Mouse Lung Conditioned Medium Research Articles

Granulocyte/macrophage colony-stimulating factor from mouse lung conditioned medium. Purification of multiple forms and radioiodination.

Four forms of mouse granulocyte/macrophage colony-stimulating factor (GM-CSF) were purified 100,000-fold from mouse lung conditioned medium. Each of the CSF species stimulated the formation of both granulocyte and macrophage colonies, and half-maximal stimulation in the semi-solid mouse bone-marrow colony assay occurred at 1 pm. The four GM-CSF species exhibited similar charge microheterogeneity, focusing between pH 4.2 and pH 5.2. On SDS/polyacrylamide gels two of the GM-CSF sub-species had apparent Mr values of 23,000, and the other two, 21, 000. Treatment with neuraminidase decreased the Mr values of these two sets to 21,000 and 19,000 respectively. Incubation with endoglucosidase F decreased the charge heterogeneity and the Mr of all species to 16,500. A gas-phase radioiodination procedure was used to incorporate 2-3 atoms of 125I/molecule into purified GM-CSF without any loss of biological activity. The 125I-labelled GM-CSF was analysed on a microbore reversed-phase h.p.l.c. column to determine its specific radioactivity directly. This 125I-labelled GM-CSF molecule is suitable for cell-surface receptor-binding studies.

Reculturing of Cells from Primary CFU-C Colonies

This study was aimed at investigating whether cells of CFU-C derived colonies could form secondary colonies. Bone marrow cultures of volumes of agar medium between 25 microliter and 75 microliter contained in glass capillaries were stimulated with mouse lung-conditioned medium (MLCM) containing granulocyte/macrophage colony-stimulating factor (GM-CSF). Agar gels with colonies of up to greater than or equal to 20 were blown out into identical culture medium, completely dispersed on a whirl-mix to single cell suspensions, and used for establishing secondary agar cultures. In these secondary cultures considerable numbers of secondary granulocytic, mixed granulocytic/macrophage and macrophage colonies as well as numerous clusters arose. In contrast, when single colonies were recultured, only few secondary cell aggregates were formed. When primary cultures containing up to greater than or equal to 20 cell aggregates were used for serial reculture at intermittent intervals of 3 and 4 days, a 2-7-fold increase of colony-forming cells was found in tertiary cultures as was monitored by 7 day colony counts. And by use of different kinds of CSF-containing media, an over 4-fold increase of secondary over primary colonies was obtained with bovine lung-conditioned medium (BLCM) in primary and L-cell-conditioned medium (LCCM) in secondary 7 day cultures. Primary capillary cultures were found to be devoid of CFU-S. Also, setting up bone marrow cultures in petri dishes and stimulating with MLCM, growth of primary as well as secondary colonies was obtained. The results indicate some self-renewal potential of CFU-C in vitro.

43] Murine granulocyte-macrophage colony-stimulating factor

Publisher Summary This chapter discusses the murine granulocyte-macrophage colony-stimulating factor. The differentiation and proliferation of hemopoietic progenitor cells is highlighted, that it is dependent on a set of specific glycoproteins. One of these glycoproteins is granulocyte-macrophage colony-stimulating factor (GM-CSF), which stimulates the proliferation in vitro of specific murine hemopoietic progenitor cells to form colonies containing mature neutrophilic granulocytes and macrophages. GM-CSF occurs in animal sera and the culture medium from a variety of tissues. GM-CSF is purified from mouse lung conditioned medium (MLCM) and has an apparent molecular weight of 23,000. cDNA clones corresponding to the mRNA from the murine GM-CSF gene are obtained and fully sequenced. GM-CSF is distinct from several other hemopoietic growth factors such as multi-CSF (also called IL-3) which also stimulate the production of mature erythroid cells from erythroid precursors and the continuous proliferation of mast cell lines. The chapter further explains purification of GM-CSF.

Purification and partial amino acid sequence of asialo murine granulocyte-macrophage colony stimulating factor.

