Human T Cell Development and HIV Infection in Human Hemato-Lymphoid System Mice

The fate and numbers of hematopoietic stem cells (HSC) and their progeny that seed the thymus constitute a fundamental question with important clinical implications. HSC transplantation is often complicated by limited T-cell reconstitution, especially when HSC from umbilical cord blood are used. Attempts to improve immune reconstitution have until now been unsuccessful, underscoring the need for better insight into thymic reconstitution. Here we made use of the NOD-SCID-IL-2Rγ−/− xenograft model and lentiviral cellular barcoding of human HSCs to study T-cell development in the thymus at a clonal level. Barcoded HSCs showed robust (>80% human chimerism) and reproducible myeloid and lymphoid engraftment, with T cells arising 12 wk after transplantation. A very limited number of HSC clones (<10) repopulated the xenografted thymus, with further restriction of the number of clones during subsequent development. Nevertheless, T-cell receptor rearrangements were polyclonal and showed a diverse repertoire, demonstrating that a multitude of T-lymphocyte clones can develop from a single HSC clone. Our data imply that intrathymic clonal fitness is important during T-cell development. As a consequence, immune incompetence after HSC transplantation is not related to the transplantation of limited numbers of HSC but to intrathymic events.

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LMO2 and TAL1 Cooperate in a Model of Human T−Cell Leukemogenesis.

Blood ◽

10.1182/blood.v108.11.773.773 ◽

2006 ◽

Vol 108 (11) ◽

pp. 773-773

Author(s):

James A. Kennedy ◽

Frederic Barabe ◽

John E. Dick

Keyword(s):

T Cell ◽

T Cell Development ◽

Cell Development ◽

Early Event ◽

Aberrant Expression ◽

Human T Cell ◽

Differentiation Block ◽

Population Doublings ◽

T Cell Leukemogenesis ◽

T Lymphopoiesis

Abstract T−cell acute lymphoblastic leukemia (T−ALL) is associated with the aberrant expression of a limited number of genes, including the basic helix−loop−helix transcription factor TAL1 (SCL) and the LIM−only domain gene LMO2, in the T−cell lineage. These proteins are thought to mediate their leukemogenic effects by interfering with the transcriptional programs that regulate differentiation during normal thymocyte development. The recent X−linked SCID gene therapy trial has highlighted a role for LMO2 overexpression as an early event in T−lineage leukemogenesis, as retroviral integration into the LMO2 locus was detected in multiple patients that went on to develop T−ALL. However, our understanding of the effects of aberrant LMO2 expression upon human T−lymphopoiesis is currently limited. In order to address this area, lineage−depleted human umbilical cord blood cells were transduced with a lentivirus encoding LMO2 or a control virus, then seeded upon OP9−DL1 stroma. As expected, control cells underwent a normal stage−specific program of T cell development concluding with the emergence of a population of CD4+CD8+CD3hi TCRαβ+ cells. Interestingly, LMO2−expressing cells exhibited a differentiation block at the double negative (DN: CD8−CD4−CD7+) stage of T−cell development. These LMO2−expressing DN cells had a growth advantage compared to control cells (23 population doublings over 75 days for LMO2 vs. 15 p.d. over 60 days for control) but were not immortalized as they stopped expanding after 75 days of co−culture. In the context of T−cell leukemogenesis, these findings suggest that as an initial hit, LMO2 overexpression can induce a blockage in differentiation, resulting in the generation of a proliferative pre−leukemic pool of DN cells. These cells could subsequently accumulate additional mutations leading to the eventual development of an overt leukemia. Given that TAL1 has been shown to accelerate the development of leukemia in LMO2 transgenic mice, and that these two genes are simultaneously overexpressed in a significant percentage of T−ALL cases, this oncogene was an ideal candidate for a second genetic hit. Thus, a retrovirus encoding TAL1 was utilized to infect the LMO2+ DN T−cell population. The expression of TAL1 in these cells significantly increased their proliferative capacity and greatly extended their lifespan, as greater than 60 population doublings occurred over 220 days of culture on stroma. Of note, TAL−1 overexpression appeared to release the LMO2−induced differentiation block at the DN stage, resulting in the emergence of a population of CD4+CD8+CD3− lymphoblasts. Taken together, these findings describe the first experimental model that studies the early stages of human T−cell leukemogenesis by starting with the physiologically relevant population of primitive primary human hematopoietic cells and analyzing the impact of sequential genetic hits upon T−lymphopoiesis. These data indicate that the aberrant expression of LMO2 contributes to leukemogenesis as an early event by generating a pre−leukemic pool of DN cells and that TAL−1 overexpression in this population acts a cooperating event that leads to the emergence of a highly proliferative, immortalized clone. Given that an experimentally induced leukemia model requires the demonstration of in vivo disease, studies assessing the leukemic potential of human cells co−expressing TAL1 and LMO2 are underway in a novel NOD/SCID system that supports human T cell development.

