Efficacy of intensive, high-dose anthracycline-based therapy in intermediate- and high-grade non-Hodgkin's lymphomas.
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Antibiotics, Antineoplastic↗
Biomedical subjects
K S Zuckerman
Publications and source records attributed to K S Zuckerman.
Chemotherapy of intermediate- and high-grade non-Hodgkin's lymphomas with an intensive epirubicin-containing regimen.
An intensive chemotherapy regimen (EVDAC), including high-dose epirubicin, vincristine, and dexamethasone followed by cyclophosphamide and high-dose cytarabine, was administered to 54 untreated adults with intermediate or high-grade non-Hodgkin's lymphomas (NHL). The median age was 59, 61% were Ann Arbor Stage IV, 57% had "B" symptoms, 50% had serum lactate dehydrogenase greater than 250 U/L, and 48% had masses greater than 7 cm (33% > 10 cm) in diameter. Seventy-six percent of patients attained complete or probable complete remissions. The Kaplan-Meier actuarial failure-free survival at 7 years is 50%, and 59% (32 of 54) of all patients started on therapy remain alive and in first remission at a median of 62+ (range, 49+ to 76+) months from completion of therapy. Nearly all patients developed severe neutropenia. Febrile episodes requiring hospitalization during neutropenia occurred after 56% of courses of epirubicin, vincristine, and dexamethasone and after 9% of courses of cyclophosphamide and cytarabine; 80% of patients were hospitalized at least once. Platelet count nadirs of less than 20,000/microL occurred after only 1 of 146 evaluable courses of epirubicin and after none of the cyclophosphamide/cytarabine courses. Although 8 patients had decreases of at least 0.12 in their left ventricular ejection fractions (5 to below normal levels), none have developed clinically evident congestive heart failure. Clinically significant mucositis occurred after only 8% of courses of high-dose epirubicin. Three deaths from infections and one from hyperkalemia with cardiac arrest occurred during therapy. These results confirm that high remission and sustained, failure-free survival rates can be achieved in patients with aggressive NHL, using high-dose anthracycline-containing chemotherapy regimens. Epirubicin appears to have an advantage over doxorubicin at high doses because of decreased toxicity at a therapeutically equivalent dose. These phase II study results need to be validated in a randomized phase III trial, and growth factors should be used to attempt to reduce the neutropenia-associated complications.
Adult↗
Transplantation of umbilical cord blood after myeloablative therapy: analysis of engraftment.
The possibility that umbilical cord and placental blood from an HLA-identical sibling might produce stable donor-derived lymphohematopoietic engraftment was tested in a patient with juvenile chronic myelogenous leukemia (JCML). After conditioning with high-dose busulfan and cyclophosphamide, cryopreserved umbilical cord blood, containing 0.5 x 10(8) nucleated cells/kg and 2.7 x 10(4) colony forming units-granulocyte, macrophage (CFU-GM)/kg, was infused. A leukocyte count greater than 1,000/microL, absolute neutrophil count (ANC) greater than 500/microL, and platelet count greater than 20,000/microL (untransfused) were observed on days 39, 39, and 47 after transplantation, respectively. Donor cell engraftment was documented in the peripheral blood and bone marrow by cytogenetic analysis, restriction fragment length polymorphism (RFLP), and polymerase chain reaction (PCR) as early as day 21. Furthermore, the donor origin of each lymphohematopoietic lineage (ie, CD5+ T cells, CD19/20+ B cells, CFU-GM, and burst-forming unit-erythrocyte [BFU-E]) was confirmed. On day 200, assays of the peripheral blood and bone marrow showed an abnormal proliferation of CFU-GM at low seeding densities in the absence of exogenous growth factors, as well as a hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF), both pathophysiologic characteristics of JCML. Recurrent disease was confirmed histologically on day 225. Together, these results demonstrate that umbilical cord blood contains sufficient numbers of hematopoietic stem cells necessary for the engraftment of leukemia patients treated with myeloablative therapy and that the detection of "spontaneous" CFU-GM and hypersensitivity to GM-CSF after treatment is a marker of residual or recurrent disease in patients with JCML.
