In Vitro Exposure to DL-4 Increases the in Vitro and In Vivo T-Lymphopoietic Potential of CB Derived CD34+ Progenitor Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2980-2980
Author(s):  
Christian Reimann ◽  
Liliane Liliane Dal-Cortivo ◽  
Emmanuelle M. Six ◽  
Andrea Schiavo ◽  
Marina Cavazzana-Calvo ◽  
...  
Keyword(s):  
T Cell ◽  
Developmental Stages ◽  
T Cell Development ◽  
Cell Development ◽  
T Cell Reconstitution ◽  
Cd34 Cells ◽  
Peripheral T Cells ◽  
Lymphoid Progenitors

Abstract Abstract 2980 Notchligand-based culture systems such as OP9-DL1 cells induce HSC to engage towards the T-cell developmental program and allow generation of T-lymphoid progenitors in vitro. In vitro generated murine T-lymphoid progenitors accelerated T-cell reconstitution in vivo. In consistency, human T-lymphoid progenitors generated in co-culture with OP9-DL1 cells enhanced thymic repopulation when injected into NOD/SCID/gc−/− mice (NSG). However, positive effects of human T-lymphoid progenitors on peripheral T-cell reconstitution have not been reported yet. Besides, Notchligand-based culture systems, consisting of genetically modified murine cells might raise safety concern for clinical use. It has been described that exposure of CD34+ cells to immobilized DL4 induces the T-cell developmental program even in absence of stromal cell support. Recently, we have made use of this system to generate T-lymphoid progenitors in vitro. In the present study we have further characterized their T-lymphoid potential in vitro and in vivo. Exposure of human CB-derived CD34+ cells to immobilized DL4 allowed generation of CD34+CD7+ and CD34−CD7++CD5+ progenitors displaying a similar phenotype as early thymic progenitors (ETP) and the prethymocytes (pre-T). Within the DL-4 derived ETP- and preT-like progenitors we observed subsequent up regulation of genes involved in T-cell development and silencing of genes implied in B-cell and myeloid differentiation. T-cell commitment of DL-4 progenitors could be further confirmed by early and intermediate rearrangement events within the TCR d/g/b genes. The pattern of gene expression profile and TCR-rearrangement events displayed a pattern similar to what we observed in corresponding intrathymic developmental stages. DL4-progenitors obtained after 7 days of culture displayed a 30-fold increased in vitro T-lymphoid potential as compared to untreated CD34+ CB progenitors. DL4 ETP-like and preT-like progenitors further completed T-cell differentiation in vitro (in OP9DL1 co-culture) faster than native CD34+ CB progenitors. When transferred into NSG, DL4 progenitors obtained after 7 days of culture were able to repopulate the recipients' thymus and to give rise to mature, polyclonal intrathymic and peripheral T-cells. Two months after transfer recipients of DL4 progenitors displayed advanced intrathymic T-cell development as compared to recipients of CD34+ CB cells. Furthermore, peripheral T-cells could be observed in a number of DL-4 progenitor recipients but not in control mice. Our experiments provide further evidence that DL4 allows in vitro induction of T-cell development and generation of early T-lymphoid progenitors in a system devoid of stromal cell support. These progenitors feature phenotypical and molecular characteristics of immature thymic developmental stages. Moreover, they are able to accelerate T-cell development in vitro and when transferred into NSG. This work provides further evidence of the ability of in vitro -generated human T-cell progenitors to accelerate T-cell reconstitution and simultaneously introduces a culture technique that could be rapidly transferred into a clinical setting. Disclosures: No relevant conflicts of interest to declare.

Further Characterization of T-Cellular Precursors Generated From CD34+ Progenitors by Exposure to Immobilized Notch Ligand Delta-Like 4 In Vitro.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3712-3712
Author(s):  
Christian Reimann ◽  
Andrea Schiavo ◽  
Julien Rouiller ◽  
Elodie Vidal ◽  
Kheira Beldjord ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
T Stage ◽  
T Cell Reconstitution ◽  
Peripheral T Cells ◽  
Precursor Frequency ◽  
Novel Strategy