A procedure utilizing reversed-phase high-performance liquid chromatography is described for the purification of asialo granulocyte-macrophage colony stimulating factor (asialo-GM-CSF) from mouse lung-conditioned medium. In the purification, the partially purified factor was treated with neuraminidase to reduce charge heterogeneity due to variable degrees of sialation. Three active forms of the asialo factor were separated by the final reversed-phase liquid chromatography step. These each gave a single major band and several minor bands on polyacrylamide gel electrophoresis and had similar amino acid compositions. The specific activity of purified murine asialo-GM-CSF was approximately 8 X 10(9) colonies per mg of protein. Amino acid sequence determination of the major form gave a single amino-terminal sequence, which has been used to develop oligonucleotide probes for the isolation of two cDNA clones encoding GM-CSF. The nucleotide sequence of these two clones gave a deduced amino acid sequence almost identical with that determined for the amino terminus of asialo-GM-CSF and an amino acid composition very similar to that for asialo-GM-CSF.

Inhibitory activity in mouse lung-conditioned medium studied in the agar assay for bone marrow colony-forming cells: removal by vitamin C.

The growth of granulocyte/macrophage colony-forming cells (CFC) from bone marrow, with mouse lung-conditioned medium (LCM) as source of colony-stimulating factor, was tested in five strains of mice. Maximum stimulation of growth was usually obtained at a LCM dilution of 1:5 (final concentration, 1.8% vol/vol). Higher concentrations nearly always caused inhibition. The inhibitory activity was resistant to heating (56 degrees C, 30 min) and was not removed by dialysis, but could be extracted with chloroform, suggesting a lipophilic inhibitor of high molecular weight. On gel filtration (Sephadex G50) the stimulatory activity eluted in the first fraction, whereas the inhibitory activity could not be recovered. Ascorbic acid reduced or prevented the inhibition (optimum concentration, 0.45 mmol/l), and provides a convenient means of stabilizing the CFC agar assay system. In physiological conditions the vitamin might influence the responsiveness of CFC to growth-regulating factors.

Proliferative effects of purified granulocyte colony-stimulating factor (G-CSF) on normal mouse hemopoietic cells.

When granulocyte colony-stimulating factor (G-CSF), purified to homogeneity from mouse lung-conditioned medium, was added to agar cultures of mouse bone marrow cells, it stimulated the formation of small numbers of granulocytic colonies. At high concentrations of G-CSF, a small proportion of macrophage and granulocyte-macrophage colonies also developed. G-CSF stimulated colony formation by highly enriched progenitor cell populations obtained by fractionation of mouse fetal liver cells using a fluorescence-activated cell sorter, indicating that G-CSF probably acts directly on target progenitor cells. Granulocytic colonies stimulated by G-CSF were small and uniform in size, and at 7 days of culture were composed of highly differentiated cells. Studies using clonal transfer and the delayed addition of other regulators showed that G-CSF could directly stimulate the initial proliferation of a large proportion of the granulocyte-macrophage progenitors in adult marrow and also the survival and/or proliferation of some multipotential, erythroid, and eosinophil progenitors in fetal liver. However, G-CSF was unable to sustain continued proliferation of these cells to result in colony formation. When G-CSF was mixed with purified granulocyte-macrophage colony-stimulating factor (GM-CSF) or macrophage colony-stimulating factor (M-CSF), the combination stimulated the formation by adult marrow cells of more granulocyte-macrophage colonies than either stimulus alone and an overall size increase in all colonies. G-CSF behaves as a predominantly granulopoietic stimulating factor but has some capacity to stimulate the initial proliferation of the same wide range of progenitor cells as that stimulated by GM-CSF.

Eosinophil activation by colony-stimulating factor in man: metabolic effects and analysis by flow cytometry

