Biomedical subjects

H E Broxmeyer

Publications and source records attributed to H E Broxmeyer.

At least 361 records · Page 20Linked to original sources

PubMed1985

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

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

Cells, Cultured↗

PubMed1985

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.

Alprostadil↗

PubMed1984

Colony assays of hematopoietic progenitor cells and correlations to clinical situations.

The production of blood cells is a dynamic process that is noticeably aberrant during disease. The availability of colony assays in vitro that allow detection of hematopoietic stem and progenitor cells for the neutrophil, monocyte-macrophage, erythroid and/or megakaryocyte lineages has been of importance for the present understanding of the mechanisms controlling the proliferation, self-renewal capacity, and differentiation of morphologically nonrecognizable immature cells which give rise to the mature progeny circulating in the blood. It is through the use of these assays that the existence of potentially relevant stimulatory and inhibitory feedback interactions has been demonstrated. Abnormalities in these interactions, which may be of significance during leukemia and related disorders, have been uncovered. This communication will discuss regulatory interactions detected via the colony assays, their potential relevance physiologically and pathologically, and the use of these assays for diagnosis, prognosis, and for monitoring the clinical status of patients.

Animals↗

PubMed1984

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.

Antilymphocyte Serum↗

PubMed1984

Lactoferrin acts on I-A and I-E/C antigen+ subpopulations of mouse peritoneal macrophages in the absence of T lymphocytes and other cell types to inhibit production of granulocyte-macrophage colony stimulatory factors in vitro.

The relationship between Ia antigens on mouse resident peritoneal macrophages and the ability of lactoferrin (LF) to inhibit the production of granulocyte-macrophage colony stimulatory factors (GM-CSF) from these cells was investigated. Detection of the suppressive influence of LF on release of GM-CSF from greater than or equal to 10(5) macrophages/ml/plate required that the conditioned media being assessed for GM-CSF be prepared in the presence of indomethacin and/or be preincubated with anti-ferritin antiserum to respectively stop production of E-type prostaglandins and to remove acidic isoferritin-inhibitory activities that can mask the effects of LF. Treatment of mouse macrophages with monoclonal antibodies to the I-A and I-E/C subregions of Ia antigens in a complement C-dependent cytotoxicity assay killed less than 15% of the cells, but removed all Ia antigen+ macrophages and reduced GM-CSF production by approximately 50%. LF decreased GM-CSF production by untreated macrophages by approximately 50%, but had no effect on macrophages insensitive to treatment with anti-Ia plus C. Macrophages left at 37 degrees C for 5 and 24 hr were not killed by treatment with monoclonal anti-Ia plus C and GM-CSF production by these macrophages was not suppressed by LF. Treatment of macrophages with monoclonal anti-H-2K or anti-Mac-1 plus C reduced GM-CSF production greater than 95%. Anti-I-A, -I-E/C, -H-2K, or -Mac-1, in the absence of C, had no effect on viability of macrophages or on production of GM-CSF, but anti-I-A and -I-E/C each blocked the inhibitory action of LF. Lower concentrations of these antibodies could block the action of LF when anti-I-A and anti-I-E/C were mixed together better than when they were each used separately. The removal of Thy-1.2+ cells from unseparated or adherent peritoneal cells resulted in populations of cells that were up to 100% positive for nonspecific esterase, and did not influence GM-CSF production from these cells, the reduction of GM-CSF from these cells by LF, or the reduction of GM-CSF by the removal of Ia antigen+ cells. The results were similar whether or not T cells were removed from the assay marrow by treatment with antibodies Ly-1.1, Ly-2.2, and Qa4 plus C.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1984

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.

Antibodies, Monoclonal↗

PubMed1984

Negative regulators of hematopoiesis.

It is apparent from the above that molecules can have more than one role, but these roles need not be mutually exclusive. A clear understanding of cell regulations will require knowledge of all interacting molecules and the cells producing and responding to these molecules. This will be especially important when studies on the roles of these molecules in maintenance of long-term marrow and blood cultures are investigated further.

Animals↗

PubMed1984

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

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

Animals↗

PubMed1984

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.

Animals↗

PubMed1984

Serum inhibitor in systemic lupus erythematosus associated with aplastic anemia.

Hematologic complications of systemic lupus erythematosus (SLE) usually involve peripheral destruction of blood elements. We report a case of SLE-associated aplastic anemia in which an IgG complement-dependent antibody, obtained from the patient's disease-phase serum but not remission-phase serum, suppressed growth of granulocyte-macrophage progenitor cells from bone marrow of normal donors in vitro. Therapy with plasmapheresis and immunosuppression resulted in lasting remission.

Adolescent↗

PubMed1983

Acidic isoferritins do not suppress differentiation of mouse myeloid leukemic M1 cells.

