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E B Smeland

Publications and source records attributed to E B Smeland.

At least 19 recordsLinked to original sources
PubMed1995

All-trans- and 9-cis-retinoic acid inhibit growth of normal human and murine B cell precursors.

In the present paper we demonstrate that physiologic levels (10 nM) of both all-trans- and 9-cis-retinoic acid (RA) are potent inhibitors of the growth of human as well as murine B cell precursors in vitro. Ten nanomolar concentrations of all-trans- and 9-cis-RA reduced the DNA synthesis ([3H]thymidine uptake) of human B cell precursors (CD19+ IgM-) stimulated with O-tetradecanoylphorbol-13-acetate and ionomycin by approximately 55% and 70%, respectively. Human B cell precursors stimulated with low m.w. B cell growth factor were also inhibited by RA. Ten nanomolar concentrations of either isoform of RA reduced DNA synthesis by approximately 50%. No effect of RA on differentiation to sIgM positive cells was noted. The potent growth-inhibiting effect of RA on human B cell precursors was confirmed in the murine cell system. B lymphopoiesis from murine hematopoietic precursors (Lin-B220(+)-containing cells) was induced by stimulation with IL-7. Concentrations of all-trans- and 9-cis-RA as low as 10 pM reduced the colony-forming ability of the IL-7-stimulated Lin-B220(+)-containing cells. Ten nanomolar concentrations of either isoform reduced colony formation by approximately 60%. RA was not toxic to the cells, as the inhibition of colony formation after 24 h was reversible at concentrations as high as 1 microM. The growth-inhibiting effect of RA was directly mediated, as revealed by single cell analysis of the Lin-B220(+)-containing cells. Thus, vitamin A appears to have an important role in regulation of B lymphopoiesis.

Animals↗
PubMed1995

TGF-beta 1 and cyclic AMP promote apoptosis in resting human B lymphocytes.

TGF-beta and agents that elevate intracellular cAMP levels are potent inhibitors of B cell activation in vitro and have been shown to arrest stimulated B cells in the G1 phase of the cell cycle. We tested the effects of TGF-beta 1 and the cAMP-inducing agent, forskolin, on the viability of resting B cells from human peripheral blood, and found that both agents caused a significant, dose-dependent increase in cell death relative to spontaneous death in medium alone, as measured by vital dye staining with propidium iodide. Apoptosis was shown to be the overall mode of death by demonstrating DNA fragmentation using DNA nick end labeling and by verifying the characteristic morphologic changes. In contrast with TGF-beta 1 and forskolin, various B cell activation stimuli generally inhibited spontaneous apoptosis of resting cells. The most potent effects were observed with IL-4 and the phorbol ester, O-tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C. IL-4 also partly inhibited TGF-beta 1 and forskolin-induced apoptosis. In contrast, TPA completely reversed cell death in forskolin-treated cultures, but had no effect on TGF-beta 1-induced apoptosis, indicating that TGF-beta 1 and forskolin promote apoptosis by different mechanisms. The relative protein expression of bcl-2, a proto-oncogene that inhibits apoptosis, was unaltered by the apoptotic as well as the survival stimuli tested, suggesting that apoptosis was regulated by a bcl-2-independent mechanism. We conclude that apoptosis is a regulated phenomenon in resting human B cells. Furthermore, TGF-beta and cAMP may inhibit B cell responses not only by blocking cell cycle progression in activated cells, but also by inducing apoptosis in resting cells.

Antigens, CD↗
PubMed1994

Cross-linking of CD53 promotes activation of resting human B lymphocytes.