Substantial increases in the killing capacity of human eosinophils after in vitro incubation with human placental conditioned medium (HPCM), a standard source of colony-stimulating factor (CSF), have recently been described. In this article, the interaction between HPCM and purified human eosinophils is analyzed by flow cytometry and by effects on iodination, superoxide production, and protein synthesis. HPCM increased the intensity of natural eosinophil autofluorescence (aFlu) (460 nm) after the absorption of ultraviolet light (360 nm) in a manner that was both time and dose dependent. Measured in arbitrary units, eosinophil aFlu was 72 +/- 7.3 (arithmetic mean +/- SEM) and 121 +/- 3.2 after 18-hr incubations in the absence or presence of HPCM, respectively. The activity in HPCM responsible for these changes cochromatographed on Ultrogel AcA44 columns with CSF and with the less hydrophobic variant of CSF (CSF-alpha) on phenyl Sepharose. Mouse spleen, but not mouse lung, conditioned medium was also active on human eosinophils in this assay. Both CSF-alpha and mouse spleen conditioned medium also contain eosinophil colony-stimulating activity (CSA), whereas inactive CSFs with no effect on mature eosinophils, CSF-beta, and mouse lung conditioned medium also lack eosinophil CSA. CSF-alpha stimulated superoxide production of resting eosinophils (from 0.03 +/- 0.03 to 0.47 +/- 0.08 nmole cytochrome-c reduced/10(5) eosinophils) and of eosinophils incubated with preopsonized zymosan (from 0.15 +/- 0.06 to 0.73 +/- 0.07). It also stimulated iodination by resting eosinophils (from 0.76 +/- 0.16 to 2.60 +/- 0.72 nmoles l/10(7) eosinophils/hr) and of eosinophils incubated with preopsonized zymosan (from 7.52 +/- 2.08 to 29.8 +/- 1.32). In contrast, CSF-beta was inactive in these assays. CSF-alpha also stimulated, between 2- and 15-fold, the new protein synthesis of eosinophils. Thus, substances that stimulate the differentiation of progenitor cells into eosinophils also interact with peripheral mature eosinophils, and the activation of postmitotic cells may be a physiologic role of CSF-like molecules.

Eosinophil Activation by Colony-Stimulating Factor in Man: Metabolic Effects and Analysis by Flow Cytometry

Substantial increases in the killing capacity of human eosinophils after in vitro incubation with human placental conditioned medium (HPCM), a standard source of colony-stimulating factor (CSF), have recently been described. In this article, the interaction between HPCM and purified human eosinophils is analyzed by flow cytometry and by effects on iodination, superoxide production, and protein synthesis. HPCM increased the intensity of natural eosinophil autofluorescence (aFlu) (460 nm) after the absorption of ultraviolet light (360 nm) in a manner that was both time and dose dependent. Measured in arbitrary units, eosinophil aFlu was 72 +/- 7.3 (arithmetic mean +/- SEM) and 121 +/- 3.2 after 18-hr incubations in the absence or presence of HPCM, respectively. The activity in HPCM responsible for these changes cochromatographed on Ultrogel AcA44 columns with CSF and with the less hydrophobic variant of CSF (CSF-alpha) on phenyl Sepharose. Mouse spleen, but not mouse lung, conditioned medium was also active on human eosinophils in this assay. Both CSF-alpha and mouse spleen conditioned medium also contain eosinophil colony-stimulating activity (CSA), whereas inactive CSFs with no effect on mature eosinophils, CSF-beta, and mouse lung conditioned medium also lack eosinophil CSA. CSF-alpha stimulated superoxide production of resting eosinophils (from 0.03 +/- 0.03 to 0.47 +/- 0.08 nmole cytochrome-c reduced/10(5) eosinophils) and of eosinophils incubated with preopsonized zymosan (from 0.15 +/- 0.06 to 0.73 +/- 0.07). It also stimulated iodination by resting eosinophils (from 0.76 +/- 0.16 to 2.60 +/- 0.72 nmoles l/10(7) eosinophils/hr) and of eosinophils incubated with preopsonized zymosan (from 7.52 +/- 2.08 to 29.8 +/- 1.32). In contrast, CSF-beta was inactive in these assays. CSF-alpha also stimulated, between 2- and 15-fold, the new protein synthesis of eosinophils. Thus, substances that stimulate the differentiation of progenitor cells into eosinophils also interact with peripheral mature eosinophils, and the activation of postmitotic cells may be a physiologic role of CSF-like molecules.

