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Biomedical subjects

W Piacibello

Publications and source records attributed to W Piacibello.

At least 55 records · Page 3Linked to original sources
PubMed1986

Human gamma interferon enhances release from phytohemagglutinin-stimulated T4+ lymphocytes of activities that stimulate colony formation by granulocyte-macrophage, erythroid, and multipotential progenitor cells.

Human gamma interferon (HuIFN gamma) was evaluated for its effects on the release from human peripheral blood T lymphocytes (greater than 98% pure) stimulated by phytohemagglutinin (PHA) of activities that can stimulate granulocyte-macrophage (CFU-GM) colonies and clusters, erythroid (BFU-E) bursts, and mixed (CFU-GEMM) colonies. T lymphocytes did not release these activities in the absence of PHA with or without HuIFN gamma. In the presence of PHA, pure natural HuIFN gamma at concentrations of 0.1 to 100 U/mL significantly enhanced release of these colony-stimulating activities. Although enhanced release of granulocyte-macrophage colony-stimulating activities were noted when T lymphocytes were added to the conditioning medium in the presence of 0.1%, 0.5%, and 1% PHA, enhanced release of burst-promoting and mixed colony activities was seen only in the presence of 0.1% and 0.5% PHA. The enhanced release of colony-stimulating activities was not due to HuIFN gamma-suppression of the release from PHA-stimulated T lymphocytes of suppressor molecules. The enhancing effects of natural HuIFN gamma were neutralized with a monoclonal anti-natural HuIFN gamma, and recombinant HuIFN gamma mimicked the enhancing effects of the natural HuIFN gamma. This enhancing effect was noted only when HuIFN gamma was added with the T lymphocytes and PHA during the first 24 hours of incubation. T lymphocytes were separated into T4+, T8-, T8+, and T4- subsets (greater than 98% pure for the appropriate phenotypes) after incubation with OKT4- and OKT8- monoclonal antibodies and sorting on a fluorescence-activated cell sorter (FACS). All types of colony-stimulating activities were released from each population after stimulation with PHA, but enhanced release of these activities in the presence of HuIFN gamma was only detected with the T4+ or T8- subsets of lymphocytes. It cannot be concluded from these studies whether HuIFN gamma is enhancing the release of one or several types of colony-stimulating activities, but these studies suggest a role for HuIFN gamma and T4+ lymphocyte subsets in the regulation in vitro of the release of colony-stimulating activities.

Colony-Forming Units Assay↗
PubMed1986

Expression of HLA class II (DR, DQ) determinants by normal and chronic myeloid leukemia granulocyte/monocyte progenitors.

It has been suggested that the expression of certain HLA class II antigens stemming from three distinct loci (DR, DP, and DQ) is important not only in the regulation of the immune response but also on the response of hemopoietic precursors to factors inhibiting myelopoiesis. Changes in the expression of DR antigens may be involved in the pathogenesis of altered cell proliferation in chronic myeloid leukemia, since they result in decreased sensitivity of the colony forming units, granulocyte-macrophage to prostaglandin E and acidic isoferritins. In studies using monoclonal antibodies against monomorphic DR or DQ determinants, in a complement-dependent cytotoxic assay, it was found that nearly all normal and chronic myeloid leukemia bone marrow colony forming units, granulocyte-macrophage express DR antigens. The dose response curve was similar for both normal and leukemic precursors. Leukemic peripheral blood precursors were more sensitive than were normal peripheral blood precursors. Normal colony forming units, granulocyte-macrophage did not express DQ antigens, whereas these were expressed in varying quantities by leukemic cells. This study shows that, in the patients we studied, leukemic cells express DR antigens in amounts comparable to normal. In addition, varying amounts of DQ antigens may be observed on leukemic but not on normal progenitors, perhaps as a consequence of an increase in the number of antigens also expressed by normal cells, though in an amount below the detection threshold of cytotoxicity techniques.

Animals↗
PubMed1986

Purified human transferrin and "transferrin" released from sorted T8+ lymphocytes suppress release of granulocyte-macrophage colony-stimulating factors from sorted T4+ lymphocytes stimulated by phytohemagglutinin.

Nonadherent, low-density E-rosette-positive human peripheral blood cells were separated into T4+ and T8+ lymphocytes by immuno-fluorescence-activated cell sorting (FACS) with monoclonal antibodies OKT4 and OKT8. Both T4+ and T8+ lymphocytes released granulocyte-macrophage colony-stimulating factors (GM-CSF) in response to phytohemagglutinin (PHA). Purified iron-saturated human transferrin (TF) suppressed release of GM-CSF only from the T4+ subset of lymphocytes. A TF-type inhibitory activity was released from the T8+ subset of lymphocytes alone, and this inhibitory activity, as well as that in purified TF, was inactivated by preincubation with antihuman TF monoclonal antibody (HT/1). These studies suggest that, at least in vitro, subsets of T-lymphocytes and TF may be involved in the regulation of myelopoiesis.

