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.

Characterization of adult human marrow hematopoietic progenitors highly enriched by two-color cell sorting with My10 and major histocompatibility class II monoclonal antibodies

Monoclonal antibodies, My10 (HPCA-1) and major histocompatibility class II (HLA-DR), were used to enrich and phenotype normal human marrow colony-forming unit: granulocyte-macrophage (CFU-GM), burst-forming unit: erythroid (BFU-E), and multipotential colony-forming unit: granulocyte-erythroid-macrophage-megakaryocyte (CFU-GEMM) progenitor cells. Nonadherent low density T lymphocyte-depleted marrow cells were sorted on a Coulter Epics 753 dye laser flow cytometry system with the use of Texas Red-labeled anti-My10 and phycoerythrin conjugated anti-HLA-DR. Cells were separated into populations with nondetectable expression of antigens (DR-My10-) or with constant expression of one antigen and increasing densities of the other antigen. More than 98% of the CFU-GM, BFU-E, and CFU-GEMM were found in fractions containing cells expressing both HLA-DR and My10 antigens. The cloning efficiency (CE) of cells in the DR-My10- cell fraction was 0.01%. In the antigen-positive sorted fractions, the CE was highest (up to 47%) in the fractions of cells expressing high My10 and low DR (My10 DR+) antigens and was lowest (2.5%) in the fraction of cells expressing low My10 and low DR (My10+DR+) antigens. Populations of cells varying in the density of HLA-DR, but not My10, antigens varied in the proportion and types of progenitor cells present. When My10-positive cells were sorted for HLA-DR density expression, the CE for CFU-GM was similar in the DR+ and DR++ fractions, but most of the BFU-E and CFU-GEMM were found in the DR+ fraction. Within the CFU-GM compartment, most of the eosinophil progenitors were found in the DR+ fraction, whereas a greater proportion of macrophage progenitors were detected in the DR++ fraction. CFU-GM and BFU-E in the fractions of cells positive for DR and My10 were assessed for responsiveness to the effects of recombinant human tumor necrosis factor-alpha, recombinant human interferon-gamma, and prostaglandin E1. Colony formation from CFU-GM was suppressed by the three molecules, and colony formation by BFU-E was suppressed by recombinant human tumor necrosis factor-alpha and interferon-gamma and enhanced, in the presence of T lymphocyte-conditioned medium, by prostaglandin E1 in all antigen-positive fractions.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of adult human marrow hematopoietic progenitors highly enriched by two-color cell sorting with My10 and major histocompatibility class II monoclonal antibodies

Monoclonal antibodies, My10 (HPCA-1) and major histocompatibility class II (HLA-DR), were used to enrich and phenotype normal human marrow colony-forming unit: granulocyte-macrophage (CFU-GM), burst-forming unit: erythroid (BFU-E), and multipotential colony-forming unit: granulocyte-erythroid-macrophage-megakaryocyte (CFU-GEMM) progenitor cells. Nonadherent low density T lymphocyte-depleted marrow cells were sorted on a Coulter Epics 753 dye laser flow cytometry system with the use of Texas Red-labeled anti-My10 and phycoerythrin conjugated anti-HLA-DR. Cells were separated into populations with nondetectable expression of antigens (DR-My10-) or with constant expression of one antigen and increasing densities of the other antigen. More than 98% of the CFU-GM, BFU-E, and CFU-GEMM were found in fractions containing cells expressing both HLA-DR and My10 antigens. The cloning efficiency (CE) of cells in the DR-My10- cell fraction was 0.01%. In the antigen-positive sorted fractions, the CE was highest (up to 47%) in the fractions of cells expressing high My10 and low DR (My10 DR+) antigens and was lowest (2.5%) in the fraction of cells expressing low My10 and low DR (My10+DR+) antigens. Populations of cells varying in the density of HLA-DR, but not My10, antigens varied in the proportion and types of progenitor cells present. When My10-positive cells were sorted for HLA-DR density expression, the CE for CFU-GM was similar in the DR+ and DR++ fractions, but most of the BFU-E and CFU-GEMM were found in the DR+ fraction. Within the CFU-GM compartment, most of the eosinophil progenitors were found in the DR+ fraction, whereas a greater proportion of macrophage progenitors were detected in the DR++ fraction. CFU-GM and BFU-E in the fractions of cells positive for DR and My10 were assessed for responsiveness to the effects of recombinant human tumor necrosis factor-alpha, recombinant human interferon-gamma, and prostaglandin E1. Colony formation from CFU-GM was suppressed by the three molecules, and colony formation by BFU-E was suppressed by recombinant human tumor necrosis factor-alpha and interferon-gamma and enhanced, in the presence of T lymphocyte-conditioned medium, by prostaglandin E1 in all antigen-positive fractions.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Protective influence of lactoferrin on mice infected with the polycythemia-inducing strain of Friend virus complex

Purified iron-saturated human lactoferrin (LF) was assessed in vivo for effects on the survival rates of C57BL X DBA/2 f1 (hereafter called BD2F1) (Fv-2sr) mice and titers of spleen focus-forming viruses (SFFV) in BD2F1 and DBA/2 (Fv-2ss) mice inoculated with the polycythemia-inducing strain of the Friend virus complex (FVC-P). LF prolonged the survival rates and decreased the titers of SFFV in mice given FVC-P. Titers of SFFV, assayed 14 days after administration of FVC-P, were measured by the spleen focus-forming unit assay in secondary mouse recipients. Decreases in titers of SFFV were apparent when LF was given in vivo as a single bolus dose of 200 micrograms within 2 h of the Friend virus complex (FVC), or as a total dosage of 200 micrograms given on days 1, 2, 4, 7, 9, and 11 after FVC-P, and to a lesser degree when LF was given as a total dosage of 200 micrograms on days 3, 4, 7, 9, and 11 after FVC-P. No decreases in titers of SFFV were detected when LF was given up to 3 days before or more than 3 days after FVC-P. LF did not appear to be directly inactivating the viruses as it did not inactivate the SFFV or the Friend murine leukemia helper virus in vitro. The results suggest that the protective effect of LF in vivo is probably due to an action on cells responding to the FVC or to an action on cells which influence the cells responding to the FVC or which influence the virus. It has been shown elsewhere that LF decreases the percentage of marrow and spleen hematopoietic progenitor cells that are in DNA synthesis in vivo and this may be the means by which the protective effect of LF is mediated in mice given the FVC.