Stimulation of [ 3H]thymidine uptake in mouse marrow by granulocyte-macrophage colony stimulating factor from mouse lung conditioned medium

Stimulation of [ 3H]thymidine uptake in mouse marrow cells by a haematopoietic factor, granulocyte-macrophage colony stimulating factor from mouse lung conditioned medium, was used to follow the activity of the factor in the medium, and during its partial purification from the medium. The assay was performed in microtitre plates and found to be much easier and faster than conventional colony counting. The marrow cells were incubated in flat-bottomed plates in the presence of the factor for 5 days before labelling with [ 3H]thymidine (2 μCi/well, 5 Ci/mmole) for 6 h. Stimulation of the [ 3H]thymidine uptake was compared with the development of granulocyte-macrophage colonies in semisolid methylcellulose culture. The activity followed by both assays showed identical behaviour when subjected to ammonium sulphate precipitation, Sephadex gel filtration, concanavalin-A-Sepharose chromatography and polyacrylamide gel electrophoresis.

Analysis of purified fetal liver hemopoietic progenitor cells in liquid culture.

AbstractThe action of different types of colony‐stimulating factors (CSFs) on purified fetal hemopoietic progenitor cells in liquid cultures was studied. Three types of CSF were examined–pregnant mouse uterus extract (PMUE), which contains macrophage CSF; mouse lung conditioned medium (MLCM), which contains granulocyte‐macrophage CSF; and pokeweed mitogen‐stimulated spleen cell‐conditioned medium (PWM‐SCM), which contains ganulocyte‐macrophage, eosinophil, megakaryocyte, and erythroid CSFs. Without a source of CSF, the cells died within 48 hr, but with CSF, cells entered an exponential growth phase within 18 hr with a doubling time of about 12 hr. Althogh growth was best with PWM‐SCM, this appeared to be due to increased numbers of surviving cells during the early period of culture and a decreased lag phase rather than a shortening of the doubling time. With PWM‐SCM, the absolute increase in cell number was 40‐fold. Over the culture period of seven days, the blast cells also differentiated morphologically to end cells, although differentiation appeared to be highly asynchronous. With MLCM and PMUE, only cells in the granulocyte‐macrophage series were seen, but with PWM‐SCM, erythroid cells were also observed. PMUE neither stimulated nor allowed the survival for longer than two days of granulocyte or erythroid committed progenitors (CFC) but, in contrast, stimulated a marked increase in macrophage CFC, which were uniquely responsive to PMUE stimulation. The proliferation of these progenitors appeared to be actively inhibited by PWM‐SCM. Despite the inability of MLCM to stimulate mature erythroid cell production, it was able to stimulate the early proliferation of erythroid CFC as well as granulocyte‐macrophage CFC. PWM‐SCM was able to stimulate the early and late proliferation of all types of CFC.

The nature and action of granulocyte-macrophage colony stimulating factors

Granulocyte-macrophage colony stimulating factor (GM-CSF) stimulates the in vitro proliferation and differentiation of granulocytic and macrophage cells. This regulator is now known to act at other levels of hemopoietic regulation. The heterogeneity of GM-CSFs is not only related to the tissue of origin and the in vitro production method, but also to functional subclasses of the molecule that have distinct biologic specificities. Most adult mouse organs produce GM-CSF (mol wt 23,000), but a macrophage (M)-CSF has been detected in fetal conditioned medium (CM) and isolated from L-cell CM. Murine endotoxin serum appears to contain a M-CSF, GM-CSF, and G-CSF, the last of which cofractionates with a differentiation factor active on leukemic cells. Human GM-CSFs, G-CSF, and EO-CSFs active on human cells have been detected in a variety of CM, but as yet none have been purified. Again, there are subclasses of progenitor cells that respond to particular forms of human active CSFs. GM-CSF isolated from mouse lung CM stimulates multipotential progenitor cells, the initial proliferatin of progenitors in the erythroid, eosinophil, and megakaryocyte series, as well as mature cells in the GM series. While GM-CSF is also able to stimulate the differentiation of myeloid leukemic cells, other factors appear to be more potent in this respect. Information on the regulation of GM-CSF production, on the modulators of its action on specific target cells, and on its role in vivo will be required before the physiologic function of this molecule can be properly assessed.

