Showing papers on "Haematopoiesis published in 1990"
TL;DR: The results indicate that osteoclasts are also derived from the mature monocytes and macrophages when a suitable microenvironment is provided by bone marrow-derived stromal cells.
Abstract: We previously reported that osteoclast-like cells were formed in cocultures of a mouse marrow-derived stromal cell line (ST2) with mouse spleen cells in the presence of 1 alpha, 25-dihydroxyvitamin D3 and dexamethasone. In this study, we developed a new coculture system to determine the origin of osteoclasts. When relatively small numbers of mononuclear cells (10(3)-10(5) cells per well) obtained from mouse bone marrow, spleen, thymus, or peripheral blood were cultured for 12 days on the ST2 cell layers, they formed colonies with a linear relationship between the number of colonies formed and the number of hemopoietic cells inoculated. Tartrate-resistant acid phosphatase (TRAPase)-positive mononuclear and multinucleated cells appeared in the colonies (TRAPase-positive colonies) in response to 1 alpha, 25-dihydroxyvitamin D3 and dexamethasone. When hemopoietic cells suspended in a collagen-gel solution were cultured on the ST2 cell layers to prevent their movement, TRAPase-positive colonies were similarly formed, indicating that each colony originated from a single cell. All of the colonies consisted of nonspecific esterase-positive cells. The monocyte-depleted population prepared from peripheral blood failed to form colonies, whereas the monocyte-enriched population produced a large number of TRAPase-positive colonies. In addition, alveolar macrophages formed TRAPase-positive colonies most efficiently on the ST2 cell layers in the presence of the two hormones. Salmon 125I-labeled calcitonin specifically bound to the TRAPase-positive cells. Resorption lacunae were formed on dentine slices on which cocultures were performed. When direct contact between the peripheral blood cells and the ST2 cells was inhibited by a collagen-gel sheet, no TRAPase-positive cells were formed. These results indicate that osteoclasts are also derived from the mature monocytes and macrophages when a suitable microenvironment is provided by bone marrow-derived stromal cells.
989 citations
TL;DR: Evidence is presented that resident mouse peritoneal mast cells constitutively contain large amounts of TNF-α bioactivity, whereas cultured, immature mast cells vary in their T NF-α content, and that release of TTF-α by mast cells may contribute to host defence, the pathophysiology of allergic diseases and other processes dependent on TFB.
Abstract: Tumour necrosis factor-alpha (TNF-alpha)/cachectin is a multifunctional cytokine that has effects in inflammation, sepsis, lipid and protein metabolism, haematopoiesis, angiogenesis and host resistance to parasites and malignancy. TNF-alpha was first described in activated macrophages, but certain mouse or rat mast cell populations (reviewed in refs 4,5) and some in vitro-derived human cells with cytochemical features of mast cells-basophils may also contain products similar to TNF-alpha. Here we present evidence that resident mouse peritoneal mast cells constitutively contain large amounts of TNF-alpha bioactivity, whereas cultured, immature mast cells vary in their TNF-alpha content. IgE-dependent activation of cultured or peritoneal mast cells induces extracellular release of TNF-alpha and augments levels of TNF-alpha messenger RNA and bioactivity. These findings identify mouse mast cells as an important source of both preformed and immunologically inducible TNF-alpha, and suggest that release of TNF-alpha by mast cells may contribute to host defence, the pathophysiology of allergic diseases and other processes dependent on TNF-alpha.
960 citations
TL;DR: It is shown that the death of haemopoietic precursor cells on withdrawal of the relevant CSF is due to active cell death5, or apoptosis, indicating that CSFs promote cell survival by suppression of the process of apoptosis.
Abstract: The survival, differentiation, proliferation and development of haemopoietic precursor cells and the functional activity of mature blood cells are all influenced by colony stimulating factors (CSFs). As haemopoietic cells rapidly die in the absence of appropriate CSF, the promotion of cell survival mediated by CSFs, or growth factors, is fundamental to all the other effects exerted by these factors. This enhancement of cell survival is distinct from the stimulation of proliferation. Here we show that the death of haemopoietic precursor cells on withdrawal of the relevant CSF. is due to active cell death, or apoptosis, indicating that CSFs promote cell survival by suppression of the process of apoptosis. The existence of a positive control mechanism regulating precursor cell survival has important implications both for the regulation of normal haemopoiesis and for tumorigenesis.