The CD53 pan-leukocyte glycoprotein is a member of the recently described tetraspan family of cell membrane proteins. The structure and functional characteristics of these molecules indicate that they may play important roles in transmembrane signaling in different cells. Recently, it was reported that cross-linking of CD53 on human B cells led to an increase in cytoplasmic calcium fluxes. In the present study, we wished to further explore the possible role of CD53 in functional B cell responses. Cross-linking of CD53 with the use of the mAb MEM-53 and a polyclonal sheep anti-mouse Ig promoted activation of resting B cells into the G1 phase of the cell cycle as judged by increased expression of the early activation Ag CD69, increases in cellular volume, RNA synthesis, and c-myc protein levels, and enhanced binding of 7-aminoactinomycin D. In contrast, MEM-53 alone had no detectable effects. Cross-linking of anti-CD53 induced negligible S phase entry in the absence of other stimuli. However, cytokines, in particular IL-2 and IL-4, potentiated the DNA synthesis induced by cross-linking of CD53. Furthermore, cross-linking of the CD53 Ag induced Ig production in the presence of T cell supernatant. Taken together, the data suggest that CD53 plays an important functional role in B cell activation and differentiation.

Antigens, CD↗
PubMed1994

All-trans retinoic acid directly inhibits granulocyte colony-stimulating factor-induced proliferation of CD34+ human hematopoietic progenitor cells.

In this study we examine the effects of retinoids on purified CD34+ human hematopoietic progenitor cells. All-trans retinoic acid inhibited granulocyte colony-stimulating factor (G-CSF)-induced proliferation of CD34+ cells in short-term liquid cultures in a dose-dependent fashion with maximal inhibition of 72% at a concentration of retinoic acid of 1 mumol/L. Although no significant effects were observed on granulocyte-macrophage CSF (GM-CSF)--interleukin-3--or stem cell factor (SCF)-induced proliferation, the combinations of G-CSF and each of these cytokines were all inhibited. Moreover, retinol (3 mumol/L) and chylomicron remnant retinyl esters (0.1 mumol/L) in concentrations normally found in human plasma also had inhibitory effects. Single-cell experiments showed that the effects of retinoic acid were directly mediated. Retinoids also significantly inhibited G-CSF-induced colony formation in semisolid medium, with 88% inhibition observed at a concentration of retinoic acid of 1 mumol/L. However, we did not observe any effects of retinoic acid on G-CSF-induced differentiation as assessed by morphology and flowcytometry. Similar to previous findings using total bone marrow mononuclear cells, we observed a stimulation of GM-CSF-induced colony formation after 14 days. We also observed a stimulatory effect of low doses of retinoic acid (30 nmol/L) on blast-cell colony formation on stromal cell layers. Taken together, the data indicate that vitamin A present in human plasma has inhibitory as well as stimulatory effects on myelopoiesis.

Adult↗
PubMed1994

Role of the 75-kDa tumor necrosis factor receptor: inhibition of early hematopoiesis.

Biological effects of tumor necrosis factor alpha (TNF-alpha) are mediated through two cell surface receptors, the 55-kDa TNF receptor and the 75-kDa TNF receptor. The present study investigated the relative roles of the two TNF receptors in normal hematopoiesis. Using agonists (antibodies) specific for the 55- and 75-kDa TNF receptors, we demonstrate differential roles of the two TNF receptors in hematopoiesis in that only the 55-kDa TNF receptor mediates antiproliferative effects of TNF-alpha on mature Lin- hematopoietic progenitor cells responding to granulocyte colony-stimulating factor or interleukin 3 alone. In contrast, the 75-kDa TNF receptor is essential in mediating inhibition of primitive Lin-Sca-1+ high-proliferative-potential colony-forming cells and inhibition of the total number of proliferative clones of individually cultured Lin-Sca-1+Rh123lo and Lin-Sca-1+Rh123hi cells.

Animals↗
PubMed1994

Functional differences between CD38- and DR- subfractions of CD34+ bone marrow cells.