Base Sequence↗
Selective hypersensitivity to granulocyte-macrophage colony-stimulating factor by juvenile chronic myeloid leukemia hematopoietic progenitors.
Juvenile chronic myelogenous leukemia (JCML) is a good model for the study of myeloproliferation because JCML hematopoietic progenitor cells grow in vitro at very low cell densities without the addition of exogenous stimulus. Previous studies have demonstrated that this proliferation is dependent on granulocyte-macrophage colony-stimulating factor (GM-CSF), and that removal of monocytes from the cell population before culture eliminates this "spontaneous" myeloproliferation, suggesting a paracrine role of monocyte stimulation. However, subsequent studies have shown that increased GM-CSF production from the JCML monocytes is not a consistent finding and therefore not a plausible sole mechanism. In examining hematopoietic growth factor dose-response curves, both JCML GM and erythroid nonadherent progenitor cell populations displayed a marked and selective hypersensitivity to GM-CSF. Responses to interleukin-3 and G-CSF were identical to control dose-response curves. This is the first demonstration of a myeloid leukemia in which hypersensitivity to a specific growth factor appears to be involved in the pathogenesis of the disease.
Cell Division↗
The role of monocyte-derived hemopoietic growth factors in the regulation of myeloproliferation in juvenile chronic myelogenous leukemia.
Juvenile chronic myelogenous leukemia (JCML) is a rare pediatric malignancy characterized by marked hepatosplenomegaly, leukocytosis with prominent monocytosis, elevated fetal hemoglobin, no Philadelphia chromosome, and generally a poor prognosis. In vitro, JCML peripheral blood granulocyte-macrophage progenitors (granulocyte-macrophage colony-forming units, CFU-GM) demonstrate the unique characteristic of "spontaneous" proliferation at very low cell densities in the absence of exogenous growth factors. The "spontaneous" CFU-GM proliferation can be abolished by prior adherent cell (monocyte) depletion, suggesting a paracrine mode of cellular proliferation. Although previous studies using a [3H]thymidine ([3H]TdR) incorporation assay suggested an important role for granulocyte-macrophage colony-stimulating factor (GM-CSF) in JCML, many non-growth factor-related reasons for [3H]TdR incorporation and the relatively low level of inhibition of [3H]TdR uptake left those conclusions open to question. Therefore, we performed clonal CFU-GM assays, which more specifically reflect cytokine effects on CFU-GM, using JCML peripheral blood mononuclear cells (PBMNC) and neutralizing antibodies against GM-CSF, granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating (M-CSF), interleukin 3 (IL-3), interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), interleukin 4 (IL-4), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF alpha), and interferon gamma (IFN gamma). Cultures containing anti-GM-CSF alone inhibited "spontaneous" JCML CFU-GM by 87% +/- 9% (mean +/- standard error of the mean [SEM]). No other anti-cytokine antibody produced a significant inhibition of CFU-GM growth. Various combinations of antibodies, excluding anti-GM-CSF, failed to demonstrate any synergistic inhibitory effects upon CFU-GM. Because this apparent paracrine cellular stimulation could be due to excessive cytokine production, by monocytes or other accessory cells, we examined cytokine levels in conditioned media from various JCML cell populations using enzyme-linked immunosorbent assays (ELISAs). Monocytes from only a minority of JCML patients produced higher than normal quantities of GM-CSF, G-CSF, IL-1 beta, IL-6, and/or TNF alpha, but no obvious pattern could be discerned. Further, only 7 of 15 JCML monocyte-conditioned media (MCM) had elevated GM-CSF, and 6 of 15 JCML patients had normal levels of all nine cytokines tested. The monocyte depletion experiments and the inhibition experiments with anti-cytokine antibodies taken together demonstrate clearly that the "spontaneous" growth of JCML CFU-GM in vitro critically depends on at least one monocyte-derived growth factor, GM-CSF.(ABSTRACT TRUNCATED AT 400 WORDS)
Antibodies↗
Valproic acid-induced cytopenias: evidence for a dose-related suppression of hematopoiesis.