Bovine pancreatic polypeptide as an antagonist of muscarinic cholinergic receptors

In dispersed acini from rat pancreas, it was found that bovine pancreatic polypeptide (BPP) and its C-fragment hexapeptide amide (PP-6), at concentrations of 0.1 and 30 microM, respectively, could significantly inhibit amylase secretion stimulated by carbachol (P less than 0.01 or 0.05, respectively), and this inhibition by BPP was dose dependent. 45Ca outflux induced by carbachol was also inhibited by BPP or PP-6, but they had no effect on cholecystokinin octapeptide- (CCK-8) or A23187-stimulated 45Ca outflux. BPP was also capable of displacing the specific binding of [3H]quinuclidinyl benzilate to its receptors, and it possessed a higher affinity (ki 35 nM) than carbachol (Ki 1.8 microM) in binding with M-receptors. It is concluded from this study that BPP acts as an antagonist of muscarinic cholinergic receptors in rat pancreatic acini. In addition, BPP inhibited the potentiation of amylase secretion caused by the combination of carbachol plus secretin or vasoactive intestinal peptide. This may be a possible explanation of the inhibitory effect of BPP on secretin-induced pancreatic enzyme secretion shown in vivo, since pancreatic enzyme secretion stimulated by secretin under experimental conditions may be the result of potentiation of enzyme release produced by the peptide in combination with a cholinergic stimulant.

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.

The comparative enhancing effects of prostaglandin E1 on colony formation by erythroid progenitor (BFU-E) cells from bone marrow of mice differing in the Fv-2 locus

Prostaglandin E1(PGE1) was assessed for its colony enhancing effects on erythroid (BFU-E) progenitor cells and for its colony suppressive effects on granulocyte-macrophage (CFU-GM) progenitor cells from bone marrows of mice differing in the Fv-2 locus. The Fv-2 locus has been reported by others to control the proportion of BFU-E, but not of CFU-GM, in DNA synthesis. PGE1 significantly enhanced erythroid colony formation by marrow cells from DBA/2 (Fv-2ss), C57BL/6 (Fv-2rr) and BDF1 (Fv-2rs) mice, but the DBA/2 cells were more sensitive to the PGE1 enhancing effects than were cells from C57BL/6 or BDF1 mice. The enhanced sensitivity of DBA/2 cells to PGE1 was associated with the higher cycling rate of DBA/2-BFU-E in comparison with C57BL/6- and BDF1-BFU-E, and removal of S-phase DBA/2-BFU-E by pulse exposure of cells to high specific activity tritiated thymidine in vitro eliminated the erythroid colony enhancing effects of PGE1. The differences in sensitivity of BFU-E from mice differing in the Fv-2 locus to the effects of PGE1 were verified using Fv-2 congenic mice. In contrast, no significant differences were noted in sensitivity of CFU-GM from these different mouse strains, including mice congenic for the Fv-2 locus, to the suppressive effects of PGE1. This correlated with the similar cycling characteristics of CFU-GM from these mice, and the non-cycle specific effects of PGE1 on mouse CFU-GM. These studies substantiate further the regulatory effects of the Fv-2 locus on mouse erythroid progenitor cells which are a manifestation of the cycling rates of these cells.

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.

The influence of purified recombinant human heavy-subunit and light-subunit ferritins on colony formation in vitro by granulocyte-macrophage and erythroid progenitor cells

Purified recombinant human heavy subunit (rHF, acidic) and recombinant human light subunit (rLF, basic) ferritins were assessed for their effects in vitro on colony formation by normal human granulocyte-macrophage (CFU-GM) and erythroid (BFU-E) progenitor cells. The purity of the samples was confirmed by electrophoresis in both nondenaturing and denaturing conditions and silver staining. Concentrations of 10(-8) to 10(-10) mol/L rHF caused an approximately 40% significant decrease in colony formation. Some significant activity was detected at 10(-11) mol/L, and activity was lost at 10(-12) mol/L. In contrast, rLF had no significant activity at 10(-8) to 10(-16) mol/L. rHF was significantly active against mouse bone marrow CFU-GM to concentrations as low as 10(-8) to 10(-9) mol/L. The inhibitory activity of rHF was inactivated with three different monoclonal antibodies recognizing the heavy subunit of ferritin, but not with two monoclonal antibodies recognizing the light subunit of ferritin. The inhibitory activity of rHF was similar in the absence or presence of serum, monocytes, and T lymphocytes. We and others have shown an association of a glycosylated natural acidic isoferritin (AIF) with inhibitory activity, but since the rHF was expressed in Escherichia coli and did not bind to concanavalin A, glycosylation of AIF is not an absolute prerequisite for this activity. These results demonstrate that rHF has suppressive activity in vitro and substantiate our original observations using purified natural acidic isoferritins.

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.

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.

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.

Effects of recombinant human tumor necrosis factor alpha, recombinant human gamma-interferon, and prostaglandin E on colony formation of human hematopoietic progenitor cells stimulated by natural human pluripotent colony-stimulating factor, pluripoietin alpha, and recombinant erythropoietin in serum-free cultures

The influences of pure human pluripotent colony-stimulating factor, highly purified pluripoietin alpha, pure recombinant human tumor necrosis factor alpha, pure recombinant human gamma-interferon, and natural prostaglandin E1 (PGE1) were evaluated on colony formation of multipotential and erythroid progenitor cells in the presence of recombinant erythropoietin and hemin and on colony formation of granulocyte-macrophage progenitors in normal human marrow cultured in the presence or absence of serum. Serum was replaced by bovine serum albumin, iron-saturated transferrin, cholesterol, and calcium chloride. Increasing concentrations of pluripotent colony-stimulating factor and pluripoietin alpha stimulated increasing numbers of colonies from nonadherent low-density T-lymphocyte-depleted cells in the absence and presence of serum. Growth was usually greater in the presence of serum and on a unit basis pluripoietin alpha was more active than pluripotent colony-stimulating factor. Recombinant human tumor necrosis factor alpha and recombinant human gamma-interferon suppressed colony formation colony forming unit-granulocyte-macrophage, burst forming unit-erythroid, and colony forming unit-granulocyte-erythroid-macrophage-megakaryocyte; PGE1 suppressed colony formation by colony-forming unit-granulocyte-macrophage, stimulated colony formation by burst forming unit-erythroid, and had no effects on colony formation by colony forming unit-granulocyte-erythroid-macrophage-megakaryocyte in both serum-containing and serum-free medium. The PGE1 enhancing effects on erythroid colony formation required T-lymphocytes. Thus, results are similar using serum-containing and serum-free cultures of human bone marrow cells and serum-free defined culture medium can be used to study the mechanism of action of purified natural and recombinant growth and suppressor molecules in vitro.

