Recombinant human tumor necrosis factors alpha and beta stimulate fibroblasts to produce hemopoietic growth factors in vitro

The influences of TNF alpha and TNF beta were evaluated for their stimulatory and inhibitory effects on in vitro colony formation by human bone marrow granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells. Both TNF alpha and TNF beta induced fibroblasts to produce stimulators of CFU-GM, BFU-E, and CFU-GEMM in a dose-dependent fashion. Similar results were seen when equivalent concentrations of TNF alpha and TNF beta were used. Prior incubation of the TNF alpha and TNF beta with their respective antibodies inactivated the ability of the TNF preparations to induce the release of granulocyte-macrophage, erythroid, and multipotential colony-stimulating activity from fibroblasts. In addition, incubation of the TNF-induced fibroblast supernatant with antibody before colony assay resulted in enhanced colony formation, suggesting that the TNF carried over into the colony assay suppressed colony formation. Additional proof of this suppression by TNF was evident when TNF was added directly to the CFU-GM, BFU-E, and CFU-GEMM colony assays. IL-1 does not appear to function as an intermediary in growth factor production by fibroblasts stimulated with TNF because antibody to IL-1 displayed no effect. Furthermore, assay of TNF-induced fibroblast supernatant was negative for IL-1. These results suggest that TNF alpha and TNF beta exert both a positive and negative influence on in vitro hemopoietic colony formation.     

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)     

Characterization of reticulofibroblastoid colonies (CFU-RF) derived from bone marrow and long-term marrow culture monolayers

The maintenance of hemopoietic precursors in long-term liquid bone marrow cultures (LTBMC) is associated with the presence of an adherent stromal layer composed of heterogeneous cell populations. We have used a culture assay to promote the growth of one of its cellular components and characterize its properties. Freshly obtained bone marrow cells and cells derived from the adherent layer of LTBMC were grown in methylcellulose-clotted plasma in the presence of phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM), hydrocortisone (HC), and citrated normal human plasma. Both sources contained cells (CFU-RF) that gave rise to colonies of cells with a reticulofibroblastoid appearance. In the presence of HC, most colonies contained lipid-laden cells. Colonies could be further propagated as adherent layers when transferred into liquid cultures. These cells produced laminin, fibronectin, and collagen types I, III, IV, and V. They were negative for Von Willebrand factor VIII. The ability to synthesize laminin and collagen type IV distinguished these cells from a population of previously described bone marrow fibroblasts (CFU-F). The relationship of CFU-RF to hemopoietic precursors was investigated using patients with chronic myeloid leukemia and bone marrow transplant recipients. Cells within CFU-RF-derived colonies were uniformly negative for the Philadelphia chromosome, thus making it unlikely that they belonged to the malignant hemopoietic clone. CFU-RF-derived colonies in bone marrow transplant recipients were found to be exclusively of host origin. Both observations support the view that CFU-RF is not part of the repertoire of hemopoietic stem cells.     

Human thymic epithelial cells produce granulocyte and macrophage colony-stimulating factors

The development of culture conditions for growing normal human thymic epithelial (TE) cells free from contamination with other stromal cells has allowed us to identify and characterize TE cell-derived cytokines. In this study, we report that cultured human TE cells produced CSF that supported the growth of clonal hematopoietic progenitor cells in the light density fraction of human bone marrow cells. Thymic epithelial supernatants (TES) induced growth of granulocyte/macrophage colonies (CFU-GM), mixed granulocyte/erythrocyte/monocyte/megakaryocyte colonies (CFU-GEMM), and early burst-forming unit erythroid colonies (BFU-E). In addition, TES induced differentiation of the promyelocyte leukemic cell line HL-60 and stimulated growth of both granulocyte (CFU-G) and monocyte (CFU-M) colonies from murine bone marrow cells. Using anion exchange column chromatography, pluripotent CSF activities in TES were separated and shown to be distinct from an IL-1-like cytokine that has been shown as a TE cell-derived cytokine (TE-IL-1). Colony-stimulating activity supporting the growth of bone marrow CFU-GEMM, BFU-E, and CFU-GM co-eluted at 150 to 180 mM NaCl. A separate peak of CFU-GM-stimulating activity eluted early in the gradient at 20 mM NaCl. In Northern blot analysis of enriched RNA, synthetic oligonucleotide probes complementary to human G-CSF and M-CSF coding sequence each hybridized with a single RNA species of 1.7 and 4.4 kb, respectively. These data suggest that normal human TE cells synthesize G-CSF and M-CSF that promote differentiation of non-lymphoid hematopoietic cell precursors.     