956 citations
TL;DR: A novel growth factor, stem cell factor (SCF), for primitive hematopoietic progenitors based on its activity on bone marrow cells derived from mice treated with 5-fluorouracil is identified and sequences of partial SCF cDNAs are presented.
807 citations
TL;DR: Using probes based on the rat sequence, partial and full-length cDNA and genomic clones of human SCF have been isolated and exhibit potent synergistic activities in conjunction with colony-stimulating factors, resulting in increased colony numbers and colony size.
760 citations
TL;DR: The availability of a system for quantitative analysis of the proliferative and differentiative behavior of this newly defined compartment of primitive human hematopoietic cells should facilitate future studies of specific genetic or microenvironmental parameters involved in the regulation of these cells.
Abstract: A major goal of current hematopoiesis research is to develop in vitro methods suitable for the measurement and characterization of stem cells with long-term in vivo repopulating potential. Previous studies from several centers have suggested the presence in normal human or murine marrow of a population of very primitive cells that are biologically, physically, and pharmacologically different from cells detectable by short-term colony assays and that can give rise to the latter in long-term cultures (LTCs) containing a competent stromal cell layer. In this report, we show that such cultures can be used to provide a quantitative assay for human "LTC-initiating cells" based on an assessment of the number of clonogenic cells present after 5-8 weeks. Production of derivative clonogenic cells is shown to be absolutely dependent on the presence of a stromal cell feeder. When this requirement is met, the clonogenic cell output (determined by assessment of 5-week-old cultures) is linearly related to the input cell number over a wide range of cell concentrations. Using limiting dilution analysis techniques, we have established the frequency of LTC-initiating cells in normal human marrow to be approximately 1 per 2 X 10(4) cells and in a highly purified CD34-positive subpopulation to be approximately 1 per 50-100 cells. The proliferative capacity exhibited by individual LTC-initiating cells cultured under apparently identical culture conditions was found to be highly variable. Values for the number of clonogenic cells per LTC-initiating cell in 5-week-old cultures ranged from 1 to 30 (the average being 4) with similar levels being detected in positive 8-week-old cultures. Some LTC-initiating cells are multipotent as evidenced by their generation of erythroid as well as granulopoietic progeny. The availability of a system for quantitative analysis of the proliferative and differentiative behavior of this newly defined compartment of primitive human hematopoietic cells should facilitate future studies of specific genetic or microenvironmental parameters involved in the regulation of these cells.
736 citations
TL;DR: The hypothesis that only fetal HSCs have the capacity to differentiate into V gamma 3+ T cells in the fetal thymic microenvironment is supported and that the developmental potential of H SCs may change during ontogeny is supported.
599 citations
TL;DR: An endothelial cell protein of 45 kDa is identified as the principal receptor associated with this mitogenic effect of erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial Cells.
Abstract: Erythropoietin is known to be a hematopoietic growth factor with a singularly specific action on the proliferation and differentiation of erythroid progenitor cells. We have observed a dose-dependent proliferative action of human recombinant erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial cells. Binding studies with radioiodinated recombinant human erythropoietin revealed a large number (approximately 27,000) of an apparent single class of receptors with an affinity in the 10(-9) M range. Linkage of the radiolabeled ligand to its receptor via a bifunctional crosslinking agent allowed us to identify an endothelial cell protein of 45 kDa as the principal receptor associated with this mitogenic effect of erythropoietin. Recombinant human erythropoietin also enhanced the migration of endothelial cells.
587 citations
TL;DR: Findings suggest that Pgp-1/CD44-related glycoproteins may also be critical for formation of lymphoid and myeloid cells within bone marrow, as well as interactions of cells with the extracellular matrix.