Enhancement of the proliferation of human marrow erythroid (BFU-E) progenitor cells by prostaglandin E requires the participation of OKT8-positive T lymphocytes and is associated with the density expression of major histocompatibility complex class II antigens on BFU-E

The relationship between major histocompatibility complex class II antigens (MHC class II, eg, HLA-DR, Ia), T lymphocytes, and the enhancement of erythroid colony formation from BFU-E by prostaglandin E was analyzed using normal bone marrow cells. In primary methylcellulose culture, the addition of prostaglandin E1 (PGE1) to unseparated buffy coat, low-density, or nonadherent low-density (NAL) marrow cells resulted in an enhancement of the total number of erythroid (BFU-E) colonies observed. Treatment of bone marrow cells with a monoclonal antihuman MHC class II antibody plus complement (C') resulted in a reduction of the total number of colonies by approximately 50% and abrogation of the enhancing effect of PGE1. Analysis of accessory cell requirements by depletion of both adherent cells and sheep erythrocyte rosetting lymphocytes (E+ cells) and reconstitution using C' or anti-MHC class II antibody plus C'-treated T cell-depleted NAL (NALT-) marrow cells and E+ cell populations treated with C' or anti-MHC class II antibody plus C' demonstrated a requirement for MHC class II antigen-T cells, but not adherent cells, and a requirement for MHC class II antigen + BFU-E in order to observe the enhancing effect of PGE1 on erythroid colony formation. Positive selection of BFU-E in NALT- bone marrow expressing differing density distributions of MHC class II antigens was accomplished with monoclonal anti-MHC class II antibodies and sorting with a fluorescence-activated cell sorter (FACS). Addition of E+ cells to the different populations of MHC class II antigen+ NALT- cells demonstrated that the PGE-enhancing effects on erythroid colony formation were directly related to increasing density distributions of MHC class II antigens on BFU-E. Colony formation by BFU-E expressing a low density distribution of MHC class II antigens or having no detectable MHC class II antigens, as determined by FACS analysis, was not enhanced by PGE1 in the presence of MHC class II antigen-positive or -negative T cells.

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)

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)

Pluripoietin alpha: a second human hematopoietic colony-stimulating factor produced by the human bladder carcinoma cell line 5637

We have identified a factor constitutively produced by the human bladder carcinoma cell line 5637, which has the following capacities: to induce the differentiation of the human promyelocytic leukemic cell line HL-60; to induce the expression of chemotactic peptide receptors in leukemic cells as well as in normal peripheral blood granulocytes; to function as a chemoattractant for neutrophils as well as, under certain conditions, inhibiting their migration; to support the growth of eosinophil and granulocyte/macrophage progenitors, which is maximal when scored at day 14; and to support the growth of human mixed pluripotent progenitors and erythroid bursts from normal human bone marrow. This factor has a molecular size of 32 kDa by gel filtration and 16.5 kDa by NaDodSO4/PAGE. We have termed this factor pluripoietin alpha.

Low-dose (diagnostic-like) x-ray as a cocarcinogen in mouse colon carcinoma

To test the hypothesis that low-dose (diagnostic-like) radiation may play the part of a cocarcinogen in inflammatory bowel disease, we used four groups of BALB/C mice, (a control, dimethylhydrazine, dimethylhydrazine plus low-dose radiation, and low-dose radiation). We found no protective or carcinogen effects of the radiation in combination with dimethylhydrazine compared to dimethylhydrazine alone. This type of negative experimental finding is important in that individuals with inflammatory bowel disease have many diagnostic x-rays throughout life.

Activities derived from established human myeloid cell lines reverse the suppression of cell line colony formation by lactoferrin and transferrin

Myeloid cell lines were evaluated for the release of substances needed for colony formation by their own colony-forming cells (CFC) and by other myeloid cell lines. Dialyzed U937 conditioned medium (CM) had no effect on the cloning efficiency of U937 cells, whether or not U937 CFC had been induced for MHC class-II antigens by preincubation of these cells for 72 h with indomethacin and human gamma interferon (HuIFN gamma). Dialyzed U937 CM, however, restored colony formation of HuIFN gamma-induced U937 cells suppressed by lactoferrin (LF) or transferrin (TF). Dialyzed U937 CM did not restore colony formation of U937 cells suppressed by acidic isoferritins (AIF) or prostaglandin E2 (PGE2). Detection of the growth-restoring effects of U937 CM required that U937 CM be prepared in the presence of indomethacin or that the CM be dialyzed to remove inhibitors of U937 colony formation. Dialyzed U937 CM did not inactivate LF. Dialyzed U937 CM did not stimulate or enhance colony formation of normal human bone marrow granulocyte-macrophage (CFU-GM), erythroid (BFU-E), or multipotential (CFU-GEMM) progenitor cells, but did contain potent inhibitory activity against these progenitor cells. HL-60, EM2, EM3, and K562 cells were also evaluated. HL-60-, EM3-, and K562-CFC that were not preincubated with HuIFN gamma did not express MHC class-II antigens, and colony formation by these cells was not influenced by LF, TF, or AIF. Noninduced EM2-CFC constitutively expressed MHC class-II antigens, and colony formation by these cells was suppressed by LF, TF, and AIF. After induction of MHC class-II antigens on HL-60- and EM3-CFC by HuIFN gamma, colony formation by these cells was suppressed by LF, TF, and AIF. Colony formation by HuIFN gamma-induced EM2 cells was more responsive to inhibition by LF, TF, and AIF than was colony formation by noninduced EM2 cells. K562 cells were not induced into a responsive state to LF, TF, or AIF by HuIFN gamma. Dialyzed CM from HL-60, EM2, and EM3 cells contained activities that restored colony formation by their own LF-suppressed CFC. The activities present in dialyzed CM from U937, HL-60, EM2, and EM3 cells may be similar since they could each restore LF-suppressed colony formation of U937, HL-60, EM2, or EM3 cells.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Biological activities of a human pluripotent hemopoietic colony stimulating factor on normal and leukemic cells

We studied the biological effects of pluripoietin, a human pluripotent hemopoietic colony-stimulating factor (CSF) purified from the 5637 bladder carcinoma cell line. We found that this human CSF appears to be a unique hemopoietic growth factor, differing from interleukin 3 (IL-3) by virtue of its leukemia differentiating activity in mouse and man, and from mouse granulocyte CSF, which does have differentiation-inducing activity, but lacks pluripoietic activity. In addition, differences from IL-3 were observed in cross-species activity on normal and leukemic cells.