Transforming growth factor-beta 1 enhances the suppression of human hematopoiesis by tumor necrosis factor-alpha or recombinant interferon-alpha

The effects of transforming growth factor-beta 1 (TGF-beta 1) on human hematopoiesis were evaluated in combination with two other regulatory cytokines, namely, recombinant human tumor necrosis factor-alpha (TNF-alpha) and recombinant human interferon-alpha (rIFN-alpha). Combinations of TNF-alpha and TGF-beta 1 resulted in a synergistic suppression of colony formation by erythroid progenitor cells (BFU-E) and an additive suppression of granulocyte-macrophage (CFU-GM) and multipotential (CFU-GEMM) progenitor cells. In addition, TGF-beta 1 synergized with rIFN-alpha to suppress CFU-GM formation, while the combined suppressive effects of both cytokines on CFU-GEMM and BFU-E were additive. When TGF-beta 1 was tested with TNF-alpha or IFN-alpha on granulocyte/macrophage colony-stimulating factor (GM-CSF)-stimulated bone marrow cells in a 5-day proliferation assay, the antiproliferative effects of TGF-beta 1 and TNF-alpha were additive, while those with TGF-beta 1 and rIFN-alpha were synergistic. A similar pattern was seen in the suppression of the myeloblastic cell line KG-1 where TGF-beta 1 in combination with TNF-alpha resulted in an additive suppression while inhibition by TGF-beta 1 and IFN-alpha was synergistic. These results demonstrate for the first time the cooperative effects between TGF-beta and TNF-alpha and IFN-alpha in the suppression of hematopoietic cell growth, raising the possibility that TGF-beta might be used in concert with TNF-alpha or IFN-alpha in the treatment of various myeloproliferative disorders.     

Water permeability of human hematopoietic stem cells

It is currently impossible to isolate or identify human hematopoietic progenitor cells from the bone marrow, yet the biophysical properties of these cells are important for the development of techniques to isolate and preserve stem cells for transplantation. Osmotic permeability properties of human bone marrow stem cells were estimated from the kinetics of cell damage in a hypotonic solution measured using in vitro colony assays for multipotential (CFU-GEMM) and committed (BFU-E, CFU-GM) progenitor cells. Cells exposed to a hypotonic solution swell as a result of water influx, and the rate of change of volume is proportional to the hydraulic conductivity of the plasma membrane. Cell damage occurs when the cell volume exceeds the maximum tolerable volume, so the hydraulic conductivity can be estimated from the kinetics of cell damage. For all the progenitor cells studied, the mean value of the hydraulic conductivity was 0.283 micron3/micron2/min/atm at 20 degrees C, with an Arrhenius activation energy of 6.41 kcal/mole. No significant differences were observed in the osmotic properties of the various progenitor cells. These data were used to predict the osmotic responses of human bone marrow stem cells at subzero temperatures during freezing.     

T-cell depletion of bone marrow does not inhibit in vitro hematopoiesis

One approach to overcome the problem of histoincompatibility in bone marrow transplantation is to use T cell depleted marrow from a haploidentical donor in an attempt to ameliorate graft-versus-host disease. Since the T cell requirements for normal hematopoiesis are uncertain, experiments were performed to study the effects of E rosette-T cell depletion on in vitro growth of hematopoietic progenitor cells. Marrow mononuclear cells were cultured in a modified CFU-GEMM assay before and after T cell depletion. The number of 7 day granulocytic and erythrocytic colonies, and 14 day granulocytic, erythrocytic and mixed colonies were enumerated and expressed in terms of colonies per 10(5) non T cells plated. T cell depletion did not result in decreased proliferation of any of these progenitors save possibly for 14 day granulocytic colonies in one of four experiments. In two cases, T cell depletion resulted in increased growth of progenitor cells. Three of four patients transplanted with T cell depleted haploidentical marrow cells engrafted. It is concluded that E rosette depletion of T cells from marrow does not decrease the potential of these cells to establish hematopoiesis in vitro or in vivo.     