Several studies have previously demonstrated enrichment in primitive progenitor cells in subfractions of CD34+ bone marrow (BM) cells not expressing CD38 or HLA-DR (DR) antigens. However, no studies have directly compared these two cell populations with regard to their content of primitive and more committed progenitor cells. Flow cytometric analysis of immunomagnetic isolated CD34+ cells demonstrated little overlap between CD34+CD38- and CD34+DR- progenitor subpopulations in that only 12% to 14% of total CD34+DR- and CD34+CD38- cells were double negative (CD34+CD38-DR-). Although the number of committed myeloid progenitor cells (colony-forming units granulocyte-macrophage) was reduced in both subpopulations, only CD34+CD38- cells were significantly depleted in committed erythroid progenitor cells (burst-forming units-erythroid). In single-cell assay, CD34+CD38- cells showed consistently poorer response to single as opposed to multiple hematopoietic growth factors as compared with unfractionated CD34+ cells, indicating that the CD34+CD38- subset is relatively enriched in primitive hematopoietic progenitor cells. Furthermore, CD34+CD38- and CD34+DR- cells, respectively, formed 3.2-fold and 1.6-fold more high proliferative potential colony-forming cell (HPP-CFC) colonies than did unfractionated CD34+ cells. Finally, CD34+CD38-DR- cells were depleted in HPP-CFCs as compared with CD34+CD38+DR+ cells. The results of the present study suggest that both the CD38- and DR- subfractions of CD34+ bone marrow cells are enriched in primitive hematopoietic progenitor cells, with the CD34+CD38- subpopulation being more highly enriched than CD34+DR- cells.

ADP-ribosyl Cyclase↗
PubMed1994

Bifunctional effects of tumor necrosis factor alpha (TNF alpha) on the growth of mature and primitive human hematopoietic progenitor cells: involvement of p55 and p75 TNF receptors.

Tumor necrosis factor alpha (TNF alpha) has previously been reported to have both inhibitory and stimulatory effects on hematopoietic progenitor cells. Specifically, TNF alpha has been proposed to stimulate early hematopoiesis in humans. In the present study we show that TNF alpha, in a dose-dependent fashion, can potently inhibit the growth of primitive high proliferative potential colony-forming cells (HPP-CFCs) stimulated by multiple cytokine combinations. Using agonistic antibodies to the p55 and p75 TNF receptors or TNF alpha mutants specific for either of the two TNF receptors, we show that both receptors can mediate this inhibition. In contrast, the potent stimulation of interleukin-3 (IL-3) plus granulocyte-macrophage colony-stimulating factor (GM-CSF) induced HPP-CFC colony formation observed at low concentrations of TNF alpha (2 ng/mL) was only a p55-mediated event. Moreover, the stimulatory effects of TNF alpha on GM-CSF or IL-3-induced colony formation, as well as the inhibition of G-CSF-induced colony growth, were also exclusively signaled through the p55 TNF receptor. Taken together, our results suggest that the inhibitory effects of TNF alpha on primitive bone marrow progenitor cells are mediated through both p55 and p75 TNF receptors, whereas the p55 receptor exclusively mediates the bidirectional effects on more mature, single factor-responsive bone marrow progenitor cells as well as stimulation of IL-3 plus GM-CSF-induced HPP-CFC colony growth.

Adult↗
PubMed1994

Tumor necrosis factor-alpha inhibits stem cell factor-induced proliferation of human bone marrow progenitor cells in vitro. Role of p55 and p75 tumor necrosis factor receptors.

Stem cell factor (SCF), a key regulator of hematopoiesis, potently synergizes with a number of hematopoietic growth factors. However, little is known about growth factors capable of inhibiting the actions of SCF. TNF-alpha has been shown to act as a bidirectional regulator of myeloid cell proliferation and differentiation. This study was designed to examine interactions between TNF-alpha and SCF. Here, we demonstrate that TNF-alpha potently and directly inhibits SCF-stimulated proliferation of CD34+ hematopoietic progenitor cells. Furthermore, TNF-alpha blocked all colony formation stimulated by SCF in combination with granulocyte colony-stimulating factor (CSF) or CSF-1. The synergistic effect of SCF observed in combination with GM-CSF or IL-3 was also inhibited by TNF-alpha, resulting in colony numbers similar to those obtained in the absence of SCF. These effects of TNF-alpha were mediated through the p55 TNF receptor, whereas little or no inhibition was signaled through the p75 TNF receptor. Finally, TNF-alpha downregulated c-kit cell-surface expression on CD34+ bone marrow cells, and this was predominantly a p55 TNF receptor-mediated event as well.