Comparative influences of phytohemagglutinin-stimulated leukocyte conditioned medium, hemin, prostaglandin E, and low oxygen tension on colony formation by erythroid progenitor cells in normal human bone marrow

The comparative influences of phytohemagglutinin-stimulated leukocyte conditioned medium (PHALCM), hemin, prostaglandin E1 (PGE1), and growth of cells at low oxygen tension (5% O2) were evaluated for their capacity to enhance colony formation in vitro from normal human bone marrow erythroid progenitor cells (BFU-E). Each treatment enhanced colony formation by itself, and the combinations of treatments resulted in an additive enhancing effect on erythroid colony formation. Removal of T-lymphocytes from the bone marrow sample ablated the enhancing activity of PGE1, but did not influence the enhancing activities of PHALCM, hemin, and growth at low oxygen tension. The results suggest that the mechanisms of action of these various erythroid colony-enhancing effects may be different.

Constitutive production of leukemia differentiation, colony-stimulating, erythroid burst-promoting, and pluripoietic factors by a human hepatoma cell line: characterization of the leukemia differentiation factor

Conditioned medium (CM) obtained from a human hepatoma cell line, SK-HEP-1, contains colony-stimulating factors (CSFs) active on murine and human bone marrow-derived granulocyte and macrophage colony-forming units (CFU-GM) and a factor capable of inducing granulocyte-macrophage differentiation (GM-DF) of murine myelomonocytic leukemic cells WEHI-3B(D+) and human promyelocytic leukemic cells HL-60 when assayed in semisolid agar cultures. The human active granulocyte-macrophage colony-stimulating factor (GM-CSF) for day 7 CFU-GM and the GM-DF for WEHI-3B(D+) and for HL-60 are not separable by acrylamide agarose column chromatography, eluting at an apparent molecular weight between 20,000 and 35,000 daltons, or by isoelectric focusing (isoelectric point, pH 5.4). In addition, SK-HEP-1 CM contains erythroid burst-promoting activity (BPA) and a factor that promotes the growth of human mixed colonies. SK-HEP-1 cells, which grow as an adherent monolayer, appear not to be endothelial or monocytic in origin since by immunofluorescent staining they are negative for Ia (HLA-DR), monocyte antigen 1 and 2, lysozyme, and factor VIII-related antigen. Positive immunofluorescent staining for keratin and fibronectin suggests the possibility that SK-HEP-1 is an epithelial cell line. Constitutive production of GM-DF as well as other hematopoietic activities including GM-CSF, erythroid BPA, and an activity that promotes the growth of human mixed colony progenitors by a human epithelial tumor cell line, SK-HEP-1, suggests that this cell line is a valuable resource for both large-scale production of these factors and the cloning of the gene(s) that code for these regulators.

Biological characterization of a granulomonopoietic enhancing activity derived from cultured human lipid-containing macrophages

We describe the biologic characteristics of an activity produced by human monocyte-derived lipid-containing cells (MDLCCs) that enhances the colony-forming capacity of granulocyte-macrophage progenitors (CFU-GM). Medium conditioned by well-developed MDLCCs (at day 21 to day 28 of cultivation) was added to bone marrow cultures containing GCT cell line-conditioned medium (GCT-CM) or other material as a source of granulocyte-macrophage colony-stimulating factors (GM-CSFs). MDLCC-conditioned medium (CM) had no detectable granulocyte-macrophage colony-stimulating activity (GM-CSA), but it contained an activity that enhanced the colony number in both day 7 and day 14 CFU-GM cultures. Dose-response curves for GCT-CM in the presence of MDLCC-CM demonstrated that this enhancing effect occurred at concentrations of GM-CSFs that stimulate maximal CFU-GM growth. This enhancing effect was seen with both granulocytic and monocytic progenitor cells. It was titratible and required the continuous presence of MDLCC-CM from initiation of culture. No enhancement was noted when MDLCC-CM was added 48 hours after plating. The enhancement still occurred when marrow cells were first incubated with MDLCC-CM and GCT-CM was added at later times. Neither the enhancing activity nor its production was dependent on horse serum contained in MDLCC culture medium. The enhancing effect was also seen when other sources of GM-CSA were used: medium conditioned by 5637 cell line, phytohemagglutinin-stimulated lymphocytes (PHAL), or placenta tissue. Furthermore, this enhancing activity appeared to be specific for CFU-GM. Addition of MDLCC-CM to mixed and erythroid cultures, stimulated by suboptimal and optimal concentrations of PHAL-CM did not modify the number of mixed colonies or erythroid bursts. This granulomonopoietic enhancing activity contained in MDLCC-CM was heat stable (56 degrees C and 75 degrees C for 30 minutes) and nondialyzable (3,500 and 14,000 molecular weight cut off tubing). Its production was increased by treating MDLCC with lipopolysaccharide (5 micrograms/mL) or zymosan (60 micrograms/mL) and inhibited by lactoferrin (10(-7) mol/L). The production of a granulomonopoietic enhancing activity by MDLCCs represents the demonstration of another positive feedback regulator of myelopoiesis involving the monocyte-macrophage system.

Effects of in vitro purging with 4-hydroperoxycyclophosphamide on the hematopoietic and microenvironmental elements of human bone marrow

We describe the effects of 4-hydroperoxycyclophosphamide (4-HC) on the hematopoietic and stromal elements of human bone marrow. Marrow cells were exposed to 4-HC and then assayed for mixed (CFU-Mix), erythroid (BFU-E), granulomonocytic (CFU-GM), and marrow fibroblast (CFU-F) colony-forming cells and studied in the long-term marrow culture (LTMC) system. The inhibition of colony formation by 4-HC was dose and cell-concentration dependent. The cell most sensitive to 4-HC was CFU-Mix (ID50 31 mumol/L) followed by BFU-E (ID50 41 mumol/L), CFU-GM (ID50 89 mumol/L), and CFU-F (ID50 235 mumol/L). In LTMC, a dose-related inhibition of CFU-GM production was noted. Marrows treated with 300 mumol/L 4-HC were completely depleted of CFU-GM but were able to generate these progenitors in LTMC. Marrow stromal progenitors giving rise to stromal layers in LTMC, although less sensitive to 4-HC cytotoxicity, were damaged by 4-HC also in a dose-related manner. Marrows treated with 4-HC up to 300 mumol/L, gave rise to stromal layers composed of fibroblasts, endothelial cells, adipocytes, and macrophages. Cocultivation experiments with freshly isolated autologous hematopoietic cells showed that stromal layers derived from 4-HC-treated marrows were capable of sustaining the long-term production of CFU-GM as well as controls.