The differentiation of mouse myeloid leukemia line cells (M1) into macrophages or granulocytes has been reported. Resistant M1 cells which did not differentiate even with a high concentration of inducer of differentiation were isolated from M1 cells. The conditioned medium of the resistant M1 cells (RCM) inhibited the induction of differentiation of M1 cells and the formation of macrophage and granulocyte colonies of normal mouse bone marrow cells. Acidic isoferritins known as negative regulators of normal bone marrow cells (CFU-GM) failed to inhibit the induction of differentiation and growth of M1 cells. The RCM treated with anti-acidic isoferritin serum could inhibit the induction of differentiation of M1 cells as did the untreated RCM. The activities, in RCM, inhibiting growth and differentiation of the normal bone marrow cells were partly neutralized by treatment with the antiserum but most of the activities remained. These results suggest that growth and differentiation of the mouse myeloid leukemia M1 cells are not regulated by acidic isoferritins and other inhibitory activities affecting normal bone marrow colony formation, in addition to acidic isoferritins, are released from M1 cells.

Animals↗

PubMed1983

Acidic isoferritin inhibitory activity: a normal granulopoietic regulator within long term mouse bone marrow cultures.

Long term murine bone marrow cultures maintain orderly granulopoiesis for several months. Assay of cell free supernatant obtained at weekly feedings from control cultures demonstrated endogeneously produced acidic isoferritin inhibitory activity. Addition of 10(9) M acidic isoferritin inhibitory activity to long term cultures gave a trend toward fewer nonadherent cells and fewer colony forming units-granulocyte/macrophage (CFU-GM) per flask, but this was not statistically significant. Media conditioned by each fraction of velocity sedimentation separated non-adherent cells gave two discrete peaks of inhibition at 5.6 and 6.8-9 mm/h, respectively. Acidic isoferritin inhibitory activity was restricted to the sharp peak at 5.6 mm/h. Media conditioned by each fraction of velocity sedimentation separated adherent layer cells did not contain assayable acidic isoferritin inhibitory activity. Tests for an endogeneously produced soluble inactivator of acidic isoferritin inhibitory activity were negative. The constitutive production and release of acidic isoferritin inhibitory activity by a restricted population of cells within long term marrow cultures supports the concept of this molecule as a normal hematopoietic regulator.

Animals↗

PubMed1983

Antigenically distinct subpopulations of myeloid progenitor cells (CFU-GM) in human peripheral blood and marrow.

Two types of progenitor cells of the human granulocytic and monocytic lineages (CFU-GM) can be distinguished by using mouse monoclonal antibodies against human hemopoietic cells. Type 1 CFU-GM contribute all of the peripheral blood CFU-GM as well as a small fraction of bone marrow CFU-GM and express surface antigens recognized by "anti-lymphomonocytic" monoclonal antibodies S3-13 and S17-25 but not the antigens recognized by R1B19 and WGHS-29-1 (two monoclonal antibodies that react with all the cells of the granulocytic lineage). Type 2 CFU-GM are present only in the marrow and react with S3-13, R1B19, and WGHS-29-1. Partial reactivity with S17-25 was observed only in the complement-dependent cytotoxicity test. In vitro culture of type 1 CFU-GM in liquid medium in the presence of granulocyte-macrophage colony-stimulatory factor (GM-CSF) generates colony-forming cells that have the surface phenotype of type 2 CFU-GM. This finding supports the idea of two different stages of maturation of myelomonocytic progenitor cells represented by type 1 and type 2 CFU-GM.

Adult↗

PubMed1983

Biosynthesis of ferritin subunits from different cell lines of HL-60 human promyelocytic leukaemia cells and the release of acidic isoferritin-inhibitory activity against normal granulocyte-macrophage progenitor cells.

Biosynthesis of acidic isoferritins was investigated in human promyelocytic HL-60 cells, characterized by diploid (2C), tetraploid (4C) and mixed diploid--tetraploid (2C-4C) DNA cell lines. The three cell lines were studied for the biosynthesis of ferritin and its subunits and for the release of acidic isoferritin-inhibitory activity against normal CFU-GM before and after addition of DMSO. While the tetraploid and mixed diploid--tetraploid cell lines synthesized more H-(Mr = 21) than L-subunits (Mr = 19) after induction, the tetraploid line synthesized more H-subunit before and after induction, compared to the diploid line. The release of acidic isoferritin-inhibitory activity was greater before than after induction in both cell lines, but the tetraploid cell line released more acidic isoferritin-inhibitory activity consistent with its greater production of Mr = 21 subunit. However, after induction no inhibitory activity could be detected from the diploid cells and much less activity was detected with the tetraploid cells, suggesting that differentiation caused a decrease in production of acidic isoferritin-inhibitory activity.

Animals↗

PubMed1983

The production of colony stimulating activity by monocyte enriched fractions from murine continuous bone marrow culture adherent layers.