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In Vitro Models of Human T Cell Development: Dishing Out Progenitor T Cells

Current Immunology Reviews ◽

10.2174/157339507779802205 ◽

2007 ◽

Vol 3 (1) ◽

pp. 57-75 ◽

Cited By ~ 2

Author(s):

Ross La Motte-Mohs ◽

Geneve Awong ◽

Juan Carlos Zuniga-Pflucker

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Development ◽

Cell Development ◽

In Vitro Models ◽

Human T Cell

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Early human T cell development: analysis of the human thymus at the time of initial entry of hematopoietic stem cells into the fetal thymic microenvironment.

Journal of Experimental Medicine ◽

10.1084/jem.181.4.1445 ◽

1995 ◽

Vol 181 (4) ◽

pp. 1445-1458 ◽

Cited By ~ 96

Author(s):

B F Haynes ◽

C S Heinly

Keyword(s):

Stem Cells ◽

T Cell ◽

Hematopoietic Stem Cells ◽

T Cell Development ◽

Fold Increase ◽

Cell Receptor ◽

Cell Development ◽

Hematopoietic Stem ◽

Human Thymus ◽

Human T Cell

To determine events that transpire during the earliest stages of human T cell development, we have studied fetal tissues before (7 wk), during (8.2 wk), and after (9.5 wk to birth) colonization of the fetal thymic rudiment with hematopoietic stem cells. Calculation of the approximate volumes of the 7- and 8.2-wk thymuses revealed a 35-fold increase in thymic volumes during this time, with 7-wk thymus height of 160 microM and volume of 0.008 mm3, and 8.2-wk thymus height of 1044 microM and volume of 0.296 mm3. Human thymocytes in the 8.2-wk thymus were CD4+ CD8 alpha+ and cytoplasmic CD3 epsilon+ cCD3 delta+ CD8 beta- and CD3 zetta-. Only 5% of 8-wk thymocytes were T cell receptor (TCR)-beta+, < 0.1% were TCR-gamma+, and none reacted with monoclonal antibodies against TCR-delta. During the first 16 wk of gestation, we observed developmentally regulated expression of CD2 and CD8 beta (appearing at 9.5 wk), CD1a,b, and c molecules (CD1b, then CD1c, then CD1a), TCR molecules (TCR-beta, then TCR-delta), CD45RA and CD45RO isoforms, CD28 (10 wk), CD3 zeta (12-13 wk), and CD6 (12,75 wk). Whereas CD2 was not expressed at the time of initiation of thymic lymphopoiesis, a second CD58 ligand, CD48, was expressed at 8.2 wk, suggesting a role for CD48 early in thymic development. Taken together, these data define sequential phenotypic and morphologic changes that occur in human thymus coincident with thymus colonization by hematopoietic stem cells and provide insight into the molecules that are involved in the earliest stages of human T cell development.

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Tumor Necrosis Factor Promotes Human T-Cell Development in Nonobese Diabetic/Severe Combined Immunodeficient Mice

Stem Cells ◽

10.1634/stemcells.22-6-1085 ◽

2004 ◽

Vol 22 (6) ◽

pp. 1085-1100 ◽

Cited By ~ 17

Author(s):

Sarit Samira ◽

Christophe Ferrand ◽

Amnon Peled ◽

Arnon Nagler ◽

Yosef Tovbin ◽

...