Improved soft-agar colony assay in a fluid processing apparatus

Summary The standard method for quantitating bone marrow precursor cells has been to count the number of colony-forming units that form in semisolid (0.3%) agar. Recently we adapted this assay for use in hardware, the Fluid Processing Apparatus, that is flown in standard payload lockers of the space shuttle. When mouse or rat macrophage colony-forming units were measured with this hardware in ground-based assays, we found significantly more colony growth than that seen in standard plate assays. The improved growth correlates with increased agar thickness but also appears to be due to properties inherent to the Fluid Processing Apparatus. This paper describes an improved method for determining bone marrow macrophage precursor numbers in semisolid agar.     

Macrophage inflammatory protein (MIP)-1 beta abrogates the capacity of MIP-1 alpha to suppress myeloid progenitor cell growth

The effects of recombinant murine macrophage inflammatory protein (MIP)-1 beta and MIP-2 on the suppressive activity of MIP-1 alpha were tested using colony formation by human and murine bone marrow burst-forming unit-erythroid (BFU-E), colony-forming unit-granulocyte erythroid macrophage, megakaryocyte (CFU-GEMM), and colony-forming unit-granulocyte macrophage (CFU-GM) progenitor cells. MIP-1 beta, but not MIP-2, when added with MIP-1 alpha to cells, blocked the suppressive effects of MIP-1 alpha on both human and murine BFU-E, CFU-GEMM, and CFU-GM colony formation. Similar results were observed regardless of the early acting cytokines used: human rGM-CSF plus human rIL-3, and two recently described potent cytokines, a genetically engineered human rGM-CSF/IL-3 fusion protein and MGF, a c-kit ligand. The more potent the stimuli, the greater the suppressive activity noted. Pulse treatment of hu bone marrow cells with MIP-1 alpha at 4 degrees C for 1 h was as effective in inhibiting colony formation as continuous exposure of cells to MIP-1 alpha, and the pulsing effect with MIP-1 alpha could not be overcome by subsequent exposure of cells to MIP-1 beta. Also, pulse exposure of cells to MIP-1 beta blocked the activity of subsequently added MIP-1 alpha. For specificity, the action of a nonrelated myelosuppressive factor H-ferritin, was compared. MIP-1 alpha and H-ferritin were shown to act on similar target populations of early BFU-E, CFU-GEMM, and CFU-GM. MIP-1 beta did not block the suppressive activity of H-ferritin. Also, hemin and an inactive recombinant human H-ferritin mutein counteracted the suppressive effects of the wildtype H-ferritin molecule, but did not block the suppressive effects of MIP-1 alpha. These results show that MIP-1 beta's ability to block the action of MIP-1 alpha is specific. In addition, the results suggest that MIP-1 alpha and MIP-beta can, through rapid action, modulate early myeloid progenitor cell proliferation.     

Inhibition of early murine hemopoietic progenitor cell proliferation after in vivo locoregional administration of transforming growth factor-beta 1

Transforming growth factor-beta 1 (TGF beta 1) has been shown in vitro to be a potent negative regulator of growth and differentiation of early hemopoietic progenitor cells, but not of more mature progenitors. However, little information is yet available regarding similar effects in vivo. We have developed an approach whereby TGF beta 1 can be administered locoregionally to the bone marrow via direct injection into the femoral artery. Our studies show that intrafemoral administration of a single bolus dose of TGF beta 1 potently inhibits the baseline and IL-3-driven proliferation of bone marrow cells. This inhibition is relatively selective for the earlier multipotential granulocyte, erythroid, megakaryocyte, and macrophage CFU progenitor cells since these are completely inhibited while the more differentiated CFU assayed in culture colonies are inhibited by about 50%. The inhibition of hemopoietic progenitor growth and differentiation is both time and dose dependent with the maximal effect on the marrow observed at 24 h with doses greater than or equal to 5 micrograms/mouse, and the effect is reversed at later times. A possible practical implication of these in vivo results could be the use of TGF beta 1 to protect stem cells in the bone marrow from the myelotoxic effects of chemotherapeutic drugs.     