The production of colony stimulating activity (GM-CSA) within murine continuous bone marrow cultures was investigated by subjecting either the nonadherent or the adherent layer cells to separation by velocity sedimentation. The presence of GM-CSA in conditioned medium was defined by the support of granulocyte/macrophage colony formation in soft agar culture. Cell free conditioned medium from weekly feedings of intact continuous marrow cultures and medium conditioned by each fraction of velocity sedimentation separated, nonadherent cells did not contain assayable GM-CSA. However, medium conditioned by fractions of adherent layer cells with a modal sedimentation velocity of 8.8 mm/h (range 6.2-10.6 mm/h) contained GM-CSA. Cytochemical studies with Wright's-Giemsa and non-specific esterase stains in addition to immunofluorescent studies with anti-collagen III, anti-collagen IV and monoclonal anti-Mac I antibodies to define fibroblasts, endothelial cells and monocytes, respectively, demonstrated that the cells within the GM-CSA producing fractions were enriched with monocytes/macrophages. Fibroblasts and a small proportion of endothelial cells were also present. GM-CSA is produced within the microenvironment (adherent layer) of murine continuous marrow cultures. Either adherent layer monocytes and/or a monocyte-endothelial cell interaction account for the GM-CSA production.

Animals↗

PubMed1983

Association of cell cycle expression of Ia-like antigenic determinations on normal human multipotential (CFU-GEMM) and erythroid (BFU-E) progenitor cells with regulation in vitro by acidic isoferritins.

An association has been established between human Ia-like antigenic determinants, expression during DNA synthesis on multipotential (CFU-GEMM) and erythroid (BFU-E) progenitor cells, and the regulatory action of acidic isoferritins in vitro. Treatment of human bone marrow cells with monoclonal anti-Ia (NE1-011) plus complement inhibited colony formation of CFU-GEMM) and BFU-E by 50%-70%. Reduction of colonies was similar whether bone marrow cells were exposed to anti-Ia plus complement, high specific tritiated thymidine (3HTdr), or acidic isoferritins. No further decrease was apparent with 3HTdr or acidic isoferritins after Ia-antigen+ CFU-GEMM or BFU-E were removed, or with anti-Ia plus complement or acidic isoferritins after S-phase CFU-GEMM or BFU-E were removed. Anti-Ia, in the absence of complement, had no effect on colony formation but blocked the inhibition of CFU-GEMM and BFU-E by acidic isoferritins. Demonstration of Ia-antigens on BFU-E and inhibition of BFU-E by acidic isoferritins appeared to require the presence of phytohemmagglutinin leukocyte conditioned medium (PHA-LCM) in the culture medium during the 14-day incubation period. these results implicate Ia-antigen+ cells, acidic isoferritins, and PHA-LCM in the regulation of multipotential and erythroid progenitor cells in vitro.

Antibodies, Monoclonal↗

PubMed1983

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.

Antibodies, Monoclonal↗

PubMed1983

Suppression of mouse myelopoiesis by administration of human lactoferrin in vivo and the comparative action of human transferrin.

Purified human lactoferrin was assessed for its influence in vivo in untreated mice and in mice undergoing rebound myelopoiesis after sublethal dosages of Cytoxan. Fully iron-saturated lactoferrin suppressed the numbers of granulocytes and monocytes per femur, the numbers of granulocyte-macrophage progenitor cells (CFU-GM) per femur and spleen, and decreased the cycle status of femoral and splenic CFU-GM. These effects were detected after administration of lactoferrin i.v. or i.p. into untreated and Cytoxan-treated mice. The suppressive effects on cellularity and numbers of CFU-GM per femur were apparent to a greater degree in mice treated with Cytoxan, and the i.v. route appeared preferable to the i.p. route. Heat-treated lactoferrin, inactive in vitro, was inactive in vivo, but iron-depleted (apo-) lactoferrin, inactive in vitro, was active in vivo, suggesting that the apo-lactoferrin acquired the iron in vivo that was necessary to change it into an active form. Titration of the effects of lactoferrin in Cytoxan-treated mice demonstrated a plateau curve of suppression of nucleated cells and CFU-GM per femur with dosages ranging from 100 micrograms to 10(-4) micrograms lactoferrin per mouse, with loss of activity at 10(-5) micrograms. The suppressive effect of lactoferrin on cycle status of CFU-GM required concentrations of 10 micrograms or higher. The effects of lactoferrin were reversible with time, with the suppressive influence on cycling status being lost before that on numbers of CFU-GM per femur. Purified human transferrin was also assessed for its influence in mice undergoing rebound myelopoiesis. Transferrin decreased the nucleated cellularity and the number of CFU-GM per femur and per spleen, but had little or no influence on the cycling status of CFU-GM and differed in its temporal effect on myelopoiesis from that of lactoferrin. These results suggest that lactoferrin and transferrin suppress the number of progenitor cells moving into the CFU-GM compartment and lactoferrin suppresses the cycling status of cells within the CFU-GM compartment. These effects are probably mediated by an action on the production of factors necessary for movement of cells into, and cell cycling within, the CFU-GM compartment.

Animals↗