IN CONCLUSION

(1) Hematopoietic progenitors cells, CFU-Mix, BFU-E, and CFU-GM, are highly sensitive to 4-HC, whereas marrow stromal progenitor cells are relatively resistant. (2) Marrows treated with 300 mumol/L 4-HC that are depleted of CFU-Mix, BFU-E, and CFU-GM can generate CFU-GM in LTMC, suggesting that most primitive hematopoietic stem cells (not represented by CFU-Mix) are spared by 4-HC up to this dose. (3) Consequently, the above colony assays are not suitable tools for predicting pluripotent stem cell survival after 4-HC treatment in vitro.

Human megakaryocytes. V. Changes in the phenotypic profile of differentiating megakaryocytes

Human megakaryocytes were studied for phenotypic changes occurring throughout differentiation using a panel of monoclonal antibodies raised against marrow megakaryocytes and blood platelets. 11 monoclonal antibody preparations were selected for restricted specificity against megakaryocytes and/or platelets after screening by immunofluorescence, complement-mediated cytolysis, and solid phase enzyme-linked immunosorbent assay. The expression of the cellular epitopes recognized by these reagents enabled the identification of three levels of megakaryocyte maturation characterized by distinct immunologic phenotypes. Based upon their reactivities against megakaryocytic cells at different ontogenetic levels, monoclonal antibodies were operationally categorized into three groups. Group A consisted of six different monoclonal antibodies that recognized antigens on the colony-forming unit-megakaryocyte (CFU-Mk), in vitro grown colony megakaryocytes, and early immature marrow megakaryocytes, only, and did not detect their respective epitopes on either mature megakaryocytes or platelets. A monoclonal antibody categorized in group B detected a cell antigen expressed by megakaryocytic cells at all maturational levels, but which is lost or suppressed during terminal differentiation and is not expressed on blood platelets. Group C included four different monoclonal antibodies raised against platelets that recognized antigenic determinants expressed on the CFU-Mk, colony megakaryocytes, early and mature megakaryocytes, and platelets. Three group C monoclonal antibodies (PC-1, PC-3, and PC-4) were specific for platelet glycoprotein IIb/IIIa. Additionally, group C monoclonal antibody PC-2 was unique in that it showed partial reactivity against the clonable progenitor for the erythroid series (BFU-E). Recognition of discrete phenotypic changes in differentiating megakaryocytes will enable multiparameter analyses of these cells as well as the study of factors regulating the dynamics of megakaryocytopoiesis in health and disease.

Purification and biochemical characterization of human pluripotent hematopoietic colony-stimulating factor

Pluripotent hematopoietic colony-stimulating factor (pluripotent CSF), a protein that is constitutively produced by the human bladder carcinoma cell line 5637, has been purified from low serum (0.2% fetal calf serum)-containing conditioned medium. The purification involved sequential ammonium sulfate precipitation, ion-exchange chromatography, gel filtration, and reversed-phase high-performance liquid chromatography. The purified protein has a molecular weight of 18,000 in NaDodSO4/polyacrylamide gel electrophoresis, both by the silver staining technique and by elution of biological activity from a corresponding gel slice, and has an isoelectric point of 5.5. Pluripotent CSF supports the growth of human mixed colonies, granulocyte-macrophage colonies, and early erythroid colonies and induces differentiation of the human promyelocytic leukemic cell line HL-60 and the murine myelomonocytic leukemic cell line WEHI-3B (D+). The specific activity of the purified pluripotent CSF in the granulocyte-macrophage colony assay is 1.5 X 10(8) units/mg of protein.

OKT3 monoclonal antibody induces production of colony-stimulating factor(s) for granulocytes and macrophages in cultures of human T lymphocytes and adherent cells

OKT3 monoclonal antibody (mab) recognizes a membrane antigen associated with the T cell antigen recognition receptor, and is known to be mitogenic and to induce lymphokine production. Our studies demonstrate the ability of OKT3 mab to induce from cultures of human T lymphocytes supplemented with adherent cells the production of colony-stimulating factor(s) for granulocytes and macrophages (GM-CSF) and interferon-gamma (IFN-gamma), an inhibitor of clonal growth of hematopoietic progenitor cells. As has been shown for the mitogenic and IFN-gamma-inducing activity of OKT3 mab, the induction of GM-CSF release in cultures of T cells is strictly dependent on the presence of adherent cells. However, the concentrations of OKT3 mab required for optimal GM-CSF production (50 ng/ml) were found to be 80-fold higher than those sufficient for maximal IFN-gamma production, proliferation, and interleukin 2 production. IFN-gamma activity induced by OKT3 mab partially inhibited colony and cluster formation from progenitor cells of granulocytes and macrophages in vitro. Therefore, neutralization of the IFN-gamma by monoclonal anti-human-IFN-gamma antibody before assay of conditioned medium in bone marrow cultures significantly enhanced the detection of GM-CSF. Kinetic studies demonstrated maximal cumulative GM-CSF production in response to optimal OKT3 mab concentrations on days 4 through 6 in cultures of T cells supplemented with 15% adherent cells. Highly enriched OKT4+ and OKT8+ T cell subsets co-cultured with adherent cells in the presence of OKT3 mab both produced GM-CSF and IFN-gamma and showed similar dose-response curves to OKT3 mab. The requirement for the presence of adherent cells could not be overcome by the addition of purified interleukin 1 or macrophage supernatants. Studies using irreversible inhibitors of DNA (mitomycin C) or protein biosynthesis (emetine-HCl) revealed the necessity of intact DNA synthesis and translation in mononuclear cells to produce GM-CSF in response to OKT3 mab. Loss of GM-CSF production was observed when either adherent cells or T lymphocytes were treated with emetine before co-culture with untreated cells of the other population in the presence of OKT3 mab. In contrast, mitomycin C reduced GM-CSF production significantly when T cells, but not adherent cells, were pretreated. These results suggest that T lymphocytes and adherent cells closely cooperate in the production of GM-CSF induced by OKT3 mab.