Abstract Abstract 3712 Injection of donor derived T-cellular precursors has been proposed as a novel strategy to shorten delayed reconstitution of the T-lymphoid compartment following HSCT. In the past years, several research groups have successfully generated murine and human T-cellular precursors in vitro using Notchligand-based coculture systems such as OP9-DL1 or Tst-DL4. Murine T-cellular precursors generated in vitro, promoted reconstitution of the T-cellular compartment when applied in murine HSCT-models. In consistency, transfer of human T-cellular precursors, generated in vitro in coculture with OP9-DL1 or Tst-DL4 resulted in enhanced thymic repopulation in NOD/SCID/gc−/− mice. Yet, positive effects on peripheral T-cell reconstitution have not been reported. Moreover, clinical application of OP9-DL1 or Tst-DL4 coculture systems is limited, since they consist of murine stromal cells transduced with either DL1 or DL4. It has been described that exposure of CD34+ cells to immobilized DL4 induces T-cell differentiation in vitro and allows expansion human T-cellular precursors even in absence of stromal cell support. However, the hypothesis that DL4 alone can drive hematopoietic progenitors towards a T-cell fate in vitro, requires more evidence. Here, we further characterized the in vitro and in vivo potential of T-cellular precursors generated by single exposure to DL4. We exposed human CD34+ progenitors to immobilized DL4 in the presence of different cytokine combinations implicated in human haematopoiesis. Within 7 days, CD34+CD7+ and CD34−CD7++ T-cellular precursors emerged in the presence of DL4, but not under control conditions. After 7 days the CD34+CD7+ population subsequently declined while the CD34−CD7++ population further expanded. Two distinct progenitor subsets, CD5+ and CD5-, emerged within the CD34−CD7++ population. The CD34−CD7++CD5+ subset partially acquired CD1a, corresponding to a developmental stage between the early thymic progenitor (ETP) and the prethymocyte (pre-T) stage. Conversely to what observed in the OP9-DL1 system, T-cell development did not progress beyond the pre-T-stage. Indeed, we neither observed more advanced stages of T-cell development, such as immature single positive CD4+ cells, nor complete TCR-rearrangements. 7-day exposure to immobilized DL4 induced a 90-fold increase of T-precursor frequency in CD34+ progenitors (1/8800 before culture vs. 1/90 after culture) as confirmed by limiting dilution assays on OP9-DL1. All T-cellular precursor activity was restricted to cells expressing CD34, CD7 or both (frequency: 1/9). In particular, elevated T-cellular precursor levels were found in the subsets expressing CD7 (CD34+/CD7+ and CD34−/CD7+), while the T-cellular precursor frequency in the CD34+/CD7− subset was equal to that seen in non-cultured CD34+ progenitors. In consistency the CD34−CD7− population did not contain any detectable T-cellular precursors. After 7 day exposure to DL4, cells phenotypically corresponding to T-cellular precursors were transferred into NOD/SCID/gc−/− mice. Within 2 months following HSCT, cells exposed to DL4 were able to reconstitute the recipients' thymus and partially gave rise to peripheral T-cells. When injecting non-cultured CD34+ progenitors, thymic reconstitution was likewise seen 2 months after HSCT. However, intrathymic T-cell development was less advanced and peripheral T-cells were absent. In contrast, cells cultured in presence of a control peptide did not retain any potential to repopulate the recipients' thymus. Our experiments provide further evidence that exposure DL4 induces early human T-cell development and allows generation of large numbers of T-cellular precursors in vitro. These precursors feature phenotypical and molecular properties corresponding to early precursors found in the human thymus. Furthermore, they have an increased potential to further differentiate into mature T-cells in vitro and when transferred into immunodeficient mice. Our preliminary data suggest, that injection of T-cellular precursors accelerates T-cell reconstitution after HSCT and provides further evidence for the feasibility of this novel strategy of immunotherapy. Disclosures: No relevant conflicts of interest to declare.

The in Vitro and In Vivo Oncogenic Activity of Homodimeric Mutant of Interleukin-7 Receptor a Chain (IL7Rα) Highlights the Significance of the IL7Rα/Jak1 Pathway in T-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 73-73
Author(s):  
Kazuaki Yokoyama ◽  
Nozomi Yokoyama ◽  
Kiyoko Izawa ◽  
Ai Kotani ◽  
Ratanakanit Harnprasopwat ◽  
...  
Keyword(s):  
T Cell ◽  
Lymphoblastic Leukemia ◽  
T Cell Development ◽  
Cell Development ◽  
Gamma Delta ◽  
Interleukin 7 ◽  
Signaling Axis ◽  
A Chain

Abstract Abstract 73 Interleukin-7 (IL7) is essential for T cell development and homeostasis. Dysregulation of signals that control normal T-cell development has been implicated in the onset of T-cell acute lymphoblastic leukemia (T-ALL). By analogy to activating mutations in the Notch pathways, we hypothesized that any mutations in the IL7 signaling axis might also contribute to T-ALL. Direct sequencing of human IL7 receptor a chain (hIL7RA) gene in a panel of 16 T-ALL cell lines identified two types of mutations in two different cell lines. One was an insertion mutation of 4 amino acids (LSRC) in the transmembrane region (INS, Fig.1A) from DND-41, a gamma-delta TCR+ T-ALL cell line, and the other was a truncated, loss-of-function, mutation in the cytoplasmic region from MOLT-4. We demonstrated that hIL7RA-INS mutant spontaneously formed a homodimer and constitutively activated downstream signals including Stat family members (1, 3 and 5), Akt and Erk via Jak1, but not Jak3. Next, we investigated oncogenic activity of hIL7RA-INS in primary hematopoietic progenitor cells. To this aim, lin− E.14 Balb/c fetal liver (FL) cells were retrovirally transduced with hIL7RA-INS in parallel with hIL7RA-wild type (WT), and then tested for their cytokine dependence in vitro. As expected, only hIL7RA-INS-transduced lin−FL cells showed abrogation of cytokine dependence. hIL7RA-transduced lin−FL cells were also transplanted into lethally irradiated syngeneic mice. Within 7–9 weeks after transplantation of lin−FL cells transduced with hIL7RA-INS, but not with hIL7RA-WT, recipient mice developed well-tolerated myelo- and lymphoproliferative disorders, characterized by marked leukocytosis, systemic lymphadenopathy and splenomegaly (Fig.1B). Notably, concomitant increase in hIL7RA+gamma-delta TCR+ T cells and decrease in B cells were observed in peripheral blood (Fig.1C). Histological examination of bone marrow, spleen and liver specimens from diseased mice revealed moderate to severe myeloid hyperplasia, disrupted splenic architecture by disseminated mature myeloid cells and infiltration of both myeloid and mononuclear cells into hepatic parenchyma, respectively. In addition, recipient mice for hIL7RA-INS-transduced lin−FL cells frequently manifested ruffled fur as well as mononuclear cell infiltration into salivary gland and pericardium, suggesting an autoimmune-like disorder. However, during median follow-up of 11 weeks, these recipient mice did not develop either overt leukemia or lymphoma, indicating that additional transforming events are required for evolution to aggressive hematological malignancies. These in vivo findings highlighted the possibility that aberrant signals via IL7RA in hematopoietic stem/progenitor cells might preferentially stimulate myelopoiesis over lymphopoiesis, and also confirmed the essential role of IL7RA in gamma-delta TCR+ T cell development, previously shown by IL7RA-knockout mice. Taken together, we speculated that dysregulated IL7RA signaling axis might be involved in the onset of T-ALL, especially with gamma-delta TCR+ phenotype. Finally, the present study, together with the recent report (JEM 208:901, 2011), emphasizes the significance of the sequential Notch-IL7RA pathways in the pathogenesis of T-ALL as well as the dominant role of the IL7RA/Jak1 axis in IL7 proliferative signal. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Essential Role of Survivin, an Inhibitor of Apoptosis Protein, in T Cell Development, Maturation, and Homeostasis

2003 ◽  
Vol 199 (1) ◽  
pp. 69-80 ◽  
Author(s):  
Zheng Xing ◽  
Edward M. Conway ◽  
Chulho Kang ◽  
Astar Winoto
Keyword(s):  
T Cells ◽  
T Cell ◽  
Developmental Stages ◽  
T Cell Development ◽  
Cell Development ◽  
Inhibitor Of Apoptosis ◽  
Proliferating Cells ◽  
Inhibitor Of Apoptosis Protein ◽  
Apoptosis Protein

Survivin is an inhibitor of apoptosis protein that also functions during mitosis. It is expressed in all common tumors and tissues with proliferating cells, including thymus. To examine its role in apoptosis and proliferation, we generated two T cell–specific survivin-deficient mouse lines with deletion occurring at different developmental stages. Analysis of early deleting survivin mice showed arrest at the pre–T cell receptor proliferating checkpoint. Loss of survivin at a later stage resulted in normal thymic development, but peripheral T cells were immature and significantly reduced in number. In contrast to in vitro studies, loss of survivin does not lead to increased apoptosis. However, newborn thymocyte homeostatic and mitogen-induced proliferation of survivin-deficient T cells were greatly impaired. These data suggest that survivin is not essential for T cell apoptosis but is crucial for T cell maturation and proliferation, and survivin-mediated homeostatic expansion is an important physiological process of T cell development.

T-cell developmental blockage by tachykinin antagonists and the role of hemokinin 1 in T lymphopoiesis

Blood ◽  
2003 ◽  
Vol 102 (6) ◽  
pp. 2165-2172 ◽  
Author(s):  
Yu Zhang ◽  
Christopher J. Paige
Keyword(s):  
T Cell ◽  
B Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Double Positive ◽  
Peptide Family ◽  
Tachykinin Antagonists ◽  
B Cell Precursors

Abstract Hemokinin 1 (HK-1) is a new member of the tachykinin peptide family that is expressed in hematopoietic cells. Recent reports studying mouse, rat, and human orthologs of HK-1 demonstrate a broader distribution than originally reported. Our previous studies demonstrated that HK-1, by promoting proliferation, survival, and possibly maturation of B-cell precursors, plays an important role in B lymphopoiesis. Here we present data showing that HK-1 also influences T-cell development at a similar stage of differentiation. This peptide enhanced the proliferation of T-cell precursors and increased the number of thymocytes in fetal thymus organ cultures (FTOCs). Tachykinin antagonists, on the other hand, greatly reduced the cellularity of thymi both in vivo and in vitro. The major reduction occurred in the CD4/CD8 double-positive (DP) cells and the CD44–CD25+ subset of the CD4/CD8 double-negative (DN) cells. Of note, these populations also express HK-1, raising the possibility of autocrine or paracrine pathways influencing T-cell development as we previously reported for B-cell development. Consistent with this, the detrimental effect of tachykinin antagonists could be partially overcome with exogenous HK-1 peptide.

scholarly journals Hierarchy of Notch–Delta interactions promoting T cell lineage commitment and maturation

2007 ◽  
Vol 204 (2) ◽  
pp. 331-343 ◽  
Author(s):  
Valerie Besseyrias ◽  
Emma Fiorini ◽  
Lothar J. Strobl ◽  
Ursula Zimber-Strobl ◽  
Alexis Dumortier ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Cell Lineage ◽  
Cell Development ◽  
Lineage Commitment ◽  
Binding Studies ◽  
Maturation In Vitro ◽  
Cell Commitment

Notch1 (N1) receptor signaling is essential and sufficient for T cell development, and recently developed in vitro culture systems point to members of the Delta family as being the physiological N1 ligands. We explored the ability of Delta1 (DL1) and DL4 to induce T cell lineage commitment and/or maturation in vitro and in vivo from bone marrow (BM) precursors conditionally gene targeted for N1 and/or N2. In vitro DL1 can trigger T cell lineage commitment via either N1 or N2. N1- or N2-mediated T cell lineage commitment can also occur in the spleen after short-term BM transplantation. However, N2–DL1–mediated signaling does not allow further T cell maturation beyond the CD25+ stage due to a lack of T cell receptor β expression. In contrast to DL1, DL4 induces and supports T cell commitment and maturation in vitro and in vivo exclusively via specific interaction with N1. Moreover, comparative binding studies show preferential interaction of DL4 with N1, whereas binding of DL1 to N1 is weak. Interestingly, preferential N1–DL4 binding reflects reduced dependence of this interaction on Lunatic fringe, a glycosyl transferase that generally enhances the avidity of Notch receptors for Delta ligands. Collectively, our results establish a hierarchy of Notch–Delta interactions in which N1–DL4 exhibits the greatest capacity to induce and support T cell development.

scholarly journals Normal T-Cell Development and Immune Functions in TRIM-Deficient Mice

2006 ◽  
Vol 26 (9) ◽  
pp. 3639-3648 ◽  
Author(s):  
Uwe Kölsch ◽  
Börge Arndt ◽  
Dirk Reinhold ◽  
Jonathan A. Lindquist ◽  
Nicole Jüling ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
T Cell Subsets ◽  
Immune Functions ◽  
Deficient Mice