Abstract: A new panel of mAbs was prepared to a stromal cell line known to support lymphocytes in Whitlock-Witte type long-term bone marrow cultures. These antibodies were then screened with a cell adhesion assay and four were selected that inhibited the binding of B lineage cells to stromal cell monolayers. Immunofluorescent and biochemical analyses revealed that these new antibodies detected epitopes of the previously described Pgp-1/CD44 antigen complex. Addition of Pgp-1/CD44 antibodies to Dexter-type long-term bone marrow cultures completely prevented emergence of myeloid cells and they also blocked lymphocyte growth in Whitlock-Witte type cultures. mAbs MEL-14, LFA-1, and CD45R did not inhibit under the same conditions and there was no apparent relationship to Ig isotype. Adherent layers in treated cultures were not unusual in terms of morphology and the antibodies did not affect factor-dependent replication of lymphoid or myeloid progenitor cells. Therefore, the mechanism of inhibition may not involve direct toxicity to precursors or microenvironmental elements. Previous studies in humans and mice have implicated Pgp-1/CD44-related glycoproteins in the migration of peripheral lymphoid cells, as well as interactions of cells with the extracellular matrix. These findings suggest that they may also be critical for formation of lymphoid and myeloid cells within bone marrow.
578 citations
TL;DR: It is demonstrated that single stem cell clones are sufficient to maintain hematopoiesis over the lifetime of an animal and suggested that mono- or oligoclonality may be a hallmark of long-term reconstituted systems.
Abstract: We have analyzed the temporal in vivo fate of 142 individual stem cell clones in 63 reconstituted mice. Long-term sequential analyses of the four major peripheral blood lineages, obtained from animals engrafted with genetically marked stem cells, indicate that developmental behavior is primarily a function of time. As such, the first 4-6 months post-engraftment is characterized by frequent fluctuations in stem cell proliferation and differentiation behavior. Gradually, a stable hematopoietic system emerges, dominated by a small number of totipotent clones. We demonstrate that single stem cell clones are sufficient to maintain hematopoiesis over the lifetime of an animal and suggest that mono- or oligoclonality may be a hallmark of long-term reconstituted systems. A model is proposed, wherein lineage-restricted differentiation and dramatic clonal flux are consequences of mechanisms acting on an expanding pool of totipotent cells and are not indicative of intrinsically distinct stem cell classes.
574 citations
TL;DR: The ability to grow nonhemopoietic, connective tissue cells of marrow origin in vitro and the demonstration that these supported hemopoiesis upon transplantation to ectopic sites in vivo strengthened this premise.
Abstract: Hemopoietic precursors can be identified in a number of tissues, but the bone marrow is the only site in normal adult mammals in which myelopoiesis, erythropoiesis, and lymphopoiesis proceed simultaneously (1). When intrave ' nous injection of hemopoietic precursors occurs as in experimental or clinical bone marrow transplantation, long-term hemo poiesis still establishes only in the bone marrow. Local tissue influences critical for hemopoiesis thus appear to operate primarily in the medullary cavity (2). Such observations have led to considerable interest in understand ing the nature of these influences. A cellular basis for these tissue-specific effects evolved from morphologic studies that demonstrated a close association between blood cells and fixed tissue elements, collectively referred to as stromal cells (3-5). The ability to grow nonhemopoietic, connective tissue cells of marrow origin in vitro and the demonstration that these supported hemopoiesis upon transplantation to ectopic sites in vivo strengthened this premise (6, 7). The application of modern experimental techniques to problems in stromal cell biology has begun to define the mech anisms by which stromal cells mediate their effects. One major advance in the last decade has been the development of cell culture techniques that make it possible to grow selected stromal cells, to study their hemo poietic support capabilities, and to identify and clone genes that encode novel, stromal cell--derived growth and differentiation factors (8, 9). Stro-
TL;DR: It is reported that SCF is expressed during embryogenesis in cells associated with both the migratory pathways and homing sites of melanoblasts, germ cells and haematopoietic stem cells, suggesting that the receptor–ligand system has additional roles in embryogenesis.
Abstract: MICE carrying mutations at the W (Dominant white spotting) and SI (Steel) loci develop abnormalities in three independent systems: neural crest-derived melanocytes, primordial germ cells and haematopoietic stem cells. Consequently, homozygotes of viable mutant alleles have white coats and are sterile and severely anaemic. Tissue recombination studies predict that the W gene is expressed cell autonomously, whereas the product of the SI locus affects the microenvironment in which the stem cells migrate, proliferate and differentiate1–6. The W locus encodes the proto-oncogene c-kit, a member of the tyrosine kinase receptor family7,8.The haematopoietic growth factor SCF (stem cell factor) has been identified as the product of the SI locus and a ligand for c-kit9–11. Here, we report that SCF is expressed during embryogenesis in cells associated with both the migratory pathways and homing sites of melanoblasts, germ cells and haematopoietic stem cells. Both SCF and c-kit are also expressed in a variety of other tissues, including the brain and spinal cord, suggesting that the receptor–ligand system has additional roles in embryogenesis.