Improvement of culture conditions for human megakaryocytic and pluripotent progenitor cells by low oxygen tension

The effect of low oxygen tension on the growth of human hemopoietic progenitor cells in bone marrow was investigated using the semisolid methylcellulose colony assay. The clonal growth of granulocyte-macrophage progenitors (CFU-gm), early (BFU-e) and late (CFU-e) erythroid progenitors, megakaryocyte progenitors (CFU-meg) and pluripotent progenitors (CFU-mix) improved more markedly incubation at the low oxygen tension (5%) than in conventional air (20%). The thiol compound 2-mercaptoethanol had a strong additive effect on colony growth in conventional air, but little or no effect in the low oxygen tension. These results suggest that enhancement of colony growth in the low oxygen tension may be due to a decrease in the production of oxygen intermediates.     

Proliferation activity of stromal stem cells (CFU-f) from hemopoietic organs of pre- and postnatal mice

Stromal stem cells (CFU-f assay) from hemopoietic organs of fetuses, in contrast to adult animals, exhibit a high proliferation activity. This implies that these CFU-f are radiosensitive and potential target cells after radioactive contamination of fetuses. Furthermore, the percentage of CFU-f in DNA synthesis is correlated with the hemopoietic activity in liver, spleen, and bone marrow. As hemopoiesis starts, high numbers of CFU-f are in S phase. In fetal liver, spleen, and bone marrow, values of 70, 43, and 58%, respectively, are reached. As hemopoietic activity decreases in liver and stabilizes in spleen and bone marrow, mitotic activity of these stromal stem cells becomes undetectable.     

Separation of immunoreactive lymphocytes from human pluripotent stem cells (CFU-GEMM) by means of counterflow centrifugation

Counterflow centrifugation with continuous monitoring of the output for cell number and cell scatter was used to separate low density (d less than 1.070 g/ml) human bone marrow cells in two fractions: one containing the majority of small size lymphocytes and the other the majority of the larger sized committed progenitor cells. The recovery of the pluripotent stem cells (CFU-GEMM) in the large cell fraction was complete. The mitogenic reactivity of this putative stem cell fraction had decreased to 6% and 11%, of the original value as measured with phytohemagglutinin stimulation and one way mixed lymphocytic culture respectively. Counterflow centrifugation offers a physical separation technique, by which the majority of the immunoreactive cells can be separated from the pluripotent hematopoietic stem cells.     

造血细胞活力冷冻损伤的可恢复性

人骨髓冻存后其造血祖细胞活力有一定程度下降,本研究对这种下降的可逆性作了初步观察。结果发现,用双层法和单层法作CFU-GM培养时,未冻存骨髓集落产率相近,冻存骨髓双层法的CFU-GM产率高于单层法。骨髓细胞用20％FM-CM、PHA-LYCM、PHA-PMCM预孵育2h后,分别测定其CFU-GM、BFU-E与CFU-Mix,发现这种孵育过程对未冻存骨髓的集落产率无明显影响,而冻存骨髓的集落产率在孵育后可升高(GEMmeg除外)。说明骨髓造血祖细胞对冻存的损伤反应不均一,部分受损细胞在一定条件下可以恢复其增殖活力。这对于用冻存骨髓作骨髓移植可能有一定意义。     

Release of hemopoietic factors by normal human T cell lines with either suppressor or helper activity