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Adolescent↗
Specific inhibition of interleukin 3 bioactivity by a monoclonal antibody reactive with hematopoietic progenitor cells.
HIM1, originally designated HI98, a murine monoclonal IgM antibody raised against human mononuclear cells, has been reported at the Fourth International Leukocyte Typing Workshop (called antibody M0141) to be the only one of 157 antibodies tested that inhibited binding of interleukin 3 (IL-3) to KG-1 human acute myelogenous leukemia cells and normal human monocytes. We have carried out detailed studies of the selective effect of HIM1 on IL-3-mediated stimulation of hematopoietic progenitors. Preincubation of normal human bone marrow mononuclear cells, depleted of adherent cells and T cells, with HIM1 antibody resulted in a dose-dependent inhibition of IL-3-mediated stimulation of both erythroid burst-forming units (maximum inhibition 55%) and granulocyte/macrophage colony-forming units (maximum inhibition 49%). HIM1 antibody had no effect on growth of erythroid colony-forming units in culture. In addition, preincubation of the cells with HIM1 antibody had no deleterious effect on granulocyte/macrophage colony-stimulating factor-induced growth of either erythroid bursts or granulocyte/macrophage colonies. To be certain that the HIM1 antibody did not react directly with IL-3 itself, we attempted to use immunodepletion to remove IL-3 that had been added to our culture medium. Although we were able to remove IL-3 bioactivity by immunodepletion with anti-IL-3 antibody bound to Sepharose beads, beads with attached HIM1 did not remove IL-3 activity from the medium. Polymorphonuclear neutrophils bind high levels of HIM1, although they have very few or no detectable IL-3 receptors. Therefore, this antibody appears to recognize a cell surface antigen that is critical for optimal IL-3 binding and bioactivity but is not the actual IL-3 receptor.
Antibodies, Monoclonal↗
Chemotherapy of intermediate- and high-grade non-Hodgkin's lymphomas with a high-dose doxorubicin-containing regimen.
Forty-seven previously untreated patients with intermediate- or high-grade non-Hodgkin's lymphoma were treated with four courses of a regimen that consisted of high-dose (120 mg/m2) Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), vincristine (2 mg), cytarabine (3 gm/m2), and dexamethasone (50 mg intravenously [IV] on day 1 and 20 mg/day orally on days 2 to 5) (AVAD), which was administered every 3 to 4 weeks. The median age of the patients was 58 years; 72% were Ann Arbor stage IV, 49% had "B" symptoms, 62% had masses larger than 7 cm, 40% had masses at least 10 cm in diameter, and 49% had serum lactate dehydrogenase (LDH) greater than 250 U/L. Overall, 72% of the patients (89% of diffuse large-cell lymphoma [DLCL] patients) attained complete (CR) or probable complete responses (PCR), and relapses occurred in 32%. There were no episodes of clinical congestive heart failure, but one patient developed recurrent ventricular arrhythmias. Fever during neutropenia occurred with 65% of treatment courses. Three deaths were attributed primarily to complications of therapy. The lymphoma-free survival of all entered patients is 51% (24 of 47), with a follow-up of 30 to 67 months (median, 58 months). These results confirm that high CR/PCR and long-term survival rates can be achieved in patients with aggressive histologies of non-Hodgkin's lymphomas, even in groups with poor prognostic factors, using high-dose anthracycline-containing chemotherapy regimens delivered over a short period of time. However, the apparently higher relapse rate in comparison to our previous study leads us to speculate that consolidation with noncross-resistant agents may be helpful in increasing even further the cure rate in this group of patients.
Adult↗
Granulocyte-macrophage colony-stimulating factor is an endogenous regulator of cell proliferation in juvenile chronic myelogenous leukemia.