Abnormalities in myelopoietic regulatory interactions with acidic isoferritins and lactoferrin in mice infected with Friend virus complex: association with altered expression of Ia antigens on effector and responding cells

The regulation of myelopoiesis was evaluated in B6D2F1 mice inoculated with Friend virus complex (spleen focus-forming virus plus helper virus) or helper virus alone by analyzing acidic isoferritin (AIF) and lactoferrin (LF) interactions with target cells. Under normal conditions, AIF suppresses colony and cluster formation by an Ia-antigen-positive cycling subpopulation of mouse granulocyte-macrophage progenitor cells (CFU-GM). Under the same conditions, the release of AIF-inhibitory activity and granulocyte-macrophage colony stimulatory factors (GM-CSF) from an Ia-antigen-positive subpopulation of monocytes and macrophages is suppressed by LF. Within one to two days after inoculation in vivo with Friend virus complex or helper virus, mouse CFU-GM become insensitive in vitro to suppression by purified human AIF as well as crude mouse AIF, and by four days, bone marrow, spleen, and thymus cells of these mice release much greater quantities of AIF-inhibitory activity than the cells from mice injected with control medium. The Friend virus complex itself has no influence in vitro on CFU-GM from normal mice. In addition, the release of AIF-inhibitory activity from bone marrow, spleen, and resident peritoneal cells and the release of GM-CSF from resident peritoneal cells of mice infected with Friend virus complex are not suppressed by LF. The inability of AIF to suppress colony formation by bone marrow and spleen CFU-GM from mice infected with Friend virus complex is associated with the loss of Ia (I-A subregion) antigens from CFU-GM, even though CFU-GM are in cycle. The nonresponsiveness of bone marrow, spleen, and peritoneal cells from these mice to LF suppression of AIF release and the inability of LF to influence GM-CSF release from peritoneal cells is associated with loss of Ia antigens from these cells. The above abnormalities are similar to the defects noted using cells from patients with leukemia. These results suggest that mice infected with Friend virus complex can serve as a model for investigating abnormalities in cell regulation and their relationships to disease progression.

OKT3 monoclonal antibody induces production of colony-stimulating factor(s) for granulocytes and macrophages in cultures of human T lymphocytes and adherent cells

OKT3 monoclonal antibody (mab) recognizes a membrane antigen associated with the T cell antigen recognition receptor, and is known to be mitogenic and to induce lymphokine production. Our studies demonstrate the ability of OKT3 mab to induce from cultures of human T lymphocytes supplemented with adherent cells the production of colony-stimulating factor(s) for granulocytes and macrophages (GM-CSF) and interferon-gamma (IFN-gamma), an inhibitor of clonal growth of hematopoietic progenitor cells. As has been shown for the mitogenic and IFN-gamma-inducing activity of OKT3 mab, the induction of GM-CSF release in cultures of T cells is strictly dependent on the presence of adherent cells. However, the concentrations of OKT3 mab required for optimal GM-CSF production (50 ng/ml) were found to be 80-fold higher than those sufficient for maximal IFN-gamma production, proliferation, and interleukin 2 production. IFN-gamma activity induced by OKT3 mab partially inhibited colony and cluster formation from progenitor cells of granulocytes and macrophages in vitro. Therefore, neutralization of the IFN-gamma by monoclonal anti-human-IFN-gamma antibody before assay of conditioned medium in bone marrow cultures significantly enhanced the detection of GM-CSF. Kinetic studies demonstrated maximal cumulative GM-CSF production in response to optimal OKT3 mab concentrations on days 4 through 6 in cultures of T cells supplemented with 15% adherent cells. Highly enriched OKT4+ and OKT8+ T cell subsets co-cultured with adherent cells in the presence of OKT3 mab both produced GM-CSF and IFN-gamma and showed similar dose-response curves to OKT3 mab. The requirement for the presence of adherent cells could not be overcome by the addition of purified interleukin 1 or macrophage supernatants. Studies using irreversible inhibitors of DNA (mitomycin C) or protein biosynthesis (emetine-HCl) revealed the necessity of intact DNA synthesis and translation in mononuclear cells to produce GM-CSF in response to OKT3 mab. Loss of GM-CSF production was observed when either adherent cells or T lymphocytes were treated with emetine before co-culture with untreated cells of the other population in the presence of OKT3 mab. In contrast, mitomycin C reduced GM-CSF production significantly when T cells, but not adherent cells, were pretreated. These results suggest that T lymphocytes and adherent cells closely cooperate in the production of GM-CSF induced by OKT3 mab.

Preparation and characterization of monoclonal antibodies recognizing two distinct differentiation antigens (Pro-Im1, Pro-Im2) on early hematopoietic cells

A series of monoclonal antibodies recognizing myeloid differentiation antigens were prepared by immunizing Balb/c mice with HL-60 cells. Hybrids secreting antibodies reactive with HL-60 cells but unreactive with peripheral blood mononuclear cells were isolated and further cloned. One clone was found to produce an IgG2a antibody recognizing an 85,000-dalton molecular weight surface glycoprotein, and a second clone was found to produce an IgM antibody recognizing a heat-stable determinant present on a glycolipid. We have termed these antigens Pro-Im1 and Pro-Im2, respectively (Pro for using HL-60 promyelocytes as an immunogen and Im for the presence of these antigens on immature cells). alpha Pro-Im1 and alpha Pro-Im2 were used to investigate the surface expression and tissue distribution of these two antigens. Pro-Im1 and Pro-Im2 were found to be brightly expressed on a fraction of fetal liver hematopoietic and bone marrow cells. Both antibodies mediated complement-dependent inhibition of CFU-GM, BFU-E, and CFU-GEMM formation assayed by soft agar colony and burst formation, indicating the expression of these antigens by early hematopoietic precursor cells. This was further confirmed by the induction of HL-60 cells by TPA to differentiate into more mature monocytes and macrophages, accompanied by the loss of both antigens. Pro-Im1 and Pro-Im2 were absent from peripheral blood monocytes, erythrocytes, and platelets, but Pro-Im2 was expressed on granulocytes. Both antigens were absent from thymocytes and peripheral T cells. Cytofluorographic analysis suggested their absence from peripheral blood B cells but that both were expressed on a minority of tissue B cells. Analysis of 150 cases of various myeloid and lymphoid malignancies demonstrated Pro-Im1 and Pro-Im2 expression on myeloblasts and promyelocytes from some acute myelogenous leukemias as well as some B cell malignancies, suggesting that these antigens are shared by early hematopoietic cells and a subset of B cells.

Modulation of the expression of HLA-DR (Ia) antigens and the proliferation of human erythroid (BFU-E) and multipotential (CFU-GEMM) progenitor cells by prostaglandin E

The relationship between the presence of Ia-like antigens on human CFU-GEMM and BFU-E, and their responsiveness to the regulatory effects of AIF and PGE have been studied using normal human bone marrow cells. In primary methylcellulose culture the addition of 10(-6)-10(-9) M PGE1 results in the enhancement of the total number of BFU-E detected, with no observed effect on the number of CFU-GEMM. Addition of acidic isoferritins to primary cultures results in an approximately 50% inhibition of both BFU-E and CFU-GEMM proliferation. Removal of Ia+ cells by cytotoxic treatment with monoclonal antihuman HLA-DR (Ia) antibody plus C' resulted in: (a) reduction of total CFU-GEMM and BFU-E by approximately 50%, (b) abrogation of the enhancing effect of PGE on BFU-E, and (c) detection of populations of CFU-GEMM and BFU-E that are no longer sensitive to inhibition by AIF. Culture of marrow cells in suspension culture at 37 degrees C for 24 h prior to methylcellulose culture resulted in the loss of detectable Ia antigen on BFU-E and CFU-GEMM, loss of their responsiveness to AIF, loss of the enhancing effect of PGE on BFU-E, and the inability to detect cycling cells. Exposure of marrow cells to PGE, however, during the suspension phase augmented the total number of BFU-E, and CFU-GEMM detected and resulted in the detection of S-phase cells, expression of Ia antigens of both BFU-E and CFU-GEMM, and restoration of the ability to detect BFU-E and CFU-GEMM sensitivity to inhibition by AIF. After suspension culture with PGE, no further enhancement of BFU-E by PGE was observed. These results indicate that the expression of Ia antigens is important in the regulation of BFU-E and CFU-GEMM proliferation and add further evidence for a role for PGE in controlling progenitor cell Ia-antigen expression, cell cycle and, as a consequence, their proliferative capacity.

Specific inhibition of in vitro lymphocyte transformation by an anti-pan T cell (gp67) ricin A chain immunotoxin

The toxin A chain of ricin has been conjugated by a disulfide bond to a murine monoclonal antibody that recognizes the gp67kD antigen present on 95% of peripheral T lymphocytes. The immunotoxin retains both functions of its component parts: it binds to human peripheral blood lymphocytes, and it inhibits protein synthesis in a cellfree reticulocyte system. The immunotoxin has been evaluated for its ability to inhibit in vitro T lymphocyte transformation. In the presence of 20 mM NH4Cl, the immunotoxin decreases lymphocyte proliferation in response to phytohemagglutinin to less than 8% of untreated controls. The proliferative response in mixed lymphocyte culture and the development of allocytotoxic T cells is also dramatically inhibited by this immunotoxin. Monoclonal antibody alone does not inhibit these responses. Specificity of the immunotoxin has been established: the effect of the immunotoxin can be blocked by unconjugated monoclonal antibody, but not by a control monoclonal antibody that recognizes another T lymphocyte differentiation antigen or by a control monoclonal antibody that does not recognize human peripheral blood leukocytes. Treatment of human bone marrow cells with the immunotoxin preserves hematopoietic progenitor cells, as measured by granulocyte-macrophage, erythroid, and multipotential hematopoietic progenitor cell assays. These results indicate that an anti-pan T lymphocyte-ricin A chain immunotoxin is an effective agent against immunocompetent T lymphocytes in vitro, and may be an effective agent for use in clinical bone marrow transplantation.

Specific inhibition of in vitro lymphocyte transformation by an anti-pan T cell (gp67) ricin A chain immunotoxin

The toxin A chain of ricin has been conjugated by a disulfide bond to a murine monoclonal antibody that recognizes the gp67kD antigen present on 95% of peripheral T lymphocytes. The immunotoxin retains both functions of its component parts: it binds to human peripheral blood lymphocytes, and it inhibits protein synthesis in a cellfree reticulocyte system. The immunotoxin has been evaluated for its ability to inhibit in vitro T lymphocyte transformation. In the presence of 20 mM NH4Cl, the immunotoxin decreases lymphocyte proliferation in response to phytohemagglutinin to less than 8% of untreated controls. The proliferative response in mixed lymphocyte culture and the development of allocytotoxic T cells is also dramatically inhibited by this immunotoxin. Monoclonal antibody alone does not inhibit these responses. Specificity of the immunotoxin has been established: the effect of the immunotoxin can be blocked by unconjugated monoclonal antibody, but not by a control monoclonal antibody that recognizes another T lymphocyte differentiation antigen or by a control monoclonal antibody that does not recognize human peripheral blood leukocytes. Treatment of human bone marrow cells with the immunotoxin preserves hematopoietic progenitor cells, as measured by granulocyte-macrophage, erythroid, and multipotential hematopoietic progenitor cell assays. These results indicate that an anti-pan T lymphocyte-ricin A chain immunotoxin is an effective agent against immunocompetent T lymphocytes in vitro, and may be an effective agent for use in clinical bone marrow transplantation.

HLA-DR human histocompatibility leukocyte antigens-restricted lymphocyte-monocyte interactions in the release from monocytes of acidic isoferritins that suppress hematopoietic progenitor cells

Acidic isoferritins, which under normal conditions are released from monocytes and macrophages, have a suppressive effect in vitro on granulocyte-macrophage, erythroid, and multipotential hematopoietic progenitor cells. Cell interactions modulating the release of acidic isoferritin-inhibitory activity (AIFIA) from human monocytes were investigated using the bone marrow granulocyte-macrophage progenitor cells as a target cell assay for assessing AIFIA. Monocytes, in the absence of T lymphocytes, released AIFIA when allowed to condition culture medium at 10(4) or higher concentrations of monocytes/ml. However, subpopulations of T lymphocytes modulated the release of AIFIA from monocytes. OKT8+- and OKT4+-T lymphocytes were obtained from E-rosette-positive lymphocytes by using T lymphocyte subset-specific monoclonal antibodies in either a complement-dependent cytotoxicity test to select negatively for the cells or by selection using a "panning" procedure. OKT8+-T lymphocytes suppressed completely and OKT4+-T lymphocytes enhanced the constitutive release of AIFIA from monocytes. OKT4+ lymphocytes also induced the release of AIFIA from concentrations of 10(3) monocytes/ml which did not release measurable amounts of AIFIA by themselves. The release of AIFIA from monocytes involved HLA-DR+-monocytes and -T lymphocytes. Pulsing monocytes with monoclonal antibodies to framework determinants on HLA-DR molecules, in the absence of complement, did not influence the constitutive release of AIFIA. Pulsing monocytes or T lymphocyte subpopulations with such antibodies, in the absence of complement, blocked the suppressing and inducing activities of the appropriate subpopulations of T lymphocytes. Monoclonal antibodies to common determinants shared by HLA-A, B, and C molecules did not block these cellular interactions. Treating monocytes and T lymphocytes in a complement-dependent cytotoxicity test with dilutions of the anti-HLA-DR antibodies that did not block the cellular interactions removed the populations of monocytes constitutively releasing AIFIA and the T lymphocyte subsets modulating this release. Modulation of the release of AIFIA from monocytes by T lymphocyte subpopulations required the use of autologous cells, cells from HLA-identical siblings, or unrelated donors matched for HLA-DR. Matching for only one HLA haplotype gave partial responses and this was seen in testing cells from related individuals as well as among unrelated test combinations. These cellular interactions were not detected with HLA-DR-incompatible cells differing for two HLA-DR antigens. Admixture of such HLA-DR- incompatible allogeneic cells did not interfere with the regulation of AIFIA release in the autologous cell interactions. Thus, release of AIFIA from monocytes is restricted genetically by HLA-DR at the level of T lymphocyte-monocyte interactions. The genetic determinants on the HLA-class II molecules that induce stimulation in vitro in mixed lymphocyte culture (i.e., HLA-D), however, were not involved in this effort.

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)

Cardiac hemochromatosis: beneficial effects of iron removal therapy. An echocardiographic study

The echocardiographic (echo) features of idiopathic hemochromatosis (IH) were studied in 22 patients. Results were compared with a control group of 22 patients without heart disease. Statistically significant increases in left ventricular (LV) mass, end-diastolic and end-systolic diameters of the left ventricle and in left atrial dimension were observed in patients with IH; significant changes of systolic function indexes (decrease in fractional shortening and ejection fraction and increase in distance of the E point to the septum) were seen as well. These echo abnormalities were mainly seen in patients with abnormal electrocardiograms. In 11 patients with IH, iron removal therapy was carried out by means of periodic phlebotomies. In patients with impaired LV function at the beginning of therapy, comparison between measurements of the initial echo and posttreatment echo showed significant improvement in LV diameters, fractional shortening, ejection fraction, distance from the E point to the septum, LV mass and left atrial dimension.

Comparative analysis of the influences of human gamma, alpha and beta interferons on human multipotential (CFU-GEMM), erythroid (BFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells

Preparations of human interferon (HuIFN) immune (gamma) (2 X 10(7) units/mg protein), HuIFN leukocyte (alpha) (1.4 X 10(8) units/mg protein) and HuIFN fibroblasts (beta) (10(6) U/mg protein) were assessed for their influence on colony formation of human hematopoietic progenitor cells: colony forming unit-granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM), burst forming unit-erythroid (BFU-E), day 7 colony forming unit granulocyte-macrophage (CFU-GM) and day 14 CFU-GM. Colony formation by CFU-GEMM and BFU-E was suppressed equally by the three preparations of HuIFN, but colony formation by CFU-GM was suppressed differentially. CFU-GM were, on the whole, more responsive to HuIFN gamma than HuIFN alpha, and HuIFN beta was least effective. HuIFN alpha, but not HuIFN gamma or HuIFN beta, suppressed colony formation from CFU-GM without also suppressing the total number of colonies plus clusters. This was due to an increase in the numbers of clusters formed in the presence of HuIFN alpha. The suppressive influence on colonies from CFU-GM by the preparations of HuIFN and the enhancement of clusters by HuIFN alpha was apparently equal for colonies and clusters of neutrophils, eosinophils, macrophages and neutrophils plus macrophages. The suppressive effects of HuIFN gamma were inactivated by a monoclonal antibody to HuIFN gamma and the suppressive and enhancing effects of HuIFN alpha were inactivated with a heteroantiserum to HuIFN alpha. Depletion of monocytes, T lymphocytes and B lymphocytes from the target bone marrow cells had no influence on the effects of the preparations of HuIFN. These results demonstrate that the effects of HuIFN gamma and HuIFN alpha are due to the HuIFN themselves and that these actions on the hematopoietic progenitor cells are probably not mediated through monocytes and/or lymphocytes.

The selective enhancing influence of hemin and products of human erythrocytes on colony formation by human multipotential (CFUGEMM) and erythroid (BFUE) progenitor cells in vitro

The influence of erythrocytes, extracts of erythrocytes and hemin was assessed on colony formation in vitro by human bone marrow multipotential (CFUGEMM), erythroid (BFUE) and granulocyte-macrophage (CFUGM) progenitor cells. Colony formation by CFUGEMM and BFUE present in the low density (less than 1.077 g/cm3) fraction of bone marrow cells was enhanced in the presence of high density (greater than 1.077 g/cm3) bone marrow cells. Erythrocytes, but not leukocytes, present in the high density fraction of cells were responsible for this enhancing effect on colony formation. Extracts of erythrocytes or hemin substituted for the enhancing activity of the intact erythrocytes. This enhancing activity was not apparent on colony formation by bone marrow CFUGM. These results demonstrate a selective enhancing influence on colonies derived from CFUGEMM and BFUE. Erythrocyte products allow the detection of such colonies and may play a role in the growth stimulation of CFUGEMM and BFUE.

Comparative analysis of the influences of human gamma, alpha and beta interferons on human multipotential (CFU-GEMM), erythroid (BFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells

Preparations of human interferon (HuIFN) immune (gamma) (2 X 10(7) units/mg protein), HuIFN leukocyte (alpha) (1.4 X 10(8) units/mg protein) and HuIFN fibroblasts (beta) (10(6) U/mg protein) were assessed for their influence on colony formation of human hematopoietic progenitor cells: colony forming unit-granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM), burst forming unit-erythroid (BFU-E), day 7 colony forming unit granulocyte-macrophage (CFU-GM) and day 14 CFU-GM. Colony formation by CFU-GEMM and BFU-E was suppressed equally by the three preparations of HuIFN, but colony formation by CFU-GM was suppressed differentially. CFU-GM were, on the whole, more responsive to HuIFN gamma than HuIFN alpha, and HuIFN beta was least effective. HuIFN alpha, but not HuIFN gamma or HuIFN beta, suppressed colony formation from CFU-GM without also suppressing the total number of colonies plus clusters. This was due to an increase in the numbers of clusters formed in the presence of HuIFN alpha. The suppressive influence on colonies from CFU-GM by the preparations of HuIFN and the enhancement of clusters by HuIFN alpha was apparently equal for colonies and clusters of neutrophils, eosinophils, macrophages and neutrophils plus macrophages. The suppressive effects of HuIFN gamma were inactivated by a monoclonal antibody to HuIFN gamma and the suppressive and enhancing effects of HuIFN alpha were inactivated with a heteroantiserum to HuIFN alpha. Depletion of monocytes, T lymphocytes and B lymphocytes from the target bone marrow cells had no influence on the effects of the preparations of HuIFN. These results demonstrate that the effects of HuIFN gamma and HuIFN alpha are due to the HuIFN themselves and that these actions on the hematopoietic progenitor cells are probably not mediated through monocytes and/or lymphocytes.