| 1. |
- Adolfsson, Jörgen, et al.
(författare)
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Identification of Flt3(+) lympho-myeloid stem cells lacking erythro-megakaryocytic potential: A revised road map for adult blood lineage commitment
- 2005
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Ingår i: Cell. - : Elsevier (Cell Press). - 0092-8674 .- 1097-4172. ; 121:2, s. 295-306
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Tidskriftsartikel (refereegranskat)abstract
- All blood cell lineages derive from a common hematopoietic stem cell (HSC). The current model implicates that the first lineage commitment step of adult pluripotent HSCs results in a strict separation into common lymphoid and common myeloid precursors. We present evidence for a population of cells which, although sustaining a high proliferative and combined lympho-myeloid differentiation potential, have lost the ability to adopt erythroid and megakaryocyte lineage fates. Cells in the Lin-Sca-1+c-kit+ HSC compartment coexpressing high levels of the tyrosine kinase receptor Flt3 sustain granulocyte, monocyte, and B and T cell potentials but in contrast to Lin-Sca-1(+)ckit(+)Flt3(-) HSCs fail to produce significant erythroid and megakaryocytic progeny. This distinct lineage restriction site is accompanied by downregulation of genes for regulators of erythroid and megakaryocyte development. In agreement with representing a lymphoid primed progenitor, Lin(-)Sca-l(+)c-kit(+)CD34(+)Flt3(+) cells display upregulated IL-7 receptor gene expression. Based on these observations, we propose a revised road map for adult blood lineage development.
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| 2. |
- Buza-Vidas, Natalija, et al.
(författare)
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Crucial role of FLT3 ligand in immune reconstitution following bone marrow transplantation and high dose chemotherapy.
- 2007
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 110:1, s. 424-432
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Tidskriftsartikel (refereegranskat)abstract
- Almost 5 decades after the first clinical transplantations, delayed immune reconstitution remains a considerable hurdle in bone marrow transplantation, and the mechanisms regulating immune reconstitution after transplantation remain to be established. Whereas adult fms-like tyrosine kinase 3 ligand-deficient (FL-/-) mice have reduced numbers of early Band T-cell progenitors, they sustain close to normal levels of mature B and T cells. Herein, we demonstrate that adult bone marrow cells fail to reconstitute B-cell progenitors and conventional B cells in lethally irradiated FL-/- recipients, which also display delayed kinetics of T-cell reconstitution. Similarly, FL is essential for B-cell regeneration after chemotherapy-induced myeloablation. In contrast, fetal progenitors reconstitute B lymphopoiesis in FL-/- mice, albeit at reduced levels. A critical role of FL in adult B lymphopoiesis is further substantiated by an age-progressive decline in peripheral conventional B cells in FL-/- mice, whereas fetally and early postnatally derived B1 and marginal zone B cells are sustained in a FL-independent manner. Thus, FL plays a crucial role in sustaining conventional B lymphopoiesis in adult mice and, as a consequence, our findings implicate a critical role of FL in promoting immune reconstitution after myeloablation and bone marrow transplantation.
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| 3. |
- Buza-Vidas, Natalija, et al.
(författare)
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FLT3 receptor and ligand are dispensable for maintenance and posttransplantation expansion of mouse hematopoietic stem cells
- 2009
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 113:15, s. 3453-3460
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Tidskriftsartikel (refereegranskat)abstract
- Originally cloned from hematopoietic stem cell (HSC) populations and its ligand being extensively used to promote ex vivo HSC expansion, the FMS-like tyrosine kinase 3 (FLT3; also called FLK2) receptor and its ligand (FL) were expected to emerge as an important physiologic regulator of HSC maintenance and expansion. However, the role of FLT3 receptor and ligand in HSC regulation remains unclear and disputed. Herein, using Fl-deficient mice, we establish for the first time that HSC expansion in fetal liver and after transplantation is FL independent. Because previous findings in Flk2(-/-) mice were compatible with an important role of FLT3 receptor in HSC regulation and because alternative ligands might potentially interact directly or indirectly with FLT3 receptor, we here also characterized HSCs in Flk2(-/-) mice. Advanced phenotypic as well as functional evaluation of Flk2(-/-) HSCs showed that the FLT3 receptor is dispensable for HSC steady-state maintenance and expansion after transplantation. Taken together, these studies show that the FLT3 receptor and ligand are not critical regulators of mouse HSCs, neither in steady state nor during fetal or posttransplantation expansion. (Blood. 2009; 113: 3453-3460)
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| 4. |
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| 5. |
- Cheng, Min, et al.
(författare)
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Distinct and overlapping patterns of cytokine regulation of thymic and bone marrow-derived NK cell development.
- 2009
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Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:3, s. 1460-1468
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Tidskriftsartikel (refereegranskat)abstract
- Although bone marrow (BM) represents the main site for postnatal NK cell development, recently a distinct thymic-dependent NK cell pathway was identified. These studies were designed to investigate the role of cytokines in regulation of thymic NK cells and to compare with established regulatory pathways of BM-dependent NK cell compartment. The common cytokine receptor gamma-chain (Il2rg) essential for IL-15-induced signaling, and FMS-like tyrosine kinase 3 (FLT3) receptor ligand (Flt3l) were previously identified as important regulatory pathways of the BM NK cell compartment based on lack of function studies in mice, however their complementary action remains unknown. By investigating mice double-deficient in Il2rg and Flt3l (Flt3l(-/-) Il2rg(-/-)), we demonstrate that FLT3L is important for IL2Rg-independent maintenance of both immature BM as well as peripheral NK cells. In contrast to IL-7, which is dispensable for BM but important for thymic NK cells, IL-15 has a direct and important role in both thymic and BM NK cell compartments. Although thymic NK cells were not affected in Flt3l(-/-) mice, Flt3l(-/-)Il2rg(-/-) mice lacked detectable thymic NK cells, suggesting that FLT3L is also important for IL-2Rg-independent maintenance of thymic NK cells. Thus, IL-2Rg cytokines and FLT3L play complementary roles and are indispensable for homeostasis of both BM and thymic dependent NK cell development, suggesting that the cytokine pathways crucial for these two distinct NK cell pathways are largely overlapping.
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| 6. |
- Jensen, Christina, et al.
(författare)
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FLT3 ligand and not TSLP is the key regulator of IL-7-independent B-1 and B-2 B Lymphopoiesis.
- 2008
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 112, s. 2297-2304
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypically and functionally distinct progenitors and developmental pathways have been proposed to exist for fetally-derived B-1 and conventional B-2 cells. Although IL-7 appears to be the primary regulator of fetal and adult B lymphopoiesis in mice, considerable fetal B lymphopoiesis and postnatal B-cells are sustained in the absence of IL-7, and in man B-cell generation is suggested to be largely or entirely IL-7-independent, as severe combined immune-deficient patients with IL-7-deficiency appear to have normal B-cell numbers. However, the role of other cytokines in IL-7-independent B lymphopoiesis remains to be established. Although thymic stromal lymphopoietin (TSLP) has been proposed to be the main factor driving IL-7-independent B lymphopoiesis, and to distinguish fetal from adult B-cell progenitor development in mice, recent studies failed to support a primary role of TSLP in IL-7-independent fetal B-cell development. However, the role of TSLP in IL-7-independent adult B lymphopoiesis and in particular in regulation of B-1 cells remains to be established. Herein, we demonstrate that rather than TSLP, IL-7 and FLT3 ligand (FLT3L) are combined responsible for all B-cell generation in mice, including recently identified B-1-specified cell progenitors. Thus, the same IL-7 and FLT3L-mediated signaling regulate alternative cellular pathways of fetal and adult B-1 and B-2 B lymphopoiesis.
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| 7. |
- Jensen, Christina, et al.
(författare)
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Permissive roles of hematopoietin and cytokine tyrosine kinase receptors in early T-cell development
- 2008
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 111:4, s. 2083-2090
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Tidskriftsartikel (refereegranskat)abstract
- Although several cytokines have been demonstrated to be critical regulators of development of multiple blood cell lineages, it remains disputed to what degree they act through instructive or permissive mechanisms. Signaling through the FMS-like tyrosine kinase 3 (FLT3) receptor and the hematopoietin IL-7 receptor alpha (IL-7Ralpha) has been demonstrated to be of critical importance for sustained thymopoiesis. Signaling triggered by IL-7 and thymic stromal lymphopoietin (TSLP) is dependent on IL-7Ralpha, and both ligands have been implicated in T-cell development. However, we demonstrate that, whereas thymopoiesis is abolished in adult mice doubly deficient in IL-7 and FLT3 ligand (FLT3L), TSLP does not play a key role in IL-7-independent or FLT3L-independent T lymphopoiesis. Furthermore, whereas previous studies implicated that the role of other cytokine tyrosine kinase receptors in T lymphopoiesis might not involve permissive actions, we demonstrate that ectopic expression of BCL2 is sufficient not only to partially correct the T-cell phenotype of Flt3l(-/-) mice but also to rescue the virtually complete loss of all discernable stages of early T lymphopoiesis in Flt3l(-/-)Il7r(-/-) mice. These findings implicate a permissive role of cytokine receptors of the hematopoietin and tyrosine kinase families in early T lymphopoiesis.
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| 8. |
- Sitnicka Quinn, Ewa, et al.
(författare)
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Critical role of FLT3 ligand in IL-7 receptor-independent T lymphopoiesis and regulation of lymphoid-primed multipotent progenitors
- 2007
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Ingår i: Blood. - Washington, DC : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 110:8, s. 2955-2964
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Tidskriftsartikel (refereegranskat)abstract
- The molecular pathways regulating lymphoid priming, fate, and development of multipotent bone marrow (BM) stem/progenitor cells that continuously replace thymic progenitors remain largely unknown. Herein, we show that fms-like tyrosine kinase 3 (Flt3) ligand (Fl)-deficient mice have distinct reductions in the earliest thymic progenitors in fetal, postnatal, and adult thymus. A critical role of FL in thymopoiesis was particularly evident in the absence of interleukin-7 receptor alpha (IL-7Ralpha) signaling. Fl-/-Il-7r-/- mice have extensive reductions in fetal and postnatal thymic progenitors that result in a loss of active thymopoiesis in adult mice, demonstrating an indispensable role of FL in IL-7Ralpha-independent fetal and adult T lymphopoiesis. Moreover, we establish a unique and critical role of FL, distinct from that of IL-7Ralpha, in regulation of the earliest lineage-negative (Lin(-)) Lin(-)SCA1+KIT+ (LSK) FLT3(hi) lymphoid-primed multipotent progenitors in BM, demonstrating a key role of FLT3 signaling in regulating the very earliest stages of lymphoid progenitors.
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| 9. |
- Sitnicka Quinn, Ewa
(författare)
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From the bone marrow to the thymus: the road map of early stages of T-cell development.
- 2009
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Ingår i: Critical Reviews in Immunology. - 1040-8401. ; 29:6, s. 487-530
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Forskningsöversikt (refereegranskat)abstract
- The thymus produces new T cells throughout life but has no self-renewing ability and requires replenishment and recruitment of progenitors derived from the bone marrow. Despite the progress in delineation of mature blood cell development several questions remain regarding T lymphopoiesis. Understanding the developmental stages from multipotent hematopoietic stem cells (HSCs) to the T-cell lineage-restricted progenitors has many potential clinical implications as it is important for understanding malignant transformation in T-cell cancer, accelerating T-cell regeneration after bone marrow transplantation and chemotherapy, and establishing new therapies to treat T-cell immune deficiencies. This review focuses on the steps leading from the HSCs in the bone marrow to the lineage committed T cells inside the thymus.
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| 10. |
- Svensson Frej, Marcus, et al.
(författare)
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Involvement of CCR9 at multiple stages of adult T lymphopoiesis.
- 2008
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 83:1, s. 156-164
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Tidskriftsartikel (refereegranskat)abstract
- The chemokine CCL25 is constitutively expressed in the thymus, and its receptor CCR9 is expressed on subsets of developing thymocytes. Nevertheless, the function of CCL25/CCR9 in adult thymopoiesis remains unclear. Here, we demonstrate that purified CCR9–/– hematopoietic stem cells are deficient in their ability to generate all major thymocyte subsets including double-negative 1 (DN1) cells in competitive transfers. CCR9–/– bone marrow contained normal numbers of lineage– Sca-1+c-kit+, common lymphoid progenitors, and lymphoid-primed multipotent progenitors (LMPP), and CCR9–/– LMPP showed similar T cell potential as their wild-type (WT) counterparts when cultured on OP9–{delta}-like 1 stromal cells. In contrast, early thymic progenitor and DN2 thymocyte numbers were reduced in the thymus of adult CCR9–/– mice. In fetal thymic organ cultures (FTOC), CCR9–/– DN1 cells were as efficient as WT DN1 cells in generating double-positive (DP) thymocytes; however, under competitive FTOC, CCR9–/– DP cell numbers were reduced significantly. Similarly, following intrathymic injection into sublethally irradiated recipients, CCR9–/– DN cells were out-competed by WT DN cells in generating DP thymocytes. Finally, in competitive reaggregation thymic organ cultures, CCR9–/– preselection DP thymocytes were disadvantaged significantly in their ability to generate CD4 single-positive (SP) thymocytes, a finding that correlated with a reduced ability to form TCR-MHC-dependent conjugates with thymic epithelial cells. Together, these results highlight a role for CCR9 at several stages of adult thymopoiesis: in hematopoietic progenitor seeding of the thymus, in the DN-DP thymocyte transition, and in the generation of CD4 SP thymocytes.
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| 11. |
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