Juvenile chronic myelogenous leukemia (JCML) is a rare myeloproliferative disorder of early childhood that is clinically and cytogenically distinct from the well-recognized adult type of chronic myeloid leukemia. Unlike the adult disease, growth of hematopoietic progenitors from peripheral blood (PB) occurs in the absence of exogenous stimulus even at low cell densities. This so-called "spontaneous" growth can be abrogated by adherent cell depletion and appears to depend on production of endogenous growth factors. We studied seven children with JCML to determine the nature of endogenous stimulators. With isolated PB mononuclear cells (PBMNCs) and a 3H-thymidine (3H-TdR) incorporation assay, JCML cells were shown to incorporate high levels of 3H-TdR when cultured in the absence of stimulus even at low cell densities. When neutralizing antisera prepared against each of the four known colony-stimulating factors (CSFs), GM-CSF, G-CSF, M-CSF, and interleukin-3 (IL-3), as well as antisera against interleukin-1 (alpha and beta) and tumor necrosis factor (TNF) were added to these cultures, only the antisera against recombinant human GM-CSF (rhGM-CSF) consistently resulted in significant inhibition of cell proliferation, achieving up to 72% inhibition of 3H-TdR incorporation in one case. Monoclonal antibodies (MoAbs) against rhGM-CSF resulted in a similar and highly significant degree of inhibition. A marked inhibitory effect of rhGM-CSF antiserum on "spontaneous" growth of PB CFU-GM derived colonies in semisolid medium was also demonstrated in four of five patients studied (87% to 90% inhibition). Production of growth factors by highly enriched JCML monocytes was variable. When initially studied in five of the seven patients, the monocytes from three of the patients revealed increased release of IL-1-like activities; two patients had levels similar to those of controls. One patient with normal levels when initially studied was later shown to have markedly increased amounts of IL-1-like activities in a second preparation of monocyte-conditioned medium (MCM). High levels of GM-CSF were detected in the initial MCM from one patient, but this may have indirectly reflected elevated IL-1-like activities present in the MCM. IL-3 and M-CSF levels were either low or undetectable in the patients studied as compared with MCM prepared with normal adult monocytes. These results clearly implicate GM-CSF as the primary endogenous regulator of JCML cell proliferation in culture and suggest that this malignant myeloproliferative disease may in part result from paracrine stimulation of marrow progenitor cells by growth factors/cytokines secreted by the malignant monocytes.
Bone Marrow↗
The t complex polypeptide 1 (TCP-1) is associated with the cytoplasmic aspect of Golgi membranes.
The t complex polypeptide 1 (TCP-1) is a protein of unknown function expressed in large amounts during spermatogenesis. Rat monoclonal antibodies recognizing TCP-1 have been prepared and used to immunoprecipitate and Western blot a 57 kd protein from germ cell and tissue culture cell extracts. In tissue culture cells, indirect immunofluorescent localization of antigen indicated a perinuclear distribution similar to that of the Golgi apparatus. Analysis of the TCP-1 distribution in tissue culture cells showed that the polypeptide was associated with the cytoplasmic aspect of membranes of the trans-Golgi network (TGN). The distribution in spermatids suggested that TCP-1 was localized to structures often associated with the developing acrosome. The TCP-1 antigenic epitopes are highly conserved, allowing the protein to be identified in cells across a wide variety of vertebrate species and tissues. These experiments suggest that TCP-1 may be essential for transport of proteins through the exocytic pathway in all cells and required in large amounts for acrosome formation in developing spermatids.
Acrosome↗
Spontaneous growth of colonies with mature T lineage phenotype from T-cell-depleted bone marrow precursors in a patient with a lymphoproliferative disorder of the large granular lymphocytes.
Bone marrow cells from a patient with pancytopenia and a lymphoproliferative disorder of large granular lymphocytes (LGL) were cultured and tested for their hemopoietic colony-forming potential. Neither erythroid nor granulocyte-macrophage colony formation could be obtained from unfractionated, or LGL-depleted bone marrow cell preparations. However, a spontaneous growth of lymphoid colonies was observed after culturing LGL-depleted (T3-) bone marrow cell suspensions for 25 days. Pooled colonies expanded with recombinant interleukin-2 yielded a population composed predominantly of mature T cells (T3+, Leu 6-). These findings suggest that some (T3-) T cell precursors may mature in the bone marrow and that, in our patient, LGL may have exerted a suppressor effect on this maturational process.
Aged↗
Establishment of Tac-negative, interleukin-2-dependent cytotoxic cell lines from large granular lymphocytes (LGL) of patients with expanded LGL populations.
Cell lines were established from purified large granular lymphocytes (LGL) isolated from the peripheral blood of seven patients with phenotypically homogeneous LGL expansions. LGL were stimulated with phytohemagglutinin (PHA) or recombinant interleukin-2 (rIL-2) and further expanded in vitro in IL-2-containing media. The surface phenotype of LGL, as assessed by monoclonal antibody staining, was T3+ T8+ in five patients, T3- T8- in one, and T3+ T8- in another patient. The cells also expressed Leu 7, Leu 11, and/or OKM 1 markers in various proportions and were identifiable as LGL by their morphological and cytochemical features. The original surface phenotype of the unstimulated LGL was retained in the IL-2-dependent cell lines from each individual patient, i.e., T3+ T8+ cells originated T3+ T8+ cell lines and T3- T8- cells originated T3- T8- cell lines. Other markers, such as Leu 11 and OKM 1, were generally lost in culture. LGL proliferated in response to rIL-2 but did not express detectable IL-2 receptors, even after prolonged periods of culture. All cell lines from each individual patient had the same surface phenotype, and within the single lines, all of the cells expressed the same markers. Cell lines from two patients consistently displayed chromosomal abnormalities. Although different in the two patients, the abnormalities were identical in all of the lines from the same patient and detectable in most of the cells examined, suggesting a clonal origin for the abnormally expanded LGL populations. Freshly isolated LGL did not exert NK activity. However, the IL-2-dependent LGL lines acquired the ability to kill K562 target cells and to produce gamma interferon (gamma-IFN). No direct correlation was observed between these two properties.
Antigens, Surface↗
Resistance of the stromal cell in murine long-term bone marrow cultures to damage by ionizing radiation.
The ability of bone marrow stromal cells to survive and function after exposure to ionizing radiation remains controversial. Therefore, we used the murine long-term bone marrow culture system to analyze the effects of single doses of ionizing radiation (9-500 Gy) on the function of a preexisting, nearly confluent stroma that was supportive of hematopoiesis. Hematopoiesis ceased promptly in all the irradiated cultures and did not recover unless fresh marrow cells were inoculated. Radiation doses less than or equal to 100 Gy caused no obvious morphologic change in the cells. Total RNA, total protein, and collagen synthesis declined by 35%-60% within two days after even 9 Gy; but radiation doses up to 100 Gy caused minimal or no additional decline. Although RNA synthesis recovered nearly to normal within three weeks after radiation doses less than 100 Gy, total protein and collagen synthesis remained suppressed. Normal adherent layers irradiated with 9-50 Gy supported long-term hematopoiesis by fresh Sl/Sld marrow cells, although Sl/Sld marrow did not demonstrate sustained hematopoiesis when cultured in plain culture dishes or over normal stroma irradiated with 200 Gy. Thus, bone marrow stromal cells in long-term cultures did not show evidence of substantial cell death over at least the six-week period studied after irradiation with as much as 100 Gy, and they maintained hematopoietic supportive functions when irradiated with up to at least 50 Gy.
Animals↗
Production of erythroid burst-promoting activity (BPA) and granulocyte-monocyte colony-stimulating activity (GM-CSA) by isolated human T-lymphocyte subpopulations.
T-lymphocytes and monocytes are prominent among the classes of normal human cells that have been implicated in the production of the hemopoietic growth factors granulocyte-macrophage colony-stimulating activity (GM-CSA) and erythroid burst-promoting activity (BPA). To investigate the nature of the cooperativity that occurs during the elaboration of these growth factors by activated T-lymphocytes and monocytes in vitro, and to define the subsets of T cells involved in this response, we studied the production of GM-CSA and BPA by populations of T-lymphocytes isolated by fluorescence-activated cell sorting, using the monoclonal antibodies OKT3, OKT4, and OKT8. When OKT3+, OKT4+, or OKT8+ cells were incubated for five days in liquid suspension cultures, their production of GM-CSA and BPA was undetectably low. When 5% autologous monocytes were added to the cultures, no increase in the secretion of either of these classes of growth factors was noted. In the presence of concanavalin A (Con A), measurable quantities of both GM-CSA and BPA were elaborated by all three populations of T cells in the absence of monocytes; however, when autologous monocytes were added to the Con A-stimulated T cells, the secretion of both GM-CSA and BPA was markedly enhanced. In addition, we found that supernates of unfractionated T cells incubated with Con A contained not only GM-CSA and BPA but also a potent inhibitor(s) of BPA that could be demonstrated by dilution of the media and removed by gel filtration. In contrast, no inhibitor of GM-CSA was found. By molecular sieve chromatography of the supernates, GM-CSA and BPA coeluted as a single peak. However, the two biologic activities could be separated on the basis of heat stability, since GM-CSA proved to be heat labile whereas BPA did not. Our data indicate that GM-CSA and BPA derived from human T cells are similar in their apparent molecular weights and in the pattern of their production in suspension cultures in response to lectin stimulation. The secretion of both GM-CSA and BPA by Con A-stimulated T cells is facilitated by the presence of autologous monocytes, and is not restricted to either the OKT4- or the OKT8-defined subset.
Antibodies, Monoclonal↗
Production of multilineage hemopoietic growth-stimulating activities by a human melanoma cell line.
In this study, we report that conditioned medium (CM) from the human melanoma cell line Hs0294 contains growth-stimulating activity for human and murine hemopoietic progenitor cells of multiple lineages. Crude CM was assayed for hemopoietic progenitor cell growth-stimulating activity (HP-GSA) in plasma clot cultures of 10(5) C57B1/6J mouse bone marrow cells or 10(5) light-density, nonadherent human peripheral blood mononuclear cells. CM concentrations as low as 0.2% had demonstrable HP-GSA for murine and human hemopoietic progenitor cells, although peak activity for all hemopoietic progenitor cell types assayed (murine CFU-Mix, BFU-E, CFU-GM, and CFU-M and human BFU-E) was observed with 5%-10% Hs0294-CM. Growth-stimulating activity for human erythroid progenitors (BFU-E) was comparable to that produced by phytohemagglutinin-stimulated human mononuclear cell CM. Stimulation of murine hemopoietic progenitors by Hs0294-CM was comparable to the activity in pokeweed mitogen-stimulated mouse spleen cell CM. The Hs0294-CM did not contain detectable quantities of erythropoietin or interleukin 3. Human burst-promoting activity was stable through sequential freezing and thawing, heating to 50 degrees C for 1 h or 100 degrees C for 5 min, and incubation at pH 9.8 for 1 h, but lost 70% of its activity when incubated at pH 2.2 for 1 h. More than 95% of the HP-GSA was recovered in the 50%-80% fraction by (NH4)2SO4 precipitation. The HP-GSA had an estimated molecular weight of approximately 21,000. In conclusion, we have shown that a human melanoma cell line, Hs0294, produces multilineage HP-GSA.
Animals↗
Monocytes stimulate fibroblastoid bone marrow stromal cells to produce multilineage hematopoietic growth factors.
In previous studies we have found that monocytes produce soluble factors that stimulate human umbilical vein endothelial cells to produce granulocyte-macrophage colony-stimulating activity (CSA), burst-promoting activity (BPA), and megakaryocyte colony-stimulating activity (Meg-CSA) as well as factors that stimulate T lymphocytes and neonatal fibroblasts to produce CSA. To test the hypothesis that monocytes would similarly stimulate the production of hematopoietic growth factors by autologous bone marrow stromal cells, multiply-passaged adherent fibroblastoid cells derived from the bone marrow of normal volunteers were exposed to conditioned media prepared by incubating autologous peripheral blood monocytes in complete medium for three days. When conditioned media from stromal cells incubated in monocyte-conditioned medium were compared with those of stromal cells cultured in the absence of monocyte-conditioned medium, BPA was increased fourfold and CSA was increased more than 30-fold. We conclude that mononuclear phagocytes recruit stromal cells of the marrow to produce multilineage growth factors in vitro. We suggest that these monocyte-derived recruiting activities may play an important role in orchestration of hematopoietic growth factor production by cells of the marrow microenvironment.
Bone Marrow Cells↗
Sl/Sld mouse bone marrow stroma in vitro contains an active radiation-sensitive inhibitor of normal hemopoiesis.
Sl/Sld mice have a defective hemopoietic microenvironment. It has been assumed, based upon previous studies, that the primary abnormality in these mice is simply lack of a necessary supportive or inductive material within the hemopoietic stroma. We used in vitro long-term bone marrow cultures to characterize further the nature of the hemopoietic microenvironmental defect in Sl/Sld mice. Sl/Sld mouse bone marrow cells consistently produced less than 10% of the total hemopoietic cells and multipotent and unipotent hemopoietic progenitor cells produced in cultures of marrow from normal, congenic +/+ mice. If fresh Sl/Sld and +/+ marrow cells were mixed prior to establishing long-term marrow cultures, there was a direct correlation between number of Sl/Sld cells added and degree of inhibition of +/+ hemopoiesis. A pre-established, confluent Sl/Sld adherent stromal layer inhibited hemopoiesis by fresh +/+ marrow cells by nearly 70%, as compared with dishes with irradiated +/+ or no stroma. This inhibitory effect was abrogated by irradiation of the Sl/Sld stroma prior to addition of the fresh +/+ marrow cells. Similarly, unirradiated, but not 9 to 200 Gy irradiated Sl/Sld stroma inhibited proliferation of the factor-dependent FDC-P1 hemopoietic progenitor cell line. Thus, the Sl/Sld hemopoietic microenvironment actively inhibits hemopoiesis in vitro, and this inhibition can be at least partially eliminated by irradiation of the Sl/Sld stroma.
Anemia, Macrocytic↗
A monokine stimulates production of human erythroid burst-promoting activity by endothelial cells in vitro.
Conditioned media were prepared from human peripheral blood monocytes and human umbilical vein endothelial cells. These media were assayed for erythroid burst-promoting activity (BPA) using human peripheral blood monocyte-depleted mononuclear cells as targets and assessing the stimulatory effect of the conditioned media on growth of early erythroid progenitor cells. Both monocytes and endothelial cells produced modest amounts of detectable BPA. Addition of varying concentrations of media conditioned by monocytes to plateau concentrations (5-10%) of media conditioned by endothelial cells had no additive effect. Endothelial cells incubated in the presence of 50% monocyte-conditioned medium produced 2.5- to 6.6-fold more BPA than did endothelial cells incubated only in control tissue culture medium. In contrast, endothelial cell conditioned medium did not stimulate increased BPA production by monocytes. Neither neutrophil- nor marrow fibroblastoid cell-conditioned medium stimulated BPA production by endothelial cells. Therefore, both monocytes and endothelial cells produce BPA. Moreover, monocytes produce a monokine that, in turn, stimulates the production of BPA by endothelial cells. Inasmuch as a monokine also has been shown to stimulate production of granulocyte-macrophage colony-stimulating activity, we propose that monocytes play a critical role in regulating the production of humoral regulators of the very early stages of hemopoietic cell differentiation.
Culture Media↗