TL;DR: The results demonstrate that introduction of an activated abl gene into the appropriate target cell, not the structure of the gene, is the major determinant in myeloid cell specificity.
Abstract: The v-abl gene in Abelson virus induces pre-B-cell lymphoma in mice while the BCR/ABL oncogene is associated with chronic myelogenous leukemia and some cases of acute lymphocytic leukemia in humans. Understanding the mechanisms by which these oncogenes affect various cell types has been hampered by a paucity of experimental systems that reproduce the range of biological effects associated with them. We have developed an experimental system in which murine hematopoietic stem cell populations are infected with either v-abl or BCR/ABL retroviruses and are used to reconstitute lethally irradiated mice. Irrespective of the form of activated abl, greater than 90% of the animals reconstituted with such cells develop tumors. About 50% of them develop a myeloproliferative syndrome that shares several features with the chronic phase of chronic myelogenous leukemia; the remaining animals succumb to pre-B-cell lymphomas. The myeloproliferative syndrome is characterized by large numbers of clonally derived, infected myeloid cells. This model will allow study of the mechanism by which activated abl genes affect hematopoietic precursors in chronic myelogenous leukemia. Furthermore, our results demonstrate that introduction of an activated abl gene into the appropriate target cell, not the structure of the gene, is the major determinant in myeloid cell specificity.
TL;DR: Investigation of this assay system has shown that all three potential sources of stem cells can under appropriate circumstances contribute to long-term hematopoietic regeneration, thus establishing both the competitive pressure of hematoplastic stem cells in the cotransplanted compromised population and in the host, and the need to use genetic markers to track the specific contribution of the injected test cells.
Abstract: Although hematopoiesis is known to originate in a population of very primitive cells with both lymphopoietic and myelopoietic potential, a procedure for enumerating such cells has to date not been available. We now describe a quantitative assay for long-term repopulating stem cells with the potential for reconstituting all hematopoietic lineages. This assay has two key features. The first is the use of competitive repopulation conditions that ensure not only the detection of a very primitive class of hematopoietic stem cells but also the survival of lethally irradiated mice transplanted with very low numbers of such cells. The second is the use of a limiting-dilution experimental design to allow stem cell quantitation. The assay involves transplanting limiting numbers of male "test" cells into lethally irradiated syngeneic female recipients together with 1-2 x 10(5) syngeneic female marrow cells whose long-term repopulating ability has been compromised by two previous cycles of marrow transplantation. The proportion of assay recipients whose regenerated hematopoietic tissues are determined to contain greater than or equal to 5% cells of test cell origin (male) greater than or equal to 5 weeks later is then used to calculate the frequency of competitive repopulating units (CRU) in the original male test cell suspension (based on Poisson statistics). Investigation of this assay system has shown that all three potential sources of stem cells (test cells, compromised cells, and the host) can under appropriate circumstances contribute to long-term hematopoietic regeneration, thus establishing both the competitive pressure of hematopoietic stem cells in the cotransplanted compromised population and in the host, and the need to use genetic markers to track the specific contribution of the injected test cells. Analysis of the frequency of CRU in test marrow suspensions that varied widely in their CRU content gave similar values when endpoints of either 5 or 10 weeks posttransplantation were used and when either recipient marrow or thymus was used to identify progeny populations. In addition, repopulation of marrow and thymus was found to be associated in most mice injected with limiting numbers of test cells. These findings are consistent with the conclusion that the assay is highly selective for a very primitive, totipotent, reconstituting hematopoietic stem cell and should therefore be particularly useful in future gene therapy-oriented research as well as for more basic studies of hematopoietic stem cell regulation and differentiation.
TL;DR: It is shown that GF-1 is expressed in two other haematopoietic lineages, megakaryocytes and bone marrow-derived mast cells, and these findings are consistent with results from haem atopoetic progenitor culture which suggest a relationship between erythroid,Megakaryocytic and mast cell lineages and imply thatGF-1 was expressed in committed multipotential cells and their progeny.