ABSTRACT The transmembrane adaptor molecule TRIM is strongly expressed within thymus and in peripheral CD4+ T cells. Previous studies suggested that TRIM is an integral component of the T-cell receptor (TCR)/CD3 complex and might be involved in regulating TCR cycling. To elucidate the in vivo function of TRIM, we generated TRIM-deficient mice by homologous recombination. TRIM−/− mice develop normally and are healthy and fertile. However, the animals show a mild reduction in body weight that appears to be due to a decrease in the size and/or cellularity of many organs. The morphology and anatomy of nonlymphoid as well as primary and secondary lymphoid organs is normal. The frequency of thymocyte and peripheral T-cell subsets does not differ from control littermates. In addition, a detailed analysis of lymphocyte development revealed that TRIM is not required for either positive or negative selection. Although TRIM−/− CD4+ T cells showed an augmented phosphorylation of the serine/threonine kinase Akt, the in vitro characterization of peripheral T cells indicated that proliferation, survival, activation-induced cell death, migration, adhesion, TCR internalization and recycling, TCR-mediated calcium fluxes, tyrosine phosphorylation, and mitogen-activated protein family kinase activation are not affected in the absence of TRIM. Similarly, the in vivo immune response to T-dependent and T-independent antigens as well as the clinical course of experimental autoimmune encephalomyelitis, a complex Th1-mediated autoimmune model, is comparable to that of wild-type animals. Collectively, these results demonstrate that TRIM is dispensable for T-cell development and peripheral immune functions. The lack of an evident phenotype could indicate that TRIM shares redundant functions with other transmembrane adaptors involved in regulating the immune response.

scholarly journals Artificial thymic organoids represent a reliable tool to study T-cell differentiation in patients with severe T-cell lymphopenia

2020 ◽  
Vol 4 (12) ◽  
pp. 2611-2616 ◽  
Author(s):  
Marita Bosticardo ◽  
Francesca Pala ◽  
Enrica Calzoni ◽  
Ottavia M. Delmonte ◽  
Kerry Dobbs ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
T Cell Differentiation ◽  
Cd8 Cells ◽  
Cd34 Cells ◽  
T Cell Lymphopenia ◽  
Stromal Cell Line

Abstract The study of early T-cell development in humans is challenging because of limited availability of thymic samples and the limitations of in vitro T-cell differentiation assays. We used an artificial thymic organoid (ATO) platform generated by aggregating a DLL4-expressing stromal cell line (MS5-hDLL4) with CD34+ cells isolated from bone marrow or mobilized peripheral blood to study T-cell development from CD34+ cells of patients carrying hematopoietic intrinsic or thymic defects that cause T-cell lymphopenia. We found that AK2 deficiency is associated with decreased cell viability and an early block in T-cell development. We observed a similar defect in a patient carrying a null IL2RG mutation. In contrast, CD34+ cells from a patient carrying a missense IL2RG mutation reached full T-cell maturation, although cell numbers were significantly lower than in controls. CD34+ cells from patients carrying RAG mutations were able to differentiate to CD4+CD8+ cells, but not to CD3+TCRαβ+ cells. Finally, normal T-cell differentiation was observed in a patient with complete DiGeorge syndrome, consistent with the extra-hematopoietic nature of the defect. The ATO system may help determine whether T-cell deficiency reflects hematopoietic or thymic intrinsic abnormalities and define the exact stage at which T-cell differentiation is blocked.

In Vitro Generation of Human T-Cell Precursors From Bone Marrow CD34+ Cells by Short Exposure to Immobilized Notch-Ligand Delta-Like 4.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3532-3532
Author(s):  
Christian Reimann ◽  
Liliane Dal-Cortivo ◽  
Brigitte Ternaux ◽  
Emmanuelle Six ◽  
Julien Rouiller ◽  
...  
Keyword(s):  
T Cell ◽  
Nk Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Short Exposure ◽  
Cell Phenotype ◽  
Notch Ligand ◽  
Human T Cell ◽  
Cd34 Cells