Adult↗
PubMed1994

A simple subtraction method for the isolation of cell-specific genes using magnetic monodisperse polymer particles.

In this study we present a simple subtraction method for the isolation of cell-type-specific genes using magnetic beads. Biotinylated first-strand cDNA is generated from one cell type and immobilized onto magnetic streptavidin beads. Poly A+ RNA, isolated from a different cell type by use of oligo-dT beads, is then hybridized to the immobilized cDNA. Beads with hybridized mRNA are subsequently removed from the solution by attraction to a magnet. The cell-specific mRNA, left in solution, is finally converted to a radiolabeled cDNA probe in order to screen cDNA libraries. In this study, we present an example of a successful subtraction strategy involving three cell types: the pre-B-cell line Reh; 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated Burkitt's lymphoma line Daudi; and TPA-stimulated T lymphocytes. This strategy was chosen due to our interest in gene products known to be expressed in TPA-stimulated B and T lymphocytes, but not in Reh cells. Several previously unknown genes were identified.

B-Lymphocytes↗
PubMed1993

Cytotoxic lymphocyte maturation factor (interleukin 12) is a synergistic growth factor for hematopoietic stem cells.

The recently cloned cytotoxic lymphocyte maturation factor (interleukin 12 [IL-12]) has been described as a growth factor for mature lymphocytes. The present study investigated whether purified recombinant murine IL-12 (rMuIL-12) also could affect the proliferation of primitive bone marrow progenitor cells. Using a population of Lin-Sca-1+ murine bone marrow stem cells, we now demonstrate that IL-12 is a potent synergistic factor for primitive hematopoietic stem cells. The synergy of IL-12 was observed in single-cell cloning assays, demonstrating that its effects are directly mediated. Specifically, IL-12 enhanced stem cell factor-induced myelopoiesis of Lin-Sca-1+ cells sevenfold, and synergized with colony-stimulating factors (CSFs) to induce proliferation of Lin-Sca-1+ stem cells. IL-12 increased the number of responding progenitor cells as well as the size of the colonies formed. IL-12 also increased colony formation of high proliferative potential colony-forming cells with multiple CSF combinations. The effects of IL-12 were concentration dependent with a 50% effective dose of 2-20 and 20-200 ng/ml, resulting in maximum stimulation. Furthermore, a neutralizing anti-IL-12 antibody blocked the synergistic effects of rMuIL-12. In addition, IL-12 was found to have synergistic effects on more committed bone marrow progenitors as well. Our results therefore suggest that in addition to being a potent lymphopoietic stimulator, IL-12 is a regulator of the growth of hematopoietic stem cells and their myeloid progeny.

Animals↗
PubMed1993

Expression of CD18 (integrin beta 2 chain) correlates with prognosis in malignant B cell lymphomas.

Several studies have shown that cell cycle related parameters including DNA synthesis and activation antigen expression can predict patient survival in lymphoma patients. In this study of 69 malignant B cell lymphomas we have examined the cell surface expression of several cell interaction and activation molecules by flow cytometry. Expression of CD18 (integrin beta 2 chain) was found to correlate strongly with patient survival (median follow up 50 months) even when adjusting for other important prognostic factors (P = 0.0001). The percentage of cells positive for CDw75 proved important both as a single parameter and in the multivariate analysis. Histology, classified as low versus high grade malignancy, bulky versus not bulky disease and high versus low thymidine incorporation, was also found to correlate with prognosis in this study.

Antigens, CD↗
PubMed1992

Vitamin A is a key regulator for cell growth, cytokine production, and differentiation in normal B cells.