Abstract: The nuclear factor GF-1 (also known as NF-E1, Eryf-1; refs 1-3 respectively) is important in regulation of the transcription of globin and other genes that are specifically expressed in erythroid cells. We have previously shown that GF-1 of both mouse and human origin is a 413-amino-acid polypeptide with two novel zinc-finger domains whose expression is restricted to erythroid cells. Using in situ hybridization of mouse bone marrow cells and northern blot analysis of purified cell populations and permanent cell lines, we show here that GF-1 is expressed in two other hematopoietic lineages, megakaryocytes and bone marrow-derived mast cells. Our findings are consistent with results from hematopoietic progenitor culture which suggest a relationship between erythroid, megakaryocytic and mast cell lineages, and imply that GF-1 is expressed in committed multipotential cells and their progeny. Hence, the mere presence of this transcription factor is unlikely to be sufficient to programme differentiation of a single haematopoietic lineage. GF-1 may regulate the transcription of not only erythroid genes, but also many genes characteristic of megakaryocytes and mast cells, or genes shared among these lineages.
TL;DR: There are two vital classes of engrafting cells: committed progenitors, which provide initial, unsustained engraftment, and PHSC, which produce delayed, but durable, engraft-ment, which allows the lethally irradiated host to survive initial aplasia.
Abstract: Long-term reconstitution of the lymphohaematopoietic cells of a mouse after lethal irradiation requires the transplantation of at least (5-10) x 10(3) bone marrow cells Several cell-separation techniques based on cell-surface characteristics have been used in attempts to identify the pluripotent haematopoietic stem cells (PHSC), and have allowed the long-term engraftment of lethally irradiated mice with an enriched fraction of fewer than 200 marrow cells But these techniques enrich not only for PHSC but also for haematopoietic progenitors, especially day-12 spleen colony-forming units (CFU-S) Although day-12 CFU-S have been postulated to be primitive multipotential haematopoietic progenitors, with day-8 CFU-S representing later, more committed progenitors, recent evidence suggests that neither of these CFU-S represents mouse PHSC Here we report that counterflow centrifugal elutriation, which sorts cells on the basis of size and density, can separate PHSC from these less primitive progenitors The fraction containing the largest cells was enriched for the granulocyte-macrophage colony-forming units (CFU-GM), but gave only transient, early engraftment and was therefore depleted of PHSC The intermediate fraction was enriched for CFU-S, but depleted of CFU-GM Despite being devoid of CFU-GM and CFU-S, the fraction consisting of only morphological lymphocytes gave sustained, albeit delayed, reconstitution of all lymphohaematopoietic cells, and was therefore enriched for PHSC We conclude that there are two vital classes of engrafting cells: committed progenitors, which provide initial, unsustained engraftment, and PHSC, which produce delayed, but durable, engraftment Therefore for late haematological reconstitution, PHSC must be transplanted with a distinguishable source of early engrafting cells, thereby allowing the lethally irradiated host to survive initial aplasia
TL;DR: The Thy/Liv implants provided a microenvironment in which to follow human hematopoietic progenitor cells for multiple lineages, indicating long-term maintenance, in vivo, of human progenitors for the T lymphoid, myelomonocytic, erythroid, and megakaryocytic lineages.
Abstract: Coimplantation of small fragments of human fetal thymus and fetal liver into immunodeficient SCID mice resulted in the formation of a unique structure (Thy/Liv). Thereafter, the SCID-hu mice showed reproducible and long-term reconstitution of human hematopoietic activity. For periods lasting 5-11 mo after transplantation, active T lymphopoiesis was observed inside the grafts and cells that were negative for T cell markers were found to have colony-forming units for granulocyte/macrophage (CFU-GM) and erythroid burst-forming unit (BFU-E) activity in the methylcellulose colony assay. In addition, structures similar to normal human bone marrow were observed inside the Thy/Liv grafts, consisting of blast cells, mature and immature forms of myelomonocytic cells, and megakaryocytes. These data indicate long-term maintenance, in vivo, of human progenitor cells for the T lymphoid, myelomonocytic, erythroid, and megakaryocytic lineages. The role of the implanted fetal liver fragments was analyzed using HLA-mismatched Thy/Liv implants. The HLA type of the liver donor was found on T cells and macrophages in the graft. In addition, cells grown in the methylcellulose colony assay and cells in a bone marrow-like structure, the "thymic isle," expressed the HLA type of the liver donor. Thus, the Thy/Liv implants provided a microenvironment in which to follow human hematopoietic progenitor cells for multiple lineages. The formation of the Thy/Liv structures also results in a continuous source of human T cells in the peripheral circulation of the SCID-hu mouse. Though present for 5-11 mo, these cells did not engage in a xenograft (graft-versus-host) reaction. This animal model, the first in which multilineage human hematopoietic activity is maintained for long periods of time, should be useful for the analysis of human hematopoiesis in vivo.