Abstract Abstract 3532 Poster Board III-469 Prolonged posttransplant immune deficiency is a major complication following hematopoietic stem cell transplantation, particularly in the T-lymphoid compartment. Accelerating T-cell development by injecting donor derived T-cell precursors has been proposed as a novel strategy to shorten the immune deficient phase. Several research groups have successfully generated T-cell precursors from murine and human HSC in vitro by transitory exposure to the Notch-ligand presenting murine OP9DL1-cell line. Transfer of the in vitro generated murine T-cell precursors into irradiated NOD/SCID/γcnull-mice accelerated T-cellular reconstitution. However, the clinical application of the OP9DL1-system is limited. Recent studies have demonstrated that short exposure of cord blood CD34+ cells to Notch-ligand Delta-like 4 is sufficient to promote human T-cell differentiation in vitro. Here, we modified this technique to better characterize and ameliorate T-cell development in vitro, with the objective of eventually transferring this method to a clinical phase. Towards this aim, we exposed human CD34+ HSC derived from any available source to immobilized Notch-ligand Delta-like 4 in the presence of different cytokine combinations implicated in human haematopoiesis (IL-7, SCF, Flt3-ligand and TPO). Within 7 days a population of CD34+CD7+ and CD34-CD7++ T-cell precursors emerged in the presence of Delta-like 4, but not under control conditions. After 7 days the CD34+CD7+ population subsequently declined while further amplification of the CD34-CD7++ population was observed. Two distinct progenitor subsets emerged within the CD34-CD7++ population, namely CD34-CD7++CD5+ and CD34-CD7++CD5-. The CD34-CD7++CD5+ subset further acquired CD1a and, thus, adopted a pre-T-cell phenotype. Between days 7 and 14 the CD34-CD7++CD5- acquired a NK-cell phenotype, as indicated by CD16 and CD56 expression. Beyond 14 days no further expansion of the pre-T-cell fraction was observed, while the NK-cell fraction continued proliferating. More advanced stages T-cell development, such as immature single positive CD4+ cells as observable in OP9DL1 co-cultures, did not arise after exposing cells only to immobilized Delta-like4. Intermittent emergence of a CD13+CD14+CD7- myeloid population was observed within the first 14 days of culture on Delta-like 4; however, this population disappeared spontaneously and did not preserve its common myeloid progenitor. Selecting a more immature CD34+CD38- population resulted in a two-fold increase of the frequency of CD34+CD7+ and CD34-CD7++ cells as compared to the whole CD34+ population, while myeloid differentiation was inhibited. A further increase was obtained by replanting cultured cells to freshly coated plates with Delta-like 4 every 3 days of culture. T-cell precursors cells derived after 7 days of culture were injected into NOD/SCID/γcnull mice. The in vivo-experiments are ongoing and results are pending. Our results provide further evidence that human T-cell precursors can be generated in vitro, not only in co-culture with murine OP9DL1-cells but also by short exposure to immobilized Notch-ligand Delta-like 4. These ongoing experiments are an important prerequisite for the potential clinical application of this method. Disclosures: No relevant conflicts of interest to declare.

Strategies of immune reconstitution: Effects of lymphokines on murine T cell development in vitro and in vivo

Life Sciences ◽  
1989 ◽  
Vol 44 (13) ◽  
pp. v-xii ◽  
Author(s):  
J.W. Hadden ◽  
H. Chen ◽  
Y. Wang ◽  
A. Galy ◽  
E. Hadden
Keyword(s):  
T Cell ◽  
Immune Reconstitution ◽  
T Cell Development ◽  
Cell Development ◽  
Development In Vitro

scholarly journals Delta-like 4 is indispensable in thymic environment specific for T cell development

2008 ◽  
Vol 205 (11) ◽  
pp. 2507-2513 ◽  
Author(s):  
Katsuto Hozumi ◽  
Carolina Mailhos ◽  
Naoko Negishi ◽  
Ken-ichi Hirano ◽  
Takashi Yahata ◽  
...  
Keyword(s):  
T Cell ◽  
Notch Signaling ◽  
Cell Fate ◽  
T Cell Development ◽  
Cell Development ◽  
Thymic Epithelial Cells ◽  
Hematopoietic Progenitors ◽  
Double Positive

The thymic microenvironment is required for T cell development in vivo. However, in vitro studies have shown that when hematopoietic progenitors acquire Notch signaling via Delta-like (Dll)1 or Dll4, they differentiate into the T cell lineage in the absence of a thymic microenvironment. It is not clear, however, whether the thymus supports T cell development specifically by providing Notch signaling. To address this issue, we generated mice with a loxP-flanked allele of Dll4 and induced gene deletion specifically in thymic epithelial cells (TECs). In the thymus of mutant mice, the expression of Dll4 was abrogated on the epithelium, and the proportion of hematopoietic cells bearing the intracellular fragment of Notch1 (ICN1) was markedly decreased. Corresponding to this, CD4 CD8 double-positive or single-positive T cells were not detected in the thymus. Further analysis showed that the double-negative cell fraction was lacking T cell progenitors. The enforced expression of ICN1 in hematopoietic progenitors restored thymic T cell differentiation, even when the TECs were deficient in Dll4. These results indicate that the thymus-specific environment for determining T cell fate indispensably requires Dll4 expression to induce Notch signaling in the thymic immigrant cells.

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