Cell Separation↗
PubMed1986

Effect of acidic and basic isoferritins on in vitro growth of human granulocyte-monocyte progenitors.

Acidic isoferritins have been previously found to be highly potent inhibitors of hematopoietic progenitors at concentrations of 10(-16) to 10(-18) mol/L, and it has been suggested that acidic isoferritin inhibitory activity plays a role in the regulation of normal hematopoiesis and also in the pathogenesis of leukemia. To characterize the ferritin species that affect the in vitro growth of human colony-forming unit-granulocyte-macrophage (CFU-GM), we tested different preparations of basic (L-subunit-rich) and acidic (H-subunit-rich) isoferritins. Three preparations of human liver (basic) ferritin did not show any effects on CFU-GM growth at concentrations up to 10(-9) mol/L, irrespective of the degree of glycosylation. Acidic isoferritins were purified both from HeLa cells and human heart. HeLa cell ferritin did not affect in vitro colony formation. One of two preparations of human heart ferritin, containing 5% glycosylated ferritin, showed a mean inhibition of 26% +/- 8% of the control at 10(-9) mol/L (P less than .02), whereas the other preparation, which contained no glycosylated ferritin, did not show any effect of CFU-GM growth. A preparation enriched for glycosylated acidic isoferritins from human heart was found to produce a mean inhibition of 32% +/- 11% of the control at 10(-9) mol/L (P less than .01), whereas another one was ineffective. A significant part of the inhibitory activity was removed by preincubation with the monoclonal antibody 2A4 directed against human heart ferritin. The present findings indicate that basic isoferritins, ie, the predominant ferritin type in human blood, have no effect on the growth of human CFU-GM, and this is in keeping with indirect clinical evidence. Inhibition of colony formation may be obtained by some preparations of acidic isoferritins that are rich in H subunits and bind to concanavalin A. The mechanism(s) responsible for this are not clear, but the effective concentrations are higher than those found in human blood both under normal conditions and in leukemia. At present, the physiologic significance of the observed inhibitory activity is uncertain.

Ferritins↗
PubMed1985

H2 receptor antagonists and human granulopoiesis.

The effect of 2 H2 receptor antagonists (ranitidine and cimetidine) on the in vitro growth of human granulomonopoietic precursors (CFU-GM) was studied. Ranitidine, although having an anti H2 receptor activity much greater than that of cimetidine, displays the same toxicity for CFU-GM.

Cimetidine↗
PubMed1985

In-vitro effect of retinoic acid on normal and chronic myeloid leukemia granulopoiesis.

The effect of increasing concentrations of retinoic acid (RA) on the in-vitro proliferation of normal and chronic myeloid leukemia (CML) granulo-monocyte precursors (CFU-GM) was studied. 10(-7)M RA added to semisolid cultures stimulated the growth of day 14 but not of day 7 normal CFU-GM, whereas in CML the growth of both populations was either unchanged or inhibited. Five-day and 10-day preincubation of normal bone marrow cells with RA augmented the number of day 14 CFU-GM (by up to 187% with 10(-6) M RA), whereas there was a marked decrease when CML cells were used. Total cellularity was not much affected, though a slight increase in liquid normal bone marrow cultures and a slight fall in CML cultures could be detected. These data point to a difference in the response to RA of normal and CML precursors. They may offer of preclinical basis for its employment to delay the blastic progression of CML.

Cell Differentiation↗
PubMed1985

Release of granulocyte-macrophage colony stimulating factors from major histocompatibility complex class II antigen-positive monocytes is enhanced by human gamma interferon.

Human gamma interferon (HuIFN gamma) was assessed for its capacity to enhance release of granulocyte-macrophage colony stimulating factors (GM-CSF) from human peripheral blood monocytes. Natural HuIFN gamma (2 X 10(7) NIH reference units per milligram) at concentrations as low as 0.01 U/mL to 10 U/mL reproducibly enhanced release of GM-CSF. This enhancement was detected when T lymphocytes were depleted from monocyte preparations and when T lymphocytes and monocytes were depleted from populations of human bone marrow cells stimulated by monocyte-conditioned media to form colonies and clusters. T lymphocytes alone or in the presence of HuIFN gamma did not release GM-CSF. The enhancing activity of HuIFN gamma was removed by preincubating HuIFN gamma with neutralizing concentrations of monoclonal anti-HuIFN gamma, and recombinant HuIFN gamma mimicked the effects of natural HuIFN gamma, suggesting that the effects were due to HuIFN gamma itself. HuIFN gamma suppression of the release of inhibitory activity from monocytes was ruled out as a reason for the noted enhancing activity of HuIFN gamma. The enhancing activity of HuIFN gamma was confined to the MHC class II antigen-positive population of monocytes. Removal of these cells with monoclonal antibody plus complement (C') ablated the enhancing activity, high concentrations of certain monoclonal antibodies in the absence of C' blocked the enhancing activity and, when monocytes were sorted into MHC class II antigen-positive and -negative cells by fluorescence-activated cell sorting, it was only the positive cell fraction that responded to the enhancing activity of HuIFN gamma.