We analyzed the release of activities capable of stimulating the in vitro growth of human hemopoietic progenitor cells by long-term cultured T cell growth factor (TCGF)-dependent human T lymphocytes. Seven cell lines tested produced colony-stimulating activity (CSA) as well as burst-promoting activity (BPA). The CSA stimulated primarily the growth of the cells forming colonies after 14 days of incubation. In addition the supernatants from these seven T-cell lines showed the ability to induce the in vitro growth of mixed granulocyte, erythroid, megakaryocyte, macrophage colonies (CFU-GEMM). The release of hemopoietic factors did not depend on the presence of accessory cells or phytohemagglutinin or serum during the incubation for factor production. In six of the T cell lines the majority of the cells were reactive to the OKT 8 monoclonal antibody (MoAb), whereas one cell line contained mostly OKT 4+ cells. Suppressor activity was detected in three tested OKT 8+ cell lines, while the one OKT 4+ displayed helper activity. All cell lines produced hemopoietic factors with equal efficiency. These results indicate that factors affecting human hematopoiesis are produced by normal T lymphocytes in long-term culture and this property is not related to the helper or suppressor activity of the cultured cells.     

Effects of recombinant human tumor necrosis factor (rhTNF) on normal human and mouse hemopoietic progenitor cells

We examined the effects of recombinant human tumor necrosis factor (rhTNF) on normal human and murine granulocyte-macrophage (CFU-gm) and erythroid (CFU-e, BFU-e) progenitor cells. We suppressed in vitro colony formation by human marrow CFU-gm, CFU-e and BFU-e or peripheral blood BFU-e by adding rhTNF to the culture in a dose-related manner. A half-maximal inhibition was observed with 1-10 ng/ml. Leukemic cell line K562 cells were found to be sensitive to rhTNF in the clonogenic colony assay. However, the clonal growth of murine marrow CFU-e and BFU-e colonies was less than 50% inhibited and CFU-gm growth was unaffected even at a concentration of 1,000 ng/ml. We observed slight to moderate inhibition after 24 h pulse exposure of both human and murine-committed progenitors to rhTNF prior to the culture. Intravenous injection of 1 mg/kg of rhTNF caused a marked decrease in marrow erythroid progenitors and consequently caused anemia in the mice. Our data indicate that rhTNF has a suppressive effect on normal human and murine hemopoietic colony formation in vitro and murine erythropoiesis in vivo.     

Transplantation of hematopoietic stem cells from the peripheral blood

Hematopoietic stem cells can be collected from the peripheral blood. These hematopoietic stem cells (HSC), or better progenitor cells, are mostly expressed as the percentage of cells than react with CD34 antibodies or that form colonies in semi-solid medium (CFU-GM). Under steady-state conditions the number of HSC is much lower in peripheral blood than in bone marrow. Mobilization with chemotherapy and/or growth factors may lead to a concentration of HSC in the peripheral blood that equals or exceeds the concentration in bone marrow. Transplantation of HSC from the peripheral blood results in faster hematologic recovery than HSC from bone marrow. This decreases the risk of infection and the need for blood-product support. For autologous stem-cell transplantation (SCT), the use of peripheral blood cells has completely replaced the use of bone marrow. For allogeneic SCT, on the other hand, the situation is more complex. Since peripheral blood contains more T-lymphocytes than bone marow, the use of HSC from the peripheral blood increases the risk of graft-versus-host disease after allogeneic SCT. For patients with goodrisk leukemia, bone marrow is still preferred, but for patients with high-risk disease, peripheral blood SCT has become the therapy of choice.     

IL-4 regulates c-kit proto-oncogene product expression in human mast and myeloid progenitor cells.

