generated within the host upon injecting an Adeno-associated virus (AAV)vector carrying the CAR gene, which we call AAV delivering CAR gene therapy (ACG). Upon single infusion into a humanized NCG tumor mouse model of human T cell leukemia, AAV generates sufficient numbers of potent in vivo CAR cells, resulting in tumor regression; these in vivo generated CAR cells produce antitumor immunological characteristics. This instantaneous generation of in vivo CAR T cells may bypass the need for patient lymphodepletion, as well as the ex vivo processes of traditional CAR T cell production, which may make CAR therapy simpler and less expensive. It may allow the development of intricate, individualized treatments in the form of on-demand and diverse therapies.Significance StatementAAV can generate enough CAR cells within the host. That act as a living drug, distributed throughout the body, and persist for weeks, with the ability to recognize and destroy tumor cells.

scholarly journals Tax and Overlapping Rex Sequences Do Not Confer the Distinct Transformation Tropisms of Human T-Cell Leukemia Virus Types 1 and 2

2003 ◽  
Vol 77 (14) ◽  
pp. 7728-7735 ◽  
Author(s):  
Jianxin Ye ◽  
Li Xie ◽  
Patrick L. Green
Keyword(s):  
T Cells ◽  
T Cell ◽  
Leukemia Virus ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
T Cell Leukemia Virus

ABSTRACT Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are distinct oncogenic retroviruses that infect several cell types but display their biological and pathogenic activity only in T cells. Previous studies have indicated that in vivo HTLV-1 has a preferential tropism for CD4+ T cells, whereas HTLV-2 in vivo tropism is less clear but appears to favor CD8+ T cells. Both CD4+ and CD8+ T cells are susceptible to HTLV-1 and HTLV-2 infection in vitro, and HTLV-1 has a preferential immortalization and transformation tropism of CD4+ T cells, whereas HTLV-2 immortalizes and transforms primarily CD8+ T cells. The molecular mechanism that determines this tropism of HTLV-1 and HTLV-2 has not been determined. HTLV-1 and HTLV-2 carry the tax and rex transregulatory genes in separate but partially overlapping reading frames. Since Tax has been shown to be critical for cellular transformation in vitro and interacts with numerous cellular processes, we hypothesized that the viral determinant of transformation tropism is encoded by tax. Using molecular clones of HTLV-1 (Ach) and HTLV-2 (pH6neo), we constructed recombinants in which tax and overlapping rex genes of the two viruses were exchanged. p19 Gag expression from proviral clones transfected into 293T cells indicated that both recombinants contained functional Tax and Rex but with significantly altered activity compared to the wild-type clones. Stable transfectants expressing recombinant viruses were established, irradiated, and cocultured with peripheral blood mononuclear cells. Both recombinants were competent to transform T lymphocytes with an efficiency similar to that of the parental viruses. Flow cytometry analysis indicated that HTLV-1 and HTLV-1/TR2 had a preferential tropism for CD4+ T cells and that HTLV-2 and HTLV-2/TR1 had a preferential tropism for CD8+ T cells. Our results indicate that tax/rex in different genetic backgrounds display altered functional activity but ultimately do not contribute to the different in vitro transformation tropisms. This first study with recombinants between HTLV-1 and HTLV-2 is the initial step in elucidating the different pathobiologies of HTLV-1 and HTLV-2.

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