Cells, Cultured↗
PubMed1984

Differences in the in vitro growth pattern of fresh and cryopreserved granulo-monopoietic precursors.

A study of the in vitro growth model of human granulo-monopoietic precursors (CFU-GM) before and after cryopreservation using both leukocyte feeder layers and GCT conditioned medium as the source of colony stimulating activity (CSA) is reported. The number of colonies produced with fresh cells was linearly related to the amount of marrow seeded with both CSA sources, whereas after cryopreservation this was true with feeder layers, and with GCT only at relatively high cell concentrations. This might indicate the production of granulopoietic stimulators on the part of a second population that is at least partly resistant to freezing. It seems more likely, however, that these results depend mainly on a sublethal damage to CFU-GM induced by freezing, thus making the cells hyporesponsive to some forms of CSA, such as those contained in GCT conditioned medium.

Cell Division↗
PubMed1984

Retinoic acid enhances the growth of only one subpopulation of granulomonocyte precursors.

The effect of various concentrations of retinoic acid on the growth of committed granulomonopoietic precursors (CFU-GM) was studied on semisolid agar cultures. Retinoic acid increased the growth of day 14 CFU-GM but had no significant effect on day 7 CFU-GM. Since the latter are believed to represent the progeny of day 14 CFU-GM it is suggested that the effect of retinoic acid is confined to the early stages of granulomonocytic differentiation.

Bone Marrow Cells↗
PubMed1984

An in vitro study of basophil production in chronic myeloproliferative disorders.

An examination was carried out of certain parameters of basophil production in semisolid agar cultures by granulomonocyte precursors (CFU-C) from normal subjects and from patients with chronic myeloproliferative disorders. Basophils were rare in the first four days of culture, after which their number increased gradually to reach a plateau on about the 12th day. Pure basophil colonies were frequent only in cultures from a patient with marked basophilia. In the other cases the colonies also included other cells of the granulomonocyte pathway. There was a linear correlation between basophilia in vivo and basophil production in vitro. The latter, however, was influenced by the type of colony-stimulating activity (CSA) used. Different CSA sources, inducing the production of a comparable number of colonies, did not stimulate basophilic differentiation in the same way. Serum from patients with chronic myelocytic leukemia and varying degrees of basophilia did not have a significant effect on autologous in vitro basophilopoiesis, nor did it increase that of normal CFU-C.

Basophils↗
PubMed1984

Functional activities of acidic isoferritins and lactoferrin in vitro and in vivo.

The functional activities of acidic isoferritins (AIF) and lactoferin (LF) were evaluated. The inhibitory activity of AIF (AIFIA) was inactivated by preincubation with a monoclonal antibody (2A4) against AIF, but AIFIA was not inactivated by another monoclonal antibody against AIF (1C5), by a monoclonal antibody (3A5) against basic isoferritins, or by a heteroantiserum (LFT) against basic isoferritins. Monoclonal 2A4 also inactivated the inhibitory activity against colony formation by granulocyte-macrophage (CFU-GM) progenitor cells that was constitutively released by human monocytes or induced by human monocytes in the presence of OKT4+ lymphocytes. In addition to OKT4+ lymphocytes, the release of AIFIA from human monocytes was modulated by iron-saturated human LF and OKT8+ lymphocytes, both of which suppressed the release of AIFIA. Evidence for the physiologic relevance of AIF as a regulator of myelopoiesis was presented, in that human AIF suppressed the numbers of CFU-GM, BFU-E, and CFU-GEMM per femur and the cycling status of these cells in mice recovering from a sublethal dosage of Cytoxan. Abnormalities in LF and AIF interactions were found with cells from a pediatric patient with neutrophilia of unknown etiology that were consistent with the disease manifestations of neutrophilia. Polymorphonuclear neutrophils (PMN) from the patient contained low levels (1%-10% of control) of immunologically reactive LF and the LF found was ineffective as a suppressor molecule for the release of GM-CSF from normal mononuclear blood cells. In addition, the patient's GM-CSF releasing mononuclear blood cells were insensitive to the suppressive effects of purified LF, and colony formation by the patient's CFU-GM, but not BFU-E or CFU-GEMM, were insensitive to the suppressive effects of purified AIF. When the activity of purified AIF was assessed against mouse bone marrow cells under serum-free conditions, it was apparent that serum was not needed for the suppressive activity of AIF and that in some cases, serum actually masked the effects of AIF. Human monoblast cell line U937 was found to be a good model in vitro for the actions of LF and AIF; U937 cells induced for Ia-antigens by human gamma interferon were separated into populations of Ia-antigen+ and Ia-antigen- cells by fluorescence activated cell sorting (FACS), and LF and AIF suppressed colony formation only by the Ia-antigen+ U937 cells. A comparative analysis of bovine and human LF against release of GM-CSF from human mononuclear cells demonstrated that both were active in their iron-saturated form.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Responsiveness to prostaglandin E1 of different subtypes of normal and pathological committed granulomonopoietic precursors.

The influence of prostaglandin E1 (PGE1) on colonies produced by different subtypes of committed granulomacrophagic precursors (CFU-GM) was studied. Even though they represent a more immature class of precursors than day 7 CFU-GM, day 14 CFU-GM have the same sensitivity to PGE1: their growth is significantly inhibited by low PGE1 concentrations (10(-10) M or higher). Macrophagic colony formation is most sensitive to PGE1. Pure granulocytic colonies are relatively resistant and significantly inhibited by high concentrations only. Mixed granulomacrophagic colonies display an intermediate degree of sensitivity. Both day 7 and day 14 CFU-GM from chronic myeloid leukemia and idiopathic myelofibrosis patients are significantly less sensitive than normal CFU-GM. This insensitivity is not dependent on a lack of production of macrophagic colonies, since these may even be present in a higher than normal frequency.

Alprostadil↗
PubMed1983

Biosynthesis and release of platelet-activating factor from human monocytes.

The aim of the present study was to investigate the pathways of platelet-activating factor (PAF) production and release from human monocytes. For this purpose, both phagocytic stimuli and stimuli induced by soluble agents were used. The phagocytic stimuli exerted their effect in a receptor-specific mechanism related to surface Fc, C3b and C3d receptors. Stimuli induced by soluble agents, such as A23187 and pH 10.6, which do not require interaction with specific receptors, were also effective in inducing PAF release. In contrast, C5a, a soluble agent which induces a receptor-mediated release of PAF from neutrophils, failed to induce PAF release from monocytes. PAF release from monocytes could be dissociated from phagocytosis and from release of lysozyme. The PAF release required the presence of extracellular cations, the activation of membrane esterase and phospholipase A2 and the integrity of the microfilament system. Moreover, PAF release was modulated by lipoxygenase and intracellular cAMP levels. The relevance of an acetylation process in the biosynthesis of PAF was suggested by the increase of PAF yields in the presence of sodium acetate and by the incorporation of 14C-sodium acetate into molecules of active PAF.

Acetates↗
PubMed1983

The release of platelet-activating factor from human endothelial cells in culture.

The release of platelet-activating factor (PAF) from stimulated human endothelial cells (HEC) cultured from normal term, umbilical cord veins is described. HEC in primary cultures released PAF after challenge with A23187, rabbit anti-human factor VIII (RaHu/FVIII), angiotensin II, and vasopressin. HEC subcultures maintained the ability to release PAF in the presence of A23187 and RaHu/FVIII, whereas the release of PAF in response to angiotensin II and vasopressin was not constant and was reduced. Control cultured, smooth muscle cells derived from umbilical cord veins, previously depleted of endothelial cells, did not release PAF under the above-mentioned stimulation. Plastic-adherent or cultured monocytes released PAF with A23187, but not with RaHu/FVIII, angiotensin II, and vasopressin. The release of PAF from HEC in primary cultures required the presence of extracellular cations and the activation of membrane phospholipase A2. PAF release induced by A23187, RaHu/FVIII, angiotensin II, and vasopressin was unaffected by indomethacin, an inhibitor of cyclooxygenase, which, however, favored the release of PAF from HEC stimulated with thrombin, a stimulus that did not affect HEC in the absence of indomethacin. PGI2 inhibited PAF release from stimulated HEC. The relevance of an acetylation process in the biosynthesis of PAF and HEC was supported by the following evidence: 1) the increase in PAF yield in the presence of sodium acetate and, particularly, of acetyl-CoA; 2) the incorporation of [14C]acetate into PAF molecules; 3) the loss of radioactivity and of biologic activity after treatment with phospholipase A2. These results indicate that HEC in culture are able to release PAF and that metabolic pathways similar to those described for leukocytes are involved.

Angiotensin II↗