TL;DR: It is established that bcr‐abl confers a proliferative advantage on diverse haemopoietic cells but complete transformation probably involves additional genetic changes.
Abstract: The chromosome translocation forming the hybrid bcr-abl gene is thought to be the initiating event in chronic myeloid leukaemia (CML) and some cases of acute lymphoblastic leukaemia. To assess the impact of bcr-abl upon haemopoiesis, lethally irradiated mice were reconstituted with bone marrow cells enriched for cycling stem cells and infected with a bcr-abl bearing retrovirus. The mice developed several fatal diseases with abnormal accumulations of macrophage, erythroid, mast and lymphoid cells, and marked strain differences in disease distribution and kinetics. Some mice exhibited more than one neoplastic cell type and, in some instances, these were clonally related, indicating that a progenitor or stem cell had been transformed. While classical CML was not observed, the macrophage tumours were accompanied by a mild CML-like syndrome, probably due to myeloid growth factor production by tumour cells. The erythroid and mast cell diseases were rarely transplantable, in contrast to the macrophage tumours and lymphomas, but all disease types displayed limited clonality. These results establish that bcr-abl confers a proliferative advantage on diverse haemopoietic cells but complete transformation probably involves additional genetic changes.
TL;DR: The observations provide further insight into the heterogeneous nature of CFU-S and directly demonstrate that multipotent hematopoietic stem cells are heterogeneous with regard to their clonogenic capacities.
Abstract: The fluorescent vital dye rhodamine 123 (Rh-123), which preferentially accumulates in mitochondrial membranes, can be used as a probe to indicate mitochondrial and hence cellular activity. In this study, mouse bone marrow hematopoietic stem cells were subdivided into Rh-123lo, Rh-123med, and Rh-123hi populations. The Rh-123lo (resting) population was significantly enriched in cells with a higher proliferative potential compared to the Rh-123hi (activated) population. The resting population exhibited a 20-fold greater ability to differentiate into splenic colony-forming units (CFU-S) relative to the activated population, whereas the activated population contained about 4-fold more day 13 CFU-S on primary transfer relative to the resting population. The two populations produced morphologically distinct splenic colonies; however, the frequency and morphology of in vitro colonies were very similar. Only the resting population provided sufficient stem cells to transfer long-term hematopoietic repopulation to secondary recipient animals after lethal irradiation. On a single cell level, the resting and activated populations exhibited an equivalent ability to differentiate into lymphoid and myeloid progeny. These observations provide further insight into the heterogeneous nature of CFU-S and directly demonstrate that multipotent hematopoietic stem cells are heterogeneous with regard to their clonogenic capacities.
TL;DR: The similarity of these findings to those of multicentric Castleman's disease, taken together with the observation that lymph nodes from these patients elaborate large amounts of this cytokine, suggest that the inappropriate synthesis of IL-6 has a primary role in the pathogenesis of this systemic lymphoproliferative disorder.
Abstract: Interleukin 6 (IL-6) is an important regulator of the acute phase response, T cell function, and terminal B cell differentiation. Excessive or inappropriate production of this cytokine may be involved in a variety of autoimmune and neoplastic disorders. To investigate the consequences of dysregulated synthesis of IL-6 in vivo, a high-titer recombinant retroviral vector produced in psi-2 packaging cells was used to introduce the coding sequences of murine IL-6 into mouse hematopoietic cells. Congenitally anemic W/Wv mice reconstituted with bone marrow cells transduced with the retroviral vector developed a syndrome characterized by anemia, transient granulocytosis, hypoalbuminemia, and polyclonal hypergammaglobulinemia, with marked splenomegaly and peripheral lymphadenopathy. Extensive plasma cell infiltration of lymph nodes, spleen, liver, and lung was noted. The similarity of these findings to those of multicentric Castleman's disease, taken together with the observation that lymph nodes from these patients elaborate large amounts of this cytokine, suggest that the inappropriate synthesis of IL-6 has a primary role in the pathogenesis of this systemic lymphoproliferative disorder.
