Effect of IL-1, IL-6, GM-CSF and Erythropoietin on the in vitro Toxicity Associated with AZT on Human Bone Marrow Haematopoietic Progenitor Stem Cells: CFU-GM and BFU-E

The drug azidothymidine (AZT), a synthetic thymidine analogue, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of AZT has induced haematopoietic toxicity manifested by anaemia, neutropenia, and overall bone marrow suppression. Cytokines/growth factors, such as erythropoietin (EPO), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 (IL-1), interleukin-6 (IL-6), are agents responsible for the growth and regulation of normal haematopoiesis by influencing various classes of haematopoietic progenitors. We report the results of studies designed to investigate the capacity of these factors to influence the toxicity of AZT. Low density, ≤ 1.077 g/cm3, adherent and/or T-cell depleted normal human marrow cells were co-cultured in the presence or absence of AZT and the appropriate growth factor, i.e. EPO for the early erythroid haematopoietic colony-forming progenitor stem cell (BFU-E) and GM-CSF for the granulocyte–macrophage haematopoietic colony-forming progenitor stem cell (CFU-GM), in dose escalation studies. Additional experiments measured the effect of increasing doses of the cytokines IL-1 and IL-6, alone or in combination in the presence of increasing doses of either EPO or GM-CSF. When comparing the rate of AZT-induced inhibition of BFU-E in vitro, EPO alone (from 2 to 10 U/ml) did not reduce the magnitude of AZT toxicity on BFU-E. GM-CSF alone (up to 1000 U/ml) was ineffective in reversing AZT toxicity on CFU-GM; however, in the presence of either IL-1 and IL-6, AZT toxicity was decreased. These results indicate that certain cytokines/growth factors such as IL-1 or IL-6 in combination with EPO or GM-CSF, but not EPO or GM-CSF alone, may be effective in ameliorating AZT bone marrow toxicity; therefore the use of specific cytokines may be warranted as adjuvant therapy in AIDS.

Cytokine induction of a human acute myelogenous leukemia cell line (KG-1) to a CD1a + dendritic cell phenotype

Dendritic cells (DC) are highly specialized antigen-presenting cells located in many nonlymphoid tissues, and Langerhans cells (LC), a specialized form of DC, are found in the skin. LC as antigen-presenting cells play a critical role in the induction of allergic contact dermatitis. LC research is difficult because few LCs can be isolated from human skin, so efforts have focