Biomedical subjects

H E Broxmeyer

Publications and source records attributed to H E Broxmeyer.

At least 325 records · Page 18Linked to original sources

PubMed1987

Comparative effects in vivo of recombinant murine interleukin 3, natural murine colony-stimulating factor-1, and recombinant murine granulocyte-macrophage colony-stimulating factor on myelopoiesis in mice.

Purified murine colony-stimulating factors (CSF) recombinant interleukin 3 (IL-3), natural CSF-1, and recombinant granulocyte-macrophage (GM) CSF were assessed in vivo for their effects on BDF1 mouse bone marrow and spleen granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells in untreated mice and in mice pretreated with purified iron-saturated human lactoferrin (LF). The CSF and LF preparations did not contain detectable endotoxin (less than 0.1 ng). Mice pretreated with LF were more sensitive to the effects of CSF. In mice pretreated with LF, 2,000 U IL-3 or 20,000 U CSF-1 significantly enhanced the cycling status and absolute numbers of all progenitors, whereas 20,000 U GM-CSF significantly increased the cycling status of CFU-GM and CFU-GEMM, but had no effect on cycling of BFU-E or on numbers of any of the progenitors. The effects of CSF in mice pretreated with LF were not mimicked by 0.1-100 ng E. coli lipopolysaccharide.

Animals↗

PubMed1987

Interactions between purified murine colony-stimulating factors (natural CSF-1, recombinant GM-CSF, and recombinant IL-3) on the in vitro proliferation of purified murine granulocyte-macrophage progenitor cells.

Purified preparations of natural CSF-1 (nCSF-1), recombinant GM-CSF (rGM-CSF), and recombinant IL-3 (rIL-3), alone and in combination, were investigated for their proliferative effects on highly enriched murine granulocyte-macrophage progenitor cells (CFU-GM). These CFU-GM had cloning efficiencies of 62%-95% in the presence of 10% (vol/vol) pokeweed mitogen-stimulated spleen cell-conditioned medium, and contained few, if any (less than or equal to 3%), contaminating morphologically recognizable monocytes or lymphocytes. The combination of low concentrations of nCSF-1 plus rIL-3, or nCSF-1 plus rGM-CSF, increased colony number greater than additively compared to the sum of colony formation with each factor alone, whereas total aggregate (colony plus cluster) number increased additively. At plateau concentrations, the previous CSF combinations increased colony number additively. Colony size was increased when nCSF-1 plus either rGM-CSF or rIL-3 were added simultaneously at either low or plateau concentrations, when compared to the size of colonies with any of the CSFs alone. Addition of rGM-CSF plus rIL-3 demonstrated no cooperative proliferative effect on either colony number or size. It is likely that these effects are mediated at the progenitor cell level and do not require accessory cell participation.

Animals↗

PubMed1987

Effects of purified iron-saturated human lactoferrin on spleen morphology in mice infected with Friend virus complex.

The present report describes effects of lactoferrin treatment on the development of erythroleukemia in the spleen of mice infected with Friend virus complex (FVC). Lactoferrin (LF) treatment was carried out in mice for up to 2 weeks at a total dose of 200 micrograms per mouse. The treatment was started at Days 7 and 14 prior to viral infection and Days 0, 1, 3, 7, and 11 after viral infection. Spleens were analyzed 14 days after viral infection. In mice whose treatment was initiated at Days 0 and 1, few leukemic cells were present in the spleen. Most of them appeared in clumps in the red pulp. No leukemic cells were seen in the white pulp. The white pulp was greatly enlarged. In mice whose treatment was initiated at Day 3, leukemic cells began to spread out in the red pulp and encroached upon the white pulp. The white pulp was enlarged and clearly visible. In mice whose treatment was initiated at Days 7 and 11, many leukemic cells were present in the red pulp. The white pulp was infiltrated by leukemic cells and became less discernible. The morphologic features of the spleen in mice whose treatment was initiated at Day 7 or 14 prior to viral infection were similar to those of untreated groups. Leukemic cells not only filled most of the cordal space in the red pulp but also invaded the white pulp. Many leukemic cells were seen in venous sinuses. When infected mice responded to LF treatment, the general architecture of the red pulp remained intact and the white pulp was enlarged but not infiltrated by leukemic cells.

Animals↗

PubMed1987

Regulation of early human hematopoietic (BFU-E and CFU-GEMM) progenitor cells in vitro by interleukin 1-induced fibroblast-conditioned medium.

Stimulators of human erythroid burst-forming units (BFU-E) and multipotential colony-forming cells (CFU-GEMM) can be produced by a number of different cell types. A product of human peripheral blood monocytes, interleukin 1 (IL-1), was evaluated for its ability to stimulate fibroblast cultures to produce stimulators of human bone marrow BFU-E and CFU-GEMM colony formation. BFU-E and CFU-GEMM colony formation was evaluated using low-density, nonadherent low-density, and T lymphocyte-depleted nonadherent low-density human bone marrow cells cultured in the presence of a source of pure human erythropoietin. Both human monocyte conditioned medium (MCM) and human recombinant IL-1 (hrIL-1) induced fibroblasts to produce stimulators of BFU-E and CFU-GEMM in a dose-dependent fashion with maximal colony formation occurring when fibroblasts were stimulated by 25% MCM or 140 ng/mL ROO6B hrIL-1, or 1.25 to 5 ng/mL ROO6T hrIL-1. Preincubation of MCM and hrIL-1 with an antibody to IL-1 inactivated the ability of MCM and hrIL-1 to induce the release of erythroid and multipotential colony stimulating activity from fibroblasts. These results suggest that monocyte-derived IL-1 is involved in regulating the production of humoral stimulators of early human hematopoietic progenitors.

Bone Marrow Cells↗

PubMed1987

The effects of purified recombinant murine interleukin-3 and/or purified natural murine CSF-1 in vivo on the proliferation of murine high- and low-proliferative potential colony-forming cells: demonstration of in vivo synergism.

Purified natural murine L cell (macrophage) colony-stimulating factor (nCSF-1) and purified recombinant murine interleukin-3 (rIL-3) were administered to normal or lactoferrin-pretreated mice 20 to 24 hours before sacrifice. rIL-3 and nCSF-1 administered separately increased the percentage of macrophage high-proliferative potential colony-forming cells (HPP-CFC) and low-proliferative potential colony-forming cells (LPP-CFC) in active cell cycle. Endotoxin was not detected in the samples of nCSF-1 or rIL-3 with the Limulus lysate test, and the in vitro and in vivo hematopoietic stimulatory effects of both molecules were abolished or markedly reduced by 30 minutes' treatment at 100 degrees C, which demonstrates that the effects noted in vivo were not due to endotoxin. Combinations of low concentrations of rIL-3 and nCSF-1, which by themselves were inactive, increased the percentage of HPP-CFC and LPP-CFC in active cell cycle in a synergistic fashion. No significant change in the number of HPP-CFC or LPP-CFC per femur or femoral nucleated cellularity was observed. Thus, rIL-3 and nCSF-1 can synergize to effect the proliferation of the same cell populations in vivo.

Animals↗

PubMed1987

Prostaglandin E acts at two levels to enhance colony formation in vitro by erythroid (BFU-E) progenitor cells.

The prostaglandin E (PGE) enhancement of erythroid colony formation by human bone marrow erythroid progenitor cells (BFU-E) is mediated by a T8+ subset of lymphocytes. Medium was conditioned by bone marrow and blood T-lymphocytes and T-lymphocyte subsets (T8+, T8-, T4+, and T4- cells) in the absence or presence of PGE1 in order to determine if the cells could release a cell-free source of erythroid colony enhancing activity and what the conditions for this release would be. The T-lymphocyte conditioned medium was assayed for its effects on erythroid colony formation by nonadherent low-density T-lymphocyte depleted (NALT-) bone marrow cells plated in the presence of erythropoietin, hemin, phytohemagglutinin-stimulated leukocyte conditioned medium, or medium conditioned by 5637 cells, in the absence or presence of PGE1 and in the presence or absence of serum. PGE1 induced the release of an erythroid colony enhancing activity from the T8+ and T4-, but not from the T8- and T4+ subsets of lymphocytes, but this cell-free source of activity was only apparent if it was tested for colony formation in the presence of added PGE1. The release and action of the PGE1 induced T-lymphocyte erythroid enhancing activity did not require the presence of serum. Erythroid colony formation by NALT- bone marrow cells was not enhanced by PGE1 alone, by medium conditioned by T-lymphocytes in the absence of PGE1, or by PGE1 plus medium conditioned by T-lymphocytes in the absence of PGE1. The results suggest that the PGE1 enhancement of erythroid colony formation occurs by an apparently synergistic action on non-T-lymphocytes by PGE1 itself and by a factor or factors released from T8+ lymphocytes in response to PGE1.

Alprostadil↗

PubMed1987

The opposing actions in vivo on murine myelopoiesis of purified preparations of lactoferrin and the colony stimulating factors.

The actions of purified iron-saturated human lactoferrin (LF), purified preparations of human MiaPaCa colony stimulating factor-1 (CSF-1), and recombinant murine interleukin-3 (IL-3) were evaluated in vivo in mice. Studies in vitro were compared at lowered (5%), as well as at normal incubator (20%), oxygen (O2) tension because of the potentially greater physiologic relevance of in vitro studies performed at lowered O2 tension. The results demonstrate that 1) increased release of granulocyte-macrophage colony stimulating factor (GM-CSF) in vitro from pokeweed mitogen stimulated mouse spleen cells and from human mononuclear blood cells occurred at lowered O2 tension, and that human mononuclear blood leukocytes were more sensitive to the LF-induced suppression of GM-CSF release when cells were cultured at 5%, compared to 20%, O2 tension; 2) LF administered intravenously (IV) to mice pretreated with sublethal intraperitoneal dosages of Cytoxan decreased the cycling status of marrow and spleen granulocyte-macrophage (CFU-GM), erythroid (BFU-E-2 and BFU-E-1) and multipotential (CFU-GEMM) progenitor cells and the absolute numbers of these progenitors; these effects were most noticeable if care was taken to deplete endotoxin from the LF samples prior to testing LF in vivo and if the control medium was endotoxin free; 3) endotoxin-depleted LF decreased the cycling status of marrow and spleen CFU-GM, BFU-E, and CFU-GEMM and the numbers of these progenitors in the marrows of mice previously untreated with Cytoxan; these effects were most apparent when assessment of progenitor cells and their cycling rates were evaluated in vitro at lowered (5%) O2 tension; 4) purified natural human CSF-1 increased the absolute numbers of marrow CFU-GM and the cycling status of marrow CFU-GM and CFU-GEMM in mice pretreated with LF; and 5) purified recombinant murine IL-3 stimulated proliferation of day 8 and day 12 CFU-S (colony forming unit-spleen) in mice not previously treated with Cytoxan. These results substantiate the in vivo myelosuppressive effects of LF on CFU-GM and extend these effects to erythroid and multipotential progenitor cells, provide evidence that human CSF-1 has an in vivo action in mice, and confirm the studies of others showing that IL-3 stimulates the proliferation of CFU-S in vivo.

Animals↗

PubMed1987

Modulation of Friend virus infectivity in vivo by administration of purified preparations of human lactoferrin and recombinant murine interleukin-3 to mice.

Purified iron-saturated human milk lactoferrin (LF) and purified recombinant murine interleukin-3 (IL-3) were assessed in vivo for their effects on replication of spleen focus forming viruses (SFFV) in spleens of DBA/2 mice injected with the polycythemia-inducing strain of the Friend virus complex. LF and IL-3, inoculated 2 hr prior to the administration of the polycythemia-inducing strain of the Friend virus complex, respectively decreased and increased the replication of SFFV in mice as assessed by the spleen focus forming unit assay in primary and secondary DBA/2 mice. Since virus infectivity is associated with the DNA synthetic phase of the cell cycle and it has been shown elsewhere that LF decreases and IL-3 increases the percent of hematopoietic progenitor cells in S-phase in vivo, the results suggest that the opposing actions of LF and IL-3 on replication of SFFV may reflect the actions of these molecules on cycling of the target cells for SFFV.

Animals↗

PubMed1987

The influence in vivo of murine colony-stimulating factor-1 on myeloid progenitor cells in mice recovering from sublethal dosages of cyclophosphamide.

Pure murine colony-stimulating factor-1 (CSF-1) was assessed for its effects in vivo in mice pretreated seven days earlier with a sublethal dosage of cyclophosphamide. The multipotential (CFU-GEMM), erythroid (BFU-E), and granulocyte-macrophage (CFU-GM) progenitor cells in these mice were in a slowly cycling or noncycling state. Intravenous administration of 20,000 units of CSF-1 to these mice stimulated the hematopoietic progenitors into a rapidly cycling state in the marrow and spleen within three hours. Significant increases in absolute numbers of marrow and spleen CFU-GM and spleen BFU-E and CFU-GEMM were also detected. No endotoxin was detected in the CSF-1 preparation by Limulus lysate assay, and treatment of CSF-1 at 100 degrees C for 20 to 30 minutes completely inactivated the in vitro and in vivo stimulating effects. The effects of CSF-1 were not mimicked by the in vivo administration of 0.1 to 10 ng Escherichia coli lipopolysaccharide. These results suggest that the effects of CSF-1 in vivo were not due to contaminating endotoxin or to a nonspecific protein effect. CSF-1 did not enhance colony formation by BFU-E or stimulate colony formation by CFU-GEMM in vitro, thus suggesting that at least some of the effects of CSF-1 noted in vivo are probably indirect and mediated by accessory cells.

Animals↗

PubMed1987

Purification of murine bone-marrow-derived granulocyte-macrophage colony-forming cells.

Previous attempts to purify progenitor cells that form colonies and clusters of granulocytes and/or macrophages (CFU-GM) from adult murine bone marrow have had limited success because of the paucity of these cells. In the present paper we report studies with a rapid, reproducible method involving pretreatment of mice, three days prior to sacrifice, with 200 mg/kg of Cytoxan (cyclophosphamide), density separation on Ficoll-Hypaque, and counterflow centrifugal elutriation, that yielded highly enriched populations of CFU-GM. The peak CFU-GM-containing fraction (FR-28) eluted at a flow rate of 28 ml/min and contained very little contamination by other in vitro colony-forming cells (BFU-E, CFU-GEMM, CFU-MK). FR-28 contained 0.54% +/- 0.30% (16 experiments) of the unfractionated post-Cytoxan bone marrow nucleated cells and lacked significant contamination by lymphocytes and monocytes. The mean CFU-GM cloning efficiency of FR-28 was 44% +/- 9% in agar (11 experiments) and 75% +/- 10% in agarose (nine experiments). CFU-GM from FR-28 demonstrated linear plating characteristics even at very low cell density (25 cells), and formed colonies and clusters of granulocytes, macrophages, or both in the same proportions as did unfractionated post-Cytoxan or untreated bone marrow. Approximately 10% (assuming a seeding efficiency of 10%) of FR-28 cells were in vivo spleen colony-forming cells (CFU-S) measured at day 12. These results represent the highest degree of purity (up to 94%) of CFU-GM thus far reported and should prove useful in studies of this cell population.

Animals↗

PubMed1986

The influence of T lymphocyte subsets and humoral factors on colony formation by human bone marrow and blood megakaryocyte progenitor cells in vitro.

Cellular and humoral influences of T lymphocytes on human megakaryocyte colony formation in vitro were assessed by using a microagar system. Megakaryocyte colony formation from nonadherent low density T lymphocyte-depleted (NALDT-) bone marrow cells was increased significantly after the addition of aplastic anemia serum (AAS) or purified megakaryocyte colony-stimulating factor (Meg-CSF). The addition of conditioned medium obtained from phytohemagglutinin-stimulated T lymphocytes replaced, at least partially, the requirement for AAS or purified Meg-CSF for the growth of megakaryocyte colonies. The cellular influence of T lymphocytes and T lymphocyte subsets on megakaryocyte colony formation was assessed by removing either T cells from nonadherent peripheral blood mononuclear cells with monoclonal OKT4, OKT8, or OKT3 antibodies plus complement, or by adding back populations of bone marrow or blood T4+ or T8+ lymphocytes, isolated by means of fluorescence-activated cell sorting, respectively, to NALDT--bone marrow or -blood cells. When sorted T cell subpopulations were added to a fixed number of NALDT--bone marrow or -peripheral blood cells in the presence of AAS or Meg-CSF, T4+ cells enhanced megakaryocyte colony formation and T8+ cells decreased it. These studies demonstrate that although the stimulation of megakaryocytic progenitor cells by Meg-CSF may not require the presence of monocytes or T lymphocytes, T4+ lymphocytes enhance and T8+ lymphocytes down-regulate megakaryocyte colony formation induced by Meg-CSF. These observations suggest that the immune system is capable of modulating the proliferative response of human megakaryocytic progenitor cells to Meg-CSF.

Antibody Formation↗

PubMed1986

The suppressive influences of human tumor necrosis factors on bone marrow hematopoietic progenitor cells from normal donors and patients with leukemia: synergism of tumor necrosis factor and interferon-gamma.

The influences of human tumor necrosis factor (TNF) (LuKII), recombinant human TNF-alpha, natural human interferon-gamma (HuIFN-gamma), recombinant HuIFN-gamma, and natural HuIFN-alpha were evaluated alone or in combination for their effects in vitro on colony formation by human bone marrow granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells incubated at 5% CO2 in lowered (5%) O2 tension. TNF (LuKII) and recombinant TNF-alpha caused a similar dose-dependent inhibition of colony formation from CFU-GM, BFU-E, and CFU-GEMM. Day 7 CFU-GM colonies were more sensitive than both day 14 CFU-GM colonies and day 7 CFU-GM clusters to inhibition by TNF. BFU-E colonies and CFU-GEMM colonies were least sensitive to inhibition with TNF. The suppressive effects of TNF (LuKII) and recombinant TNF-alpha were inactivated respectively with hetero-anti-human TNF (LuKII) and monoclonal anti-recombinant human TNF-alpha. The hetero-anti-TNF (LuKII) did not inactivate the suppressive effects of TNF-alpha and the monoclonal anti-recombinant TNF-alpha did not inactivate TNF (LuKII). The suppressive effects of TNF did not appear to be mediated via endogenous T lymphocytes and/or monocytes in the bone marrow preparation, and a pulse exposure of marrow cells with TNF for 60 min resulted in maximal or near maximal inhibition when compared with cells left with TNF for the full culture incubation period. A degree of species specificity was noted in that human TNF were more active against human marrow CFU-GM colonies than against mouse marrow CFU-GM colonies. Samples of bone marrow from patients with non-remission myeloid leukemia were set up in the CFU-GM assay and formed the characteristic abnormal growth pattern of large numbers of small sized clusters. These cluster-forming cells were more sensitive to inhibition by TNF than were the CFU-GM colonies and clusters grown from the bone marrow of normal donors. The sensitivity to TNF of colony formation by CFU-GM of patients with acute myelogenous leukemia in partial or complete remission was comparable with that of normal donors. When combinations of TNF and HuIFN were evaluated together, it was noted that TNF (LuKII) or recombinant TNF synergized with natural or recombinant HuIFN-gamma, but not with HuIFN-alpha, to suppress colony formation of CFU-GM, BFU-E, and CFU-GEMM from bone marrow of normal donors at concentrations that had no suppressive effects when molecules were used alone.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1986

Biomolecule-cell interactions and the regulation of myelopoiesis.

The regulation of myelopoiesis in vivo most likely entails a complex set of interactions between cell-derived biomolecules and their target cells. Much of what we currently know of these interactions has been derived from studies in vitro utilizing techniques for the purification of both the biomolecules and the cells producing and responding to these factors. Stimulating and suppressing influences have been uncovered, and with the cloning and purification of biologically active factors, studies assessing the actions of these molecules in vivo have begun. From studies in vitro it is apparent that many of the purified molecules can have move than one action and that different molecules can collaborate in a synergistic manner to enhance or suppress functional endpoints.

Animals↗

PubMed1986

The effects in vivo of purified preparations of murine macrophage colony stimulating factor-1, recombinant murine granulocyte-macrophage colony stimulating factor and natural and recombinant murine interleukin 3 without and with pretreatment of mice with purified iron-saturated human lactoferrin.

The influence of purified natural colony stimulating factor-1 (CSF-1), purified recombinant granulocyte-macrophage (GM)-CSF, purified recombinant interleukin 3 (IL3) and natural IL3 were assessed in mice that were untreated or pretreated with purified iron-saturated human lactoferrin (LF) in order to first suppress myelopoiesis in the mice. S1/S1d mice responded to recombinant GM-CSF and recombinant IL3 in a manner similar to the response of their +/+ littermates. These 4 factors increased the cycling status of hematopoietic progenitors in vivo. The effects were more noticeable if myelopoiesis was first decreased by LF. The effects do not appear to be due to endotoxin contamination. It cannot be discerned from these studies whether the effects are direct ones on the progenitor cells or indirect ones mediated through growth-factor releasing accessory cells. It is possible that effects can be both direct and indirect.

Animals↗

PubMed1986

The influence of oxygen tension on the long-term growth in vitro of haematopoietic progenitor cells from human cord blood.

Growth of low density human cord blood cells in long-term suspension culture was evaluated at incubation conditions of 5% carbon dioxide in approximately 20% (normal incubator) oxygen tension or in 5% (low) oxygen tension. During the first 5 weeks there was no difference in the numbers of morphologically recognizable cells grown at either oxygen tension, while growth was superior from weeks 5 to 8 at approximately 20% oxygen tension. For the first 5 weeks, growth of granulocyte-macrophage progenitors (CFU-GM) was superior at 5% oxygen tension during the long-term and semi-solid culture phases and least impressive in the long-term and semi-solid cultures incubated at approximately 20% oxygen. This trend was reversed after 5 weeks and after 8 weeks there were no detectable CFU-GM in suspension cultures at 5% oxygen while steady state levels of CFU-GM were maintained for greater than 12 weeks in suspension cultures at approximately 20% oxygen. Semi-solid cultures for erythroid (BFU-E) and multipotential (CFU-GEMM) progenitors were incubated at approximately 20% oxygen only. During the first 4 weeks, the growth of BFU-E and CFU-GEMM was superior at 5% oxygen during long-term culture. Numbers of these cells decreased by week 5 and at this time growth was better in the long-term cultures grown at approximately 20% oxygen. By week 6, no BFU-E or CFU-GEMM were detectable. Thus, growth of cord blood at low oxygen tension gives an initial enhancement in output of progenitor cells, but this appears to be at the expense of continued production.

Cells, Cultured↗

PubMed1986

Lactoferrin: affinity purification from human milk and polymorphonuclear neutrophils using monoclonal antibody (II 2C) to human lactoferrin, development of an immunoradiometric assay using II 2C, and myelopoietic regulation and receptor-binding characteristics.

Several investigators have now confirmed our original report demonstrating the myelopoietic suppressive activity of lactoferrin (LF) in vitro. In order to further clarify this activity, we used the recently produced and purified neutralizing antibody (II 2C) to LF to set up an immunoradiometric assay specific for LF and to affinity purify LF from lysates of peripheral blood polymorphonuclear neutrophils (PMN) obtained from healthy donors. Iron-saturated purified PMN LF was as active as iron-saturated affinity purified milk LF as a suppressor of the release of granulocyte-macrophage colony stimulating factors (GM-CSF) from mononuclear human peripheral blood leukocytes. The activities of both the PMN LF and milk LF were inactivated by preincubation with monoclonal anti-LF antibody (II 2C). In order to evaluate the methods of iron saturation of LF in vitro as measures of their functional activities, milk LF was iron saturated by four different methods, including ferric citrate, ferric ammonium sulphate, ferric chloride with nitriloacetate, and ferric chloride alone. The functional characteristics of all four preparations of LF saturated with iron in vitro were relatively equal and were more active than native LF. Resident mouse peritoneal macrophages separated into subpopulations of GM-CSF-producing cells by velocity sedimentation were evaluated for their LF-receptor binding capacity and for sensitivity to the suppression of GM-CSF release by LF. Iron saturated LF suppressed release of GM-CSF from only those fractions containing LF-receptor bearing cells, although not all fractions containing cells bearing receptors for LF responded to the suppressive activity of LF. These studies provide further evidence for the myelopoietic regulatory activity in vitro of PMN-derived LF, which is mediated through populations of mononuclear phagocytes having receptors for LF.

Animals↗

PubMed1986

Gamma interferon induces colony-forming cells of the human monoblast cell line U937 to respond to inhibition by lactoferrin, transferrin, and acidic isoferritins.

Human gamma interferon (HuIFN gamma) was assessed for its capacities to induce MHC class-II antigens on U937 cells and to induce responsiveness of U937 colony-forming cells (CFC) to the suppressive influences of lactoferrin (LF), transferrin (TF), and acidic isoferritins (AIF). U937 cells grown in suspension culture for many years demonstrated variable percentages of MHC class-II antigen+ cells (6%-42%) as determined by analysis with monoclonal anti-MHC class-II and the FACS IV when checked at different times. The percentage of U937 cells positive for MHC class-II antigens, as well as the density distribution of MHC class-II antigens on these cells, was increased by preincubating the cells for 72 h in the presence of 10(-6) M indomethacin and increasing concentrations of natural HuIFN gamma up to 20-40 U/ml. Colony formation by cells preincubated in control medium plus indomethacin for 72 h was not decreased by treating cells with monoclonal anti-MHC class-II plus complement (C'), high specific activity tritiated thymidine (3HTdr), LF, TF, or AIF. After preincubation of U937 cells with natural HuIFN gamma plus indomethacin in suspension culture for 72 h, colony formation in semisolid medium was reduced 40%-50% by treating the cells with anti-MHC class-II plus C', 3HTdr, LF, TF, or AIF. Colony formation was not reduced further by LF, TF, or AIF, after cells were pretreated with anti-MHC class-II (1:200 dilution) plus C' or 3HTdr. Increasing concentrations of HuIFN gamma up to 20 U/ml increased the percentage of MHC class-II antigen+ U937 CFC as well as the sensitivity of U937 CFC to suppression by LF, TF, and AIF. The inducing activities of natural HuIFN gamma were due to the IFN gamma itself since the inducing activity of natural HuIFN gamma was inactivated by pretreatment with a monoclonal antibody against natural HuIFN gamma. Also the inducing effects were mimicked by recombinant HuIFN gamma. The suppressive effects of LF, TF, and AIF on colony formation were blocked by treating the cells with monoclonal anti-MHC class-II (1:50 dilution, but not 1:200 dilution) in the absence of C'. The suppressive effect of TF only was blocked by pretreating cells with a monoclonal antibody against the TF receptor. U937 cells can be used as a model to study the regulatory mechanisms of action of HuIFN gamma, LF, TF, and AIF.

Cell Line↗

PubMed1986

Prostaglandin E counteracts the gamma interferon induction of major histocompatibility complex class-II antigens on U937 cells and induction of responsiveness of U937 colony-forming cells to suppression by lactoferrin, transferrin, acidic isoferritins, and prostaglandin E.

The established human monoblast or early monocyte cell line, U937, was evaluated for modulating influences of prostaglandin E2 (PGE2) on human gamma interferon (HuIFN gamma) induction of MHC class-II (Ia) antigens on U937 cells and the HuIFN gamma induction of responsiveness of U937 colony-forming cells (CFC) to inhibition by lactoferrin (LF), transferrin (TF), acidic isoferritins (AIF), and prostaglandin E (PGE). U937 CFC were induced to a state of responsiveness to the suppressive influences of PGE by HuIFN gamma. When MHC class-II antigens were induced on U937 cells and the cells sorted on the fluorescence activated cell sorter (FACS) IV into positive and negative cells, colony formation by the MHC class-II antigen+ population of cells was suppressed by LF, TF, AIF, and PGE2. Colony formation by the sorted population of MHC class-II antigen- cells was not influenced significantly by LF, TF, AIF, or PGE2. When PGE was present in the suspension culture for 72 h with U937 cells exposed to HuIFN gamma plus indomethacin, it blocked the induction of MHC class-II antigens as well as the associated inhibition of U937 CFC by LF, TF, AIF, and PGE2.

Cell Line↗