TL;DR: A mast cell proliferation assay is used to purify a 30 kd protein, designated KL, from conditioned medium of Balb/3T3 fibroblasts to apparent homogeneity and KL stimulates the proliferation of normal bone marrow derived mast cells but not mast cells from W mice, although both normal and mutant mast cells respond similarly to IL‐3.
Abstract: The c-kit proto-oncogene encodes a transmembrane tyrosine kinase receptor for an unidentified ligand and is allelic with the murine white-spotting locus (W) W mutations affect melanogenesis, gametogenesis and hematopoiesis during development and in adult life Cellular targets of W mutations in hematopoiesis include distinct cell populations in the erythroid and mast cell lineages as well as stem cells In the absence of interleukin-3 (IL-3) mast cells derived from normal mice but not from W mutant mice can be maintained by co-culture with 3T3 fibroblasts Based on the defective proliferative response of W mast cells in the 3T3 fibroblast co-culture system it had been proposed that fibroblasts produce the c-kit ligand We have used a mast cell proliferation assay to purify a 30 kd protein, designated KL, from conditioned medium of Balb/3T3 fibroblasts to apparent homogeneity KL stimulates the proliferation of normal bone marrow derived mast cells but not mast cells from W mice, although both normal and mutant mast cells respond similarly to IL-3 Connective tissue-type mast cells derived from the peritoneal cavity of normal mice were found to express a high level of c-kit protein on their surface and to proliferate in response to KL The effect of KL on erythroid progenitor cells was investigated as well In combination with erythropoietin, KL was found to stimulate early erythroid progenitors (BFU-E) from fetal liver and spleen cells but not from bone marrow cells of adult mice and from fetal liver cells of W/W mice(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Proteasome expression was also greatly increased in normal blood mononuclear cells during blastogenic transformation induced by phytohemagglutinin; their expression increased in parallel with induction of DNA synthesis and returned to the basal level with progress of the cell cycle.
Abstract: Proteasomes are eukaryotic ring-shaped or cylindrical particles with multicatalytic protease activities. To clarify the involvement of proteasomes in tumorigenesis of human blood cells, we compared their expression in human hematopoietic malignant tumor cells with that in normal peripheral blood mononuclear cells. Immunohistochemical staining showed considerably increased concentrations of proteasomes in leukemic cells from the bone marrow of patients with various types of leukemia and the predominant localization of these proteasomes in the nuclei. Moreover, enzyme immunoassay and Northern blot analysis indicated that the concentrations of proteasomes and their mRNA levels were consistently much higher in a variety of malignant human hematopoietic cell lines than in resting peripheral lymphocytes and monocytes from healthy adults. Proteasome expression was also greatly increased in normal blood mononuclear cells during blastogenic transformation induced by phytohemagglutinin; their expression increased in parallel with induction of DNA synthesis and returned to the basal level with progress of the cell cycle. Thus, abnormally high expression of proteasomes may play an important role in transformation and proliferation of blood cells and in specific functions of hematopoietic tumor cells.
01 Jan 1990
TL;DR: Injuries to tissue, whether due to mechanical, chemical, immunological, or thermal insults, initiate an orderly but complex series of cellular and biochemical interactions that lead to the formation of new tissue and the eventual repair of the wound.
Abstract: Injuries to tissue, whether due to mechanical, chemical, immunological, or thermal insults, initiate an orderly but complex series of cellular and biochemical interactions that lead to the formation of new tissue and the eventual repair of the wound. The cellular components of this pathway include hematopoietic cells such as platelets, polymorphonuclear leukocytes, lymphocytes, and monocytes, and mesenchymal cells such as fibroblasts and endothelial cells. These cells migrate to the site of tissue damage in a sequence determined by soluble factors that are released at the site of injury through a wide variety of mechanisms. Among these are tissue breakdown, blood coagulation, and cellular release. Each cell type has a specific function to perform such as degradation and resorption of damaged tissue, protection against infection, or deposition of new extracellular matrix.
TL;DR: It is shown that among the peripheral blood cells during G-CSF therapy are substantial numbers of primitive stem cells capable of reconstituting the hematopoietic system in the long term and making a contribution to the lymphoid populations of the thymus, in radiation ablated recipients.