Keyword(s):

T Cell ◽

Tumor Necrosis Factor ◽

Tumor Necrosis ◽

T Cell Development ◽

Cell Development ◽

Immunodeficient Mice ◽

Nonobese Diabetic ◽

Human T Cell ◽

Necrosis Factor

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Disregulated expression of the transcription factor ThPOK during T-cell development leads to high incidence of T-cell lymphomas

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1424104112 ◽

2015 ◽

Vol 112 (25) ◽

pp. 7773-7778 ◽

Cited By ~ 9

Author(s):

Hyung-Ok Lee ◽

Xiao He ◽

Jayati Mookerjee-Basu ◽

Dai Zhongping ◽

Xiang Hua ◽

...

Keyword(s):

Transcription Factor ◽

T Cell ◽

Lymphoblastic Leukemia ◽

T Cell Development ◽

Cell Receptor ◽

Cell Development ◽

Thymocyte Development ◽

Tcr Signaling ◽

Double Positive ◽

Human T Cell

The transcription factor T-helper-inducing POZ/Krueppel-like factor (ThPOK, encoded by the Zbtb7b gene) plays widespread and critical roles in T-cell development, particularly as the master regulator of CD4 commitment. Here we show that mice expressing a constitutive T-cell–specific ThPOK transgene (ThPOKconst mice) develop thymic lymphomas. These tumors resemble human T-cell acute lymphoblastic leukemia (T-ALL), in that they predominantly exhibit activating Notch1 mutations. Lymphomagenesis is prevented if thymocyte development is arrested at the DN3 stage by recombination-activating gene (RAG) deficiency, but restored by introduction of a T-cell receptor (TCR) transgene or by a single injection of anti-αβTCR antibody into ThPOKconst RAG-deficient mice, which promotes development to the CD4+8+ (DP) stage. Hence, TCR signals and/or traversal of the DN (double negative) > DP (double positive) checkpoint are required for ThPOK-mediated lymphomagenesis. These results demonstrate a novel link between ThPOK, TCR signaling, and lymphomagenesis. Finally, we present evidence that ectopic ThPOK expression gives rise to a preleukemic and self-perpetuating DN4 lymphoma precursor population. Our results collectively define a novel role for ThPOK as an oncogene and precisely map the stage in thymopoiesis susceptible to ThPOK-dependent tumor initiation.

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Interleukin-7 is a critical growth factor in early human T-cell development

Blood ◽

10.1182/blood.v88.11.4239.bloodjournal88114239 ◽

1996 ◽

Vol 88 (11) ◽

pp. 4239-4245 ◽

Cited By ~ 104

Author(s):

J Plum ◽

M De Smedt ◽

G Leclercq ◽

B Verhasselt ◽

B Vandekerckhove

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Development ◽

Cell Development ◽

Molecular Defect ◽

Gamma Chain ◽

Alpha Chain ◽

Interleukin 7 ◽

Human T Cell ◽

Early Human

Highly purified human CD34+ fetal liver stem cells differentiate to mature T cells when seeded in vitro into isolated fetal thymic lobes of severe combined immunodeficient (SCID) mice followed by fetal thymus organ culture (FTOC). Here, this chimeric human-mouse FTOC was used to address the role of interleukin-7 (IL-7) and of the alpha chain of the IL-7 receptor (IL-7R alpha) in early human T-cell development. We report that addition of either the monoclonal antibody (MoAb) M25, which neutralizes both human and mouse IL-7, or the MoAb M21, which recognizes and blocks exclusively the human high-affinity alpha-chain of the IL-7R, results in a profound reduction in human thymic cellularity. Analysis of lymphoid subpopulations indicates that a highly reduced number of cells undergo maturation from CD34+ precursor cells toward CD4+CD3-CD1+ progenitor cells and subsequently toward CD4+CD8+ thymocytes. Our results reveal a critical role for IL-7 during early human thymocyte development, and may explain the absence or highly reduced levels of T cells in patients with X-linked SCID. The molecular defect in these patients has been shown to be a mutation in the gamma chain of the IL-2R. Although this gamma chain is not only present in the IL-2R, but also forms an essential part of other cytokine receptors, including IL-4, IL-7, IL-9, IL-13, and IL-15, the T- cell defect in these patients can be explained by the fact that IL-7 is not able to transduce its signal by the molecular defect of the common gamma (gamma c) chain and that IL-7 is indispensable for T-cell development.

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