In the present paper we demonstrate that retinol-retinol-binding protein and chylomicron remnant retinyl esters in concentrations normally found in human plasma inhibit growth of normal human B lymphocytes. Physiological concentrations of retinoic acid (about 30 nM) were less active than physiological concentrations of retinol (about 3 microM). Pharmacological concentrations of retinol and retinoic acid were more active than the concentrations normally found in plasma. Retinol (3 microM) inhibited anti-IgM-mediated DNA synthesis as measured by [3H]thymidine uptake at 72 h by 78%. Furthermore, we found that the cells were blocked in the mid-G1 phase of the cell cycle. Thus, neither MYC up-regulation measured at 3 h nor the expression of the early activation antigen 4F2 was reduced by retinol, whereas the late activation markers (transferrin receptor expression and actinomycin D staining at 48 h of stimulation) were markedly inhibited. Retinol reduced the interleukin 6 production induced by anti-IgM and interleukin 4 after 48 h, whereas the induction of interleukin 6 and tumor necrosis factor by O-tetradecanoylphorbol-13-acetate and ionomycin was less affected. We also noted that the retinoids reduced the formation of plaque-forming cells (i.e. Ig synthesis). These data imply that vitamin A present in human plasma is a normal modulator of B cell function.

B-Lymphocytes↗
PubMed1992

Differential chromatin structure-dependent binding of 7-aminoactinomycin D in normal and malignant bone marrow hematopoietic cells.

Chromatin structure-dependent binding of the DNA-specific dye 7-aminoactinomycin D (7-AMD) in leukemic and normal cells in bone marrow aspirates from childhood acute leukemia patients and patients without bone marrow neoplasia was assessed by multiparameter flow cytometry. Simultaneous staining with fluorescein isothiocyanate-labeled antibodies was needed in many cases for determination of the immunophenotype of the cells that exhibited differential binding of 7-AMD. 7-AMD binding was enhanced in normal (4 patients) and malignant (8 patients) myeloid cells, and was generally low in normal and leukemic lymphocytes and normoblasts. Four of 18 aspirates from 16 patients with acute lymphoblastic leukemia contained neoplastic cells with increased 7-AMD binding capability. The 7-AMD binding of the leukemic cells was not correlated to S-phase fraction (P = 0.07), but was significantly correlated to cell size as measured by forward angle light scattering (r = 0.49, P = 0.007). Patients with tumor cells exhibiting low 7-AMD binding at last aspirate survived significantly longer than the patients with leukemic cells binding high amounts of 7-AMD (P = 0.03). Neither cell size, S-phase fraction, nor ploidy status predicted patient survival in this small scale study.

Antigens, CD↗
PubMed1992

A new method for detachment of Dynabeads from positively selected B lymphocytes.

This paper describes a method for the detachment of immunomagnetic beads from positively selected human B lymphocytes. After rosetting of B cells using anti-CD19 coated magnetic beads (Dynabeads M-450 Pan B, Dynal), the Dynabeads were rapidly detached (efficiency 80%) from the cells using goat anti-mouse-Fab antiserum (DETACHaBEAD, Dynal) at ambient temperature. Isolated B cells did not show significant differences in the expression of a number of B cell antigens when compared to B cells stained in fresh whole blood. In contrast, positively selected B cells that had detached from the beads following overnight incubation, demonstrated a significantly reduced expression of certain of the antigens examined (CD19, CD20 and CD23). It was further demonstrated that neither anti-CD19 nor anti-Fab resided on the surface of the cells after detachment. The cells were still in G0 phase (greater than 90%) at the end of the isolation procedure. Moreover, anti-IgM antibodies stimulated the vast majority of the cells to leave the G0 phase, and to progress through S phase in the presence of growth factors. The cells could also be stimulated to differentiate, further confirming the normal functional capacity of the isolated cells. The method described in this paper can also be used for the detachment of other positively selected cells, such as CD4+ T cells, CD8+ T cells and CD34+ stem cells.

Antigens, CD↗