TL;DR: In this paper, two classes of activating mutations in the erythropoietin receptor (EPOR) were described, one point mutation in the exoplasmic domain enabling it to induce hormone-independent cell growth and tumorigenesis after expression in nontumorigenic, interleukin-3-dependent haematopoietic cells.
Abstract: The receptors for erythropoietin and other cytokines constitute a new superfamily. They have no tyrosine-kinase or other enzyme motif and their signal-transducing mechanism is unclear. Here we describe two classes of activating mutations in the erythropoietin receptor (EPOR). A single point mutation in the exoplasmic domain enables it to induce hormone-independent cell growth and tumorigenesis after expression in nontumorigenic, interleukin-3-dependent haematopoietic cells. A C-terminal truncation in the cytoplasmic domain of the EPOR renders the receptor hyperresponsive to erythropoietin, but is insufficient to induce hormone-independent growth or tumorigenicity. The activating point mutation retards intracellular transport and turnover of the receptor. These alterations in metabolism and tumorigenicity caused by the EPOR with activating point mutations are similar to those observed in erythropoietin-independent activation of the wild type EPOR by association with gp55, the Friend spleen focus-forming virus glycoprotein.
TL;DR: The presence of CD45RO and the lack ofCD45R on human cells capable of initiating hemopoiesis in the long-term marrow culture system correspond to the reported lack of CD 45R on transplantable hemopOietic stem cells in rodents and may be a useful addition to strategies for human stem cell purification, or for purging CD45R+ leukemic cells.
Abstract: We have found that the small population of cells in human marrow that are characterized by their expression of CD34 can be readily subdivided into two apparently nonoverlapping subpopulations of approximate equal size, one expressing CD45RO and one CD45R. Functional studies of these subpopulations revealed that all of the primitive erythroid colony-forming cells (BFU-E) are CD34+ CD45RO+. Similarly, more primitive cells that give rise to both erythroid and granulopoietic colony-forming cells after being maintained for 5 wk on confluent irradiated long-term marrow culture feeder layers, also show this phenotype. In contrast, most granulopoietic colony-forming cells are CD34+ CD45RO- cells. The differential expression of CD45 isoforms on distinct functional subpopulations of hemopoietic cells is consistent with the concept that these molecules play an important role in the differentiation or activation of primitive, normally quiescent, hemopoietic cells. The presence of CD45RO and the lack of CD45R on human cells capable of initiating hemopoiesis in the long-term marrow culture system correspond to the reported lack of CD45R on transplantable hemopoietic stem cells in rodents and may be a useful addition to strategies for human stem cell purification, or for purging CD45R+ leukemic cells.
TL;DR: These results, along with previous studies, suggest that MIP-1 alpha, -1 beta, and -2 may have direct myelopoietic enhancing activity for mature progenitors, while MIP -1 alpha may havedirect suppressing activity for more immature progenitor.
TL;DR: A model in which indirect, local modulation of both positive and negative regulatory factors via effects on mesenchymal elements determines the rate of turnover of adjacent populations of very primitive hematopoietic cells that are normally maintained in a quiescent state in vivo is suggested.
Journal Article•
TL;DR: Results indicate that the PSCs were unaffected after a single treatment with 5-FU, although they were concentrated tenfold, and their relative repopulating ability was not comprised by the additional stress of sublethal irradiation.
Journal Article•
TL;DR: It is reported that astrocytes may also contribute to the macrophage response observed in inflammatory and degenerative diseases of the brain.
Abstract: Astrocytes may play a central role in regulation of immune mediated processes in the central nervous system. By their inducible expression of MHC class II Ag and secretion of cytokines they may propagate expansion and activation of T and B lymphocytes invading the brain tissue. Here we report that astrocytes may also contribute to the macrophage response observed in inflammatory and degenerative diseases of the brain. Murine astrocytes secrete granulocyte-macrophage CSF (GM-CSF) as evidenced by induction of colony formation in bone marrow cells and growth of FDC-P1 cells. Both effects are neutralized with anti-GM-CSF- but not with anti-IL-3-antibodies. Some residual activity detected in the bone marrow assay after antibody treatment can be explained by concomitant production of granulocyte CSF (G-CSF). The mRNA of both G- and GM-CSF are identified by Northern blots in astrocytes. Furthermore, mRNA for IL-1 alpha and IL-1 beta are detected in comparable amounts in astrocytes and brain macrophages, the latter, however, comprising much more potent sources of TNF-alpha.