The Nature and Action of Granulocyte-Macrophage Colony Stimulating Factors

Granulocyte-macrophage colony stimulating factor (GM-CSF) stimulates the in vitro proliferation and differentiation of granulocytic and macrophage cells. This regulator is now known to act at other levels of hemopoietic regulation. The heterogeneity of GM-CSFs is not only related to the tissue of origin and the in vitro production method, but also to functional subclasses of the molecule that have distinct biologic specificities. Most adult mouse organs produce GM-CSF (mol wt 23,000), but a macrophage (M)-CSF has been detected in fetal conditioned medium (CM) and isolated from L-cell CM. Murine endotoxin serum appears to contain a M-CSF, GM-CSF, and G-CSF, the last of which cofractionates with a differentiation factor active on leukemic cells. Human GM-CSFs, G-CSF, and EO-CSFs active on human cells have been detected in a variety of CM, but as yet none have been purified. Again, there are subclasses of progenitor cells that respond to particular forms of human active CSFs. GM-CSF isolated from mouse lung CM stimulates multipotential progenitor cells, the initial proliferatin of progenitors in the erythroid, eosinophil, and megakaryocyte series, as well as mature cells in the GM series. While GM-CSF is also able to stimulate the differentiation of myeloid leukemic cells, other factors appear to be more potent in this respect. Information on the regulation of GM-CSF production, on the modulators of its action on specific target cells, and on its role in vivo will be required before the physiologic function of this molecule can be properly assessed.

The effect of mouse lung granulocyte-macrophage colony-stimulating factor and other colony-stimulating activities on the proliferation and differentiation of murine bone marrow cells in long-term cultures.

The roles of colony-stimulating factors in long-term bone marrow cultures were studied and compared. After single additions of high concentrations of unpurified colony-stimulating activities to the cultures, rapid deterioration of the cultures was observed. This appears to result from contaminants in the stimulatory preparations. Cultures to which one purified colony-stimulating factor (csf) from endotoxin mouse lung-conditioned medium was added did not run down ten weeks after addition and were found to be the same as the controls. The deterioration of the cultures to which unpurified stimulators were added could not be accounted for by accelerated granulopoiesis leading to subsequent exhaustion of the cultures. The inability of purified CSF to affect the cellularity of the suspension cells did not result from instability or masking of the activity in the cultures, nor did CSF preferentially stimulate the cells within the adherent layer. The suspension cells responded to purified CSF after separation from the adherent cells. The data suggest that if CSFs are marrow stimulators, their effects in turn may be stringently regulated within the marrow.

Serum of lipopolysaccharide-treated mice contains two types of colony-stimulating factor, separable by affinity chromatography.

Serum from mice treated with bacterial lipopolysaccharide (LPS) was fractionated by Con A-Sepharose affinity chromatography, and assayed in vitro for colony-stimulating factor (CSF) using mouse bone marrow cells. The CSF failing to bind to concanavalin A-Sepharose (pool A) had similar biological properties to the unfractionated serum, i.e., it stimulated the formation of about equal numbers of granulocytic, mixed granulocyte-macrophage and macrophage colonies. The fraction eluted from the Con A-Sepharose column with alpha-methyl-D-glucopyranoside (pool B) had a steeper dose-response curve than either the unfractionated serum or the pool A CSF and most of the colonies were composed of macrophages. A mixture of the pool A and pool B CSFs stimulated colonies in a similar way as unfractionated serum and poolA. The apparent molecular weights of the two types of CSF were determined by two different gel-filtration procedures. Sephacryl S-200 gel-filtration suggested an apparent molecular weight of 85,000 for pool A CSF and 180,000 for pool B CSF. Gel-filtration on Sepharose CL-6B in the presence of guanidine hydrochloride (6M) yielded an apparent molecular weight of approximately 23,000 for pool A CSF and 33,000 for pool B CSF. The colony-forming cells (CFC) responding to pool B CSF were found to have a relatively high sedimentation velocity (peak sedimentation velocity 5.6--6.2 mm/hr) compared to the CFC responding to mouse-lung conditioned medium (MLCM) whose peak sedimentation velocity was between 4.0--4.5 mm/hour. The CFC responding to pool A CSF had an intermediate sedimentation velocity (peak 4.6--5.2 mm/hour). A time-course analysis of the morphology of clones or colonies in cultures stimulated with either MLCM or pool B CSF showed that the proportion of different colony types depends significantly on the incubation period and suggested that pool tb csf induced an early commitment of CFC towards macrophages differentiation.

Direct Stimulation by Purified GM-CSF of the Proliferation of Multipotential and Erythroid Precursor Cells

GM-CSF, purified from mouse lung-conditioned medium, stimulated granulocyte-macrophage colony formation but was unable to stimulate the formation of any type of pure or mixed erythroid colony in agar cultures of 12-day CBA fetal liver cells. However, initial incubation of cells for 2 days with purified GM-CSF, followed by addition of mouse spleen-conditioned medium (SCM), allowed the formation of up to 50% of the erythroid or mixed hemopoietic colonies expected in cultures stimulated from the outset by SCM. These GM-CSF-responsive colony-forming cells were not distinguishable from the remainder of cells forming erythroid or mixed colonies by sedimentation velocity or cell cycle status. From 302 clones stimulated to proliferate by purified GM-CSF, 25 formed erythroid or mixed hemopoietic colonies on transfer to cultures containing SCM. Clones initiated by SCM were unable to form erythroid or mixed colonies when transferred to cultures containing purified GM-CSF. Single cells from 12-day CBA fetal peripheral blood also were stimulated to proliferate by purified GM-CSF and subsequently formed pure or mixed erythroid colonies when SCM was added. GM-CSF is thus able to directly stimulate up to 5 cell divisions of at least 50% of detectable multipotential and early erythroid precursor cells.

BUOYANT DENSITY ANALYSIS OF MYELOID COLONY‐FORMING CELLS IN GERMFREE AND CONVENTIONAL MICE

Granulocyte-macrophage colony-forming cells (CFUc), in the bone marrow of germfree and conventioal CBA mice, were compared quantitatively and qualitatively. Cells were separated on the basis of their buoyant density by equilibrium centrifugation in continuous albumin density gradients. CFUc in the density subpopulations were detected by culture in agar containing three different types of colony stimulating factor (CSF). The sources of the CSF were post-endotoxin mouse serum (CSFES), mouse lung conditioned medium (CSFMLCM) and human urine (CSFHU). Mice were removed from the germfree environment and the buoyant density status of their CFUc was examined 1, 4 and 8 weeks later. No difference was found between germfree and conventional mice in the number of nucleated cells per femur or in their modal density. Neither was the number of CFUc per femur different. The cell cycle status of CFUc, as determined by the thymidine suicide technique was not significantly different. Functional heterogeneity was found among the density subpopulations for both groups of mice. This depended on the type of CSF. The density distribution of CFUc was significantly different in germfree mice. There were proportionately more low density CFUc. The mean modal density of CFUc under CSFES stimulation was less by 0.0045 g/cm3 in germfree mice. The removal of mice from the germfree environment resulted in a shift of the distribution to higher densities. The trend was towards the conventional situation. The significance of the buoyant density status of CFUc is discussed.

Comparative Effects in Mice of Purified Bacterial Cell-Wall Components on Granulocyte-Macrophage Progenitor Cells and Their Regulators

Abstract The effects were investigated in mice of the injection of chemically pure preparations of three structurally unrelated cell-wall components from Gram-negative bacteria (BCWC), lipid A, outer-membrane lipoprotein, and murein on humoral and cellular parameters of granulocyte-macrophage production. Analysis of granulocyte-macrophage progenitor cells (GM-CFC) from normal C57BL/6 mice by velocity sedimentation showed that these cells sedimented as a relatively uniform population with a peak sedimentation velocity between 4.2 and 4.5 mm/hr. Pretreatment of mice with murein caused no significant alteration of this profile. However, GM-CFC from mice injected with either lipid A or lipoprotein sedimented more rapidly than normal. The whole profile was broadened and more than one peak was observed. Sera from mice injected with any of the three components stimulated the growth of GM-CFC in vitro, and at high serum concentrations, the absolute number of colonies and the proportion of pure granulocytic, pure macrophage, and mixed colonies were very similar. However, serial dilution of the sera revealed a significant qualitative difference between post-lipid A serum (PLAS) and post-lipoprotein serum (PLPS) on the one hand and post-murein serum (PMS) on the other hand. Thus, with serial dilution the number of colonies induced decreased more rapidly in the case of PMS than in the case of PLAS or PLPS. At dilutions insufficient to induce any colony growth by themselves both PLAS and PLPS potentiated the growth of GM-CFC stimulated by semi-purified mouse lung-conditioned medium (MLCM), whereas PMS, like normal mouse serum (NMS), had no significant effect.

Molecular and biological properties of a macrophage colony-stimulating factor from mouse yolk sacs

A colony-stimulating factor (M-CSF) has been partially purified and concentrated from mouse yolk sac-conditioned medium (YSCM). M-CSF appeared to preferentially stimulate CBA bone marrow granulocyte-macrophage progenitor cells (GM-CFC) to differentiate to form macrophage colonies in semisolid agar cultures. By comparison, colony-stimulating factor (GM-CSF) from mouse lung-conditioned medium (MLCM) stimulated the formation of granulocytic, mixed granulocytic-macrophage, and pure macrophage colonies. Mixing experiments indicated that both M-CSF and GM-CSF stimulated all of the GM-CFC but that the smaller CFC were more sensitive to GM-CSF and that the larger CFC were more sensitive to M-CSF. Almost all developing "clones" stimulated initially with M-CSF continued to develop when transferred to cultures containing GM-CSF. In the converse situation, only 50% of GM-CSF prestimulated "clones" survived when transferred to cultures containing M-CSF. All clones initially stimulated by M-CSF or transferred to cultures stimulated by M-CSF contained macrophages after 7 days of culture. These results suggest that there is a population of cells (GM-CFC) that are capable of differentiating to form both granulocytes and macrophages, but, once these cells are activated by a specific CSF (e.g. M-CSF), they are committed to a particular differentiation pathway. The pattern of CFC differentiation was not directly related to the rate of proliferation: cultures maximally stimulated by M-CSF produced mostly macrophage colonies, but the presence of small amounts of GM-CSF produced granulocytic cells in 30% of the colonies. Gel filtration, polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, and affinity chromatography with concanavalin A-Sepharose indicated that M-CSF from yolk sacs was a glycoprotein with an apparent molecular weight of 60,000. There was some heterogeneity of the carbohydrate portion of the molecule as evidenced by chromatography on concanavalin A-Sepharose.

Preparation of colony stimulating activity from large batches of human urine and production of antisera against it

In vitro induction of myelopoetic colonies from mouse bone marrow has been used for measurement of leucopoetic colony stimulating activity (CSA) isolated from large batches of human urine. After high flow dialysis in artificial kidneys and immediate adsorption to DEAE-Cellulose, followed by purification on Con A-Sepharose, treatment with insoluble Papain and gelfiltration on Sephadex G 100, enrichment of CSA was about 6,000-fold. An important step of the enrichment procedure was the separation from a CSA-inhibiting protein, probably combining with CSA. Specific activity was further increased by preparative polyacrylamide gel electrophoresis to 5.3 X 10(6) units per mg protein. The total enrichment exceeded 25,000-fold. The final purification product consisted of a group of closely related proteins with high specific activity. Antisera raised with one of the electrophoretic fractions suppressed bioactivity in each of the different purification steps including the final CSA fractions differing in electrophoretic mobility. The antisera furthermore inhibited CSA in human lung and monocyte conditioned media but had only very little effect on partially purified CSA from stimulated human lymphocytes as well as CSA derived from mouse lung conditioned medium.

Changes in membrane-bound aminopeptidase on bone marrow-derived macrophages during their maturation in vitro

Myeloid colonies obtained by culturing mouse bone marrow cells with mouse lung conditioned medium were kept for up to 21 days in culture and the aminopeptidase content in single cells measured after staining with leucine 4-methoxy-2-naphthylamide. The enzyme was detectable only in mononuclear and not in granulocytic cells. The number of cells carrying the enzyme and the concentration of the enzyme in the mononuclear cells taken from whole dishes or single colonies increased remarkably but not uniformly from 7 days to maximal values at 13 days of culture, and then decreased again. The timing varied for individual colonies. Maximal enzyme concentrations were found in cells intermediate between the center and the fringe of a colony. However, most cells in a given colony showed concentration increases up to 13 days of culturing. During its life span in culture the mononuclear cell appears to gain aminopeptidase at the cell membrane and lose it again prior to death.