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Biomedical subjects

E Vellenga

Publications and source records attributed to E Vellenga.

At least 181 records · Page 10Linked to original sources
PubMed1991

Erythroid progenitors in polycythemia vera demonstrate a different response pattern to IL-4 compared to the normal BFU-E from peripheral blood.

Human recombinant interleukin 4 (IL-4) was studied for its effects on erythroid burst-forming units (BFU-E) from normal peripheral blood and from patients with polycythemia vera (PV). IL-4 enhanced the proliferation of normal peripheral blood BFU-E (183% +/- 20% enhancement), whereas in the presence of interleukin 3 (IL-3) no further augmentation was noticed. The IL-4-mediated effects were independent of the absence or presence of adherent cells, B cells, or T cells. These data are in contrast with results obtained from normal human bone marrow cells, in which IL-4 antagonized the enhancing effects of IL-3. In PV a different response pattern was observed. The effects of IL-4 on the erythropoietin (Epo)-independent BFU-E were variable. In five PV patients no suppressive or enhancing effects of IL-4 were observed, whereas in two additional patients a significant decline in the Epo-independent BFU-E was noted. In the presence of IL-3, IL-4 significantly antagonized the IL-3-supported Epo-independent BFU-E in all patients (272% +/- 57% vs 187% +/- 49% enhancement, p less than 0.05). In contrast, IL-4 did not modify the IL-3-supported Epo-dependent BFU-E. In summary, these data suggest a difference between the normal and PV peripheral blood BFU-E. The Epo-dependent erythroid progenitors in PV patients showed a response pattern with IL-3 and IL-4 comparable to that of normal peripheral blood BFU-E, whereas the Epo-independent erythroid progenitors behaved like normal human bone marrow BFU-E, suggesting a shift in the stem cell compartment in PV. This is further supported by the finding that erythroid colony-forming units (CFU-E), normally only present in the bone marrow, could be cultured from the peripheral blood of PV patients in the presence or absence of Epo.

B-Lymphocytes↗
PubMed1991

Expression and regulation of IL-4 receptors on human monocytes and acute myeloblastic leukemic cells.

Evidence is presented that human monocytes and acute myeloblastic leukemic (AML) cells contain both high and low affinity binding sites for interleukin-4 (IL-4). On monocytes 183 +/- 132 high affinity binding sites per cell with a Kd of 60 +/- 29 pM and 1500 +/- 600 low affinity receptors with a Kd of 2.3 +/- 0.4 nM (X +/- S.D., n = 6) could be demonstrated. On AML cells (n = 11) a comparable number and binding affinity of IL-4 receptors were observed (77 +/- 36 high affinity receptors with Kd 72 +/- 31 pM and 2400 +/- 1000 low affinity receptors with Kd of 2.2 +/- 0.7 nM). In addition, no cross-competition was shown between radiolabeled IL-4 and IL-1-alpha, IL-3, IL-6, IL-7, G-CSF, and GM-CSF. Both types of receptors on monocytes as well as on leukemic blasts could be down-modulated in a similar fashion by IL-4 and activators of protein kinase C (PKC), but not by the calcium ionophore A23187. The down-modulation by PKC activators was caused by an increased internalization, degradation and release of radiolabeled IL-4 in the medium. Finally, the functionality of the IL-4 receptors were tested on AML cells with a 3H-thymidine proliferation assay. In 8/11 cases IL-4 affected AML proliferation. These data demonstrate two different binding sites for IL-4 on normal and leukemic cells, which can be modulated by external activation signals in an analogous way.

Cell Division↗
PubMed1991

Tumour necrosis factor (cachectin) and other cytokines in septic shock: a review of the literature.