The c-kit proto-oncogene encodes the receptor for a novel hemopoietic cytokine, termed stem cell factor (SCF) or mast cell growth factor (MGF) according to its stimulating spectrum. The human receptor for SCF/MGF is expressed in a subset of normal bone marrow progenitor cells, in leukemic myeloid cells, and in mast cells. In the present study, the effects of recombinant human growth regulators (IL-1 through -9, granulocyte-macrophage/granulocyte/macrophage-CSF, IFN, and TNF) on c-kit proto-oncogene product expression were analyzed by indirect immunofluorescence, by using the anti-SCF/MGFR mAb YB5.B8, and Northern blot analyses, by using a c-kit oligonucleotide probe. Of all cytokines tested, IL-4 was found to down-regulate expression of YB5.B8 Ag in the human mast cell line HMC-1 (maximum inhibition, 51.05 +/- 16.36% mean fluorescence intensity of control; p less than 0.02), as well as in primary leukemic myeloid cells. IL-4 was also found to down-regulate expression of YB5.B8 Ag in normal enriched bone marrow progenitor cells. The effects of IL-4 on expression of YB8.B8 Ag in myeloid/mast cell progenitors was dose and time dependent (maximum effects observed on days 2 and/or 4, by using 50 U/ml of rIL-4) and could be neutralized by using anti-IL-4 mAb. Moreover, IL-4 was found to down-regulate expression of c-kit mRNA in leukemic myeloid cells as well as in HMC-1 cells. Together, these observations identify IL-4 as a regulator of c-kit proto-oncogene product expression in the human system. The effects of IL-4 on human hemopoietic progenitor cells and mast cells may be mediated in part through regulation of SCF/MGFR expression.     

In vitro inhibition of hemopoietic cell line growth by hepatitis B virus.

The effects of hepatitis B virus (HBV) on established human cell lines of various tissue origins were evaluated by clonal or colorimetric assays in methylcellulose culture. HBV exposure inhibited the growth of six hemopoietic cell lines, while similar incubation did not affect the growth of seven nonhemopoietic carcinoma cell lines of breast, colon, liver, and stomach origin. The inhibition of hemopoietic cell line colony formation was dependent on the presence of intact viral (Dane) particles and the ratio of exposure of virions to cells and was reversible with antibodies to pre-S1, pre-S2, and S envelope protein epitopes. Purified HBV DNA, surface antigen pre-S antigens, and core antigen did not inhibit cell line growth. These results further demonstrate the tropism of HBV for cells of hemopoietic origin, confirming our previous findings on the effects of HBV on the growth of normal bone marrow progenitor cells in vitro. Established human tissue culture cell lines may be used to study the interactions of hemopoietic cells with HBV.     

Transforming growth factor beta: possible roles in the regulation of normal and leukemic hematopoietic cell growth

We have recently demonstrated that transforming growth factor (TGF)-beta 1 and TGF-beta 2 are potent inhibitors of the growth and differentiation of murine and human hematopoietic cells. The proliferation of primary unfractionated murine bone marrow by interleukin-3 (IL-3) and human bone marrow by IL-3 or granulocyte/macrophage colony-stimulating factor (GM-CSF) was inhibited by TGF-beta 1 and TGF-beta 2, while the proliferation of murine bone marrow by GM-CSF or murine and human marrow with G-CSF was not inhibited. Mouse and human hematopoietic colony formation was differentially affected by TGF-beta 1. In particular, CFU-GM, CFU-GEMM, BFU-E, and HPP-CFC, the most immature colonies, were inhibited by TGF-beta 1, whereas the more differentiated unipotent CFU-G, CFU-M, and CFU-E were not affected. TGF-beta 1 inhibited IL-3-induced growth of murine leukemic cell lines within 24 h, after which the cells were still viable. Subsequent removal of the TGF-beta 1 results in the resumption of normal growth. TGF-beta 1 inhibited the growth of factor-dependent NFS-60 cells in a dose-dependent manner in response to IL-3, GM-CSF, G-CSF, CSF-1, IL-4, or IL-6. TGF-beta 1 inhibited the growth of a variety of murine and human myeloid leukemias, while erythroid and macrophage leukemias were insensitive. Lymphoid leukemias, whose normal cellular counterparts were markedly inhibited by TGF-beta, were also resistant to TGF-beta 1 inhibition. These leukemic cells have no detectable TGF-beta 1 receptors on their cell surface. Last, TGF-beta 1 directly inhibited the growth of isolated Thy-1-positive progenitor cells. Thus, TGF-beta may be an important modulator of normal and leukemic hematopoietic cell growth.