The role of bacterial endotoxin in the pathogenesis of septic shock has been studied extensively. Endotoxin does not seem to exert most of its effects on the host directly, but rather it elicits the production of host factors that may in turn lead to shock and death. These factors, called cytokines, appear to be produced by cells of haematopoietic origin such as macrophages/monocytes, but can also be produced by other cells such as endothelium and fibroblasts. Three important cytokines associated with septic shock are tumour necrosis factor/cachectin (TNF), interleukin 1 (IL-1) and interleukin 6 (IL-6). The macrophage-derived TNF has been implicated as the most important host mediator in the pathogenesis of septic shock. TNF, alone or together with endotoxin or IL-1, is capable of inducing lethal shock and tissue injury resembling that of septic shock. It has also been suggested that IL-6 is involved in the pathogenesis of septic shock. The major biologic activities of IL-6 include B-cell differentiation and induction of the acute-phase proteins. In the present paper, reports addressing the current understanding of the biological, regulatory and clinical aspects of these cytokines are reviewed.

Gene Expression Regulation↗
PubMed1991

Recombinant human erythropoietin in patients with myelodysplastic syndromes.

As anemia is frequently the main problem in myelodysplastic syndromes (MDS), we studied the efficacy of human erythropoietin (rhEpo) in stimulating the erythroid lineage in 14 patients, starting with 40 U/kg three times a week and doubling the dose every 6 weeks until a response was observed. The highest doses administered were 80 (n = 1), 160 (n = 4), 320 (n = 8) and 640 U/kg (n = 1). One patient (refractory anemia with an excess of blasts, RAEB) showed an increase of hemoglobin, white blood cells and platelets with 80 U/kg rhEpo. However, this patient developed acute leukemia while on therapy. Two other patients (RAEB and RAEB in transformation) also transformed to acute leukemia. In the other 11 patients no response was observed. There was no correlation between in vitro culture data and in vivo responsiveness. The treatment was well tolerated and no nonhematological side effects were observed. From this study we conclude that rhEpo, even when given at high doses, has a low response rate in patients with MDS. Further investigation is needed in order to clarify whether rhEpo increases the potential risk of transformation to acute leukemia.

Adult↗
PubMed1990

Divergent effects of interleukin-4 (IL-4) on the granulocyte colony-stimulating factor and IL-3-supported myeloid colony formation from normal and leukemic bone marrow cells.

Human recombinant interleukin-4 (IL-4) was studied for its effects on myeloid progenitor cells from normal and leukemic bone marrow cells in the presence and absence of additional growth factors. IL-4 itself did not support myeloid cluster or colony formation (CFU-GM). However, cultures supplied with IL-4 (300 U/mL) and IL-3 demonstrated a significant decline in myeloid colony numbers (CFU-GM) compared with the effects of IL-3 alone: (48 +/- 27 v 88 +/- 27 CFU-GM/10(5) MNC). In contrast, IL-4 augmented the G-CSF-supported CFU-GM: (80 +/- 31 v 148 +/- 52 CFU-GM/10(5) MNC). The effects of IL-4 were not mediated by accessory cells because similar results were obtained with and without T-cell, B-cell, or adherent depleted cell fractions. Morphologic analysis of clusters (day 7) and the colonies (day 14) demonstrated that IL-4 enhanced myeloid colony formation in the presence of G-CSF, whereas the cultures supplied with IL-3 and IL-4 did not show a lineage-restricted decline of CFU-GM. A heterogeneity in growth response was observed in the leukemic counterpart. With the 3H-thymidine proliferation assay, IL-4 augmented the G-CSF-induced proliferation of acute myeloid leukemic (AML) cells in 4 of the 12 cases, while the IL-3-supported proliferation was antagonized in 3 of the 12 cases. In the blast colony assay, IL-4 suppressed the IL-3-supported AML-CFU in the majority of cases, but enhanced the G-CSF stimulated AML-CFU in 3 of 6 cases. These data demonstrate divergent effects of IL-4 on the normal myeloid progenitor cell in the presence of IL-3 or G-CSF, while a variability in responsiveness is observed in the leukemic counterpart.

Bone Marrow Cells↗
PubMed1990

The role of colony-stimulating factors in acute leukemia.

This article summarises the effects of colony-stimulating factors and related molecules on leukemia blasts by focussing on autocrine and paracrine growth control. This information may lead to a better understanding of the pathobiology of this highly malignant disorder, and may have therapeutic implications.

Colony-Stimulating Factors↗
PubMed1990

Efficacy and tolerability of recombinant human granulocyte-macrophage colony-stimulating factor in patients with chemotherapy-related leukopenia and fever.

30 patients with chemotherapy-related leukopenia (white cells 1.0 x 10(9)/l or lower) and fever (temperature 38.5 degrees C or higher) were treated in a double-blind randomised trial with standard antibiotics and 7 days of intravenously administered recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF, 2.8 micrograms/kg per day) or placebo. GM-CSF administration resulted in a faster percentage increase of peripheral neutrophil count after 2 and 3 days of treatment, except in patients treated with ablative chemotherapy and autologous bone-marrow transplantation. However, GM-CSF did not shorten the period of fever or antibiotic administration. No side-effects were observed; in particular tumour necrosis factor alpha and interleukin-6 did not increase in the 5 GM-CSF patients tested. These data suggest that a subgroup of patients with chemotherapy-related leukopenia and fever may benefit from GM-CSF treatment in view of the observed effects on neutrophil count.

Adolescent↗
PubMed1990

Interleukin-4 suppresses the interleukin-3 dependent erythroid colony formation from normal human bone marrow cells.

Human recombinant interleukin 4 (IL-4) was studied for its effects on the erythroid burst forming unit (BFU-E) from human bone marrow cells. IL-4 alone neither supports nor suppresses the erythropoietin (Epo)-dependent colony formation. Different results were obtained when IL-4 was combined with interleukin-3 (IL-3) in the presence of Epo. IL-4 suppressed the IL-3 supported erythroid colony formation in all cases (an increase of 58 +/- 8% with IL-3 versus an increase of 14 +/- 7% with IL-3 plus IL-4, n = 8). This antagonizing effect was dependent on the continuous presence of IL-4 in the culture medium, but was independent of adherent cells, B-, T-cells, or the presence of serum in the culture medium. Finally, the effects of IL-4 and IL-3 were studied on the 'Epo-independent' BFU-E by adding Epo on day 3. A decline of the IL-3 supported BFU-E was observed in the presence of IL-4 but the degree of reduction was equivalent to the results obtained when Epo was supplied at day 0. These findings indicate that IL-4 acts as suppressive growth factor for the IL-3 supported erythroid colony formation from human bone marrow cells.

Bone Marrow Cells↗
PubMed1989

Quantitation of plasma levels of tetranectin--effects of oral contraceptives, pregnancy, treatment with L-asparaginase and liver cirrhosis.

Tetranectin is a tetrameric protein that binds to kringle 4 of plasminogen. Increase of electrophoretic mobility of the otherwise slowly migrating tetranectin in the presence of ethylenediaminetetraacetate was used to develop a reproducible electroimmunoassay to quantify plasma levels. Plasma levels in normals were found within narrow limits of 100 +/- 16 (SD)%, (100% = 0.15 mumol/l). There was no difference between males and females, smokers and non-smokers, and there were no significant changes with age from 20 to 49 years. Patients with severe liver cirrhosis showed a large variation in plasma tetranectin levels but no systematic or average reduction, in contrast to strong reductions in plasma levels of other proteins. Patients treated with L-asparaginase showed a gradual reduction in time in plasma levels of various proteins, though tetranectin showed no significant reduction. It is concluded that tetranectin can be assayed reproducibly in plasma and has a well regulated plasma level. This level is not sensitive to conditions with reductions in synthesis of many proteins, such as during cirrhosis of the liver and during L-asparaginase therapy. The reductions in plasma levels during the use of oral contraceptives and pregnancy indicate involvement of sex steroids in the metabolism of tetranectin.

Adolescent↗
PubMed1989

In polycythemia vera human interleukin 3 and granulocyte-macrophage colony-stimulating factor enhance erythroid colony growth in the absence of erythropoietin.

To further define the growth factors required for the in vitro proliferation of erythroid progenitors in polycythemia vera (PV), we have compared the ability of interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) to support the growth of erythropoietin (Epo)-dependent and -independent erythroid colony formation. By using nonadherent mononuclear cells from peripheral blood, Epo-dependent colony formation was enhanced by IL-3 and GM-CSF in PV patients. Comparable results were obtained with normal erythroid progenitors. Augmenting effects of IL-3 and GM-CSF were observed on spontaneous erythroid colony formation, i.e., erythroid colony formation in the absence of exogenous supplied Epo. This was not due to a small amount of Epo in the culture media because an anti-Epo antibody did not prevent endogenous colony formation, nor did it prevent the enhancing effects of IL-3. Finally it was observed that in contrast to IL-3, monocyte depletion was required for the enhancing effects of GM-CSF on erythroid colony formation. These results provide evidence that endogenous colony formation in PV is independent of Epo but can be augmented by IL-3 or GM-CSF.

Cells, Cultured↗
PubMed1988

Expression of the macrophage colony-stimulating factor and c-fms genes in human acute myeloblastic leukemia cells.

Macrophage colony-stimulating factor (CSF-1; M-CSF) is a growth factor required for growth and differentiation of mononuclear phagocytes. The effects of CSF-1 are mediated through binding to specific, high-affinity surface receptors encoded by the c-fms gene. CSF-1 and c-fms gene expression was investigated in fresh human acute myeloblastic leukemic cells by Northern blot hybridization using cDNA probes. 4.0-kb CSF-1 transcripts were detected in 10 of 17 cases of acute myeloblastic leukemia (AML), while c-fms transcripts were detected in 7 of 15. Coexpression of CSF-1 and c-fms was observed in five cases, and in five other cases neither gene was expressed. In situ hybridization demonstrated that transcripts for CSF-1 were present in 70-90% of cells in each of three cases studied while c-fms mRNA was detected in 40-70% of cells. The constitutive expression of CSF-1 transcripts was associated with production of CSF-1 protein, although detectable amounts of CSF-1 were not secreted unless the cells were exposed to phorbol ester. These results demonstrate that leukemic myeloblasts from a subset of patients with AML express transcripts for both the CSF-1 and CSF-1 receptor genes, often in the same leukemic cells in vitro.

Colony-Stimulating Factors↗
PubMed1988

Independent regulation of M-CSF and G-CSF gene expression in human monocytes.

The macrophage and granulocyte colony-stimulating factors, M-CSF and G-CSF, act in vitro to induce proliferation and differentiation of monocyte and granulocyte progenitor cells, respectively. We show here that both of these CSFs can be produced by stimulated human blood monocytes, but the M-CSF and G-CSF genes are independently regulated. Recombinant human interleukin-3 (IL-3) and GM-CSF primarily induce expression of the M-CSF gene and secretion of M-CSF, whereas bacterial lipopolysaccharide primarily induces expression of the G-CSF gene and secretion of G-CSF. These results suggest that under different conditions of in vitro stimulation the monocyte secretes factors that could lead selectively to either granulocyte or monocyte production.

Cell Adhesion↗
PubMed1988

Human granulocyte-monocyte colony-stimulating factor and interleukin 3 stimulate monocyte cytotoxicity through a tumor necrosis factor-dependent mechanism.

Human colony-stimulating factors (CSF) exert multiple effects on the proliferation, differentiation, and function of myeloid lineage cells. In this study, the effects of three recombinant human CSFs (granulocyte-monocyte CSF [GM-CSF], interleukin 3 [IL-3], and granulocyte CSF [G-CSF]) on antibody-independent monocyte tumoricidal activity were investigated by using WEHI 164 fibrosarcoma cells as monocyte-sensitive targets. None of the CSFs directly induced monocyte cytotoxicity, although both GM-CSF and IL-3 were found to significantly enhance monocyte killing in response to a second stimulatory event (endotoxin). No effect was seen with G-CSF. Antitumor necrosis factor antibody completely abolished CSF-enhanced monocyte cytotoxicity, which suggests that this effect was mediated through increased release of tumor necrosis factor (TNF). As previously shown for GM-CSF, IL-3 was found to induce cytoplasmic accumulation of TNF messenger RNA (mRNA) after 18 hours of exposure. These results suggest that GM-CSF and IL-3 may stimulate monocyte killing indirectly by enhancing expression of TNF mRNA, thereby leading to augmented TNF protein secretion in response to a second activation signal.

Biomechanical Phenomena↗
PubMed1987

Lymphocyte subpopulations in peripheral blood and bone marrow in patients with idiopathic myelofibrosis.

In 8 patients with idiopathic myelofibrosis (IM) T and B cells were studied in view of the possibility that immunological dysfunctions are involved in initiating or contributing to the bone marrow fibrosis. In peripheral blood the absolute numbers of E-SRBC and OKT3+ lymphocytes were significantly reduced; in addition a significant decline was observed in the proportion and absolute numbers of OKT8+ cells, resulting in a reversed Leu-3a/OKT8 ratio. An impaired B cell function was observed in 4 of the 8 patients, characterized by a disturbed in vitro pokeweed mitogen stimulated immunoglobulin synthesis and low serum immunoglobulin levels. Immuno-histological studies of the bone marrow demonstrated a scarcity of T cells but normal numbers of B cells. However, no correlation was noted between the observed deviations of B and T cells and the degree of bone marrow fibrosis determined by means of bone marrow histology and serum procollagen-III levels. These data are not sufficient to support the hypothesis that immunological changes in IM are primarily involved in the process of bone marrow fibrosis.

Adult↗
PubMed1987

Different repopulation kinetics of erythroid (BFU-E), myeloid (CFU-GM) and T lymphocyte (TL-CFU) progenitor cells after autologous and allogeneic bone marrow transplantation.

Marrow recovery of erythroid (BFU-E), myeloid (CFU-GM) and T-lymphocyte (TL-CFU) progenitor cells was studied at various time intervals after autologous bone marrow transplantation in 10 patients with acute myeloid leukaemia in remission. These data were compared with those in 14 recipients of T-cell depleted allogeneic marrow grafts. The results indicate markedly different repopulation kinetics of BFU-E, CFU-GM and TL-CFU after autologous and allogeneic bone marrow transplantation. Following autografting reduced numbers of BFU-E and CFU-GM were always present at 2 months after transplantation. Between 2-6 and 6-24 months a gradual increase occurred, although reduced BFU-E and CFU-GM values were still noted in 50% of the cases in spite of normal bone marrow cellularity and restoration of peripheral blood counts. In contrast, in the allograft recipients normal BFU-E numbers appeared within 2 months after transplantation. In addition, CFU-GM values had become normal in 35% of the tests performed at 1-2 months and respectively in 66% and 100% at 2-6 and 6-24 months. The recovery pattern of TL-CFU differed from that of the other haemopoietic progenitor cells. TL-CFU showed a fast recovery, i.e. within 1 month after autologous bone marrow transplantation which was much more rapid than that of BFU-E and CFU-GM. After allografting, however, TL-CFU regenerated at a slower rate and reached normal levels between 2 and 6 months after transplantation. We suggest that the delayed restoration of myeloid and erythroid progenitor cells after autologous transplantation is related to a proliferative defect of the graft as a result of the preceding cytotoxic chemotherapy, the underlying malignant disease and/or cryopreservation. The slower recovery of the T lymphocyte precursors after allografting might be due to the immunological interactions between graft and host, the immuno-suppressive therapy and/or the in vitro T cell depletion of the graft.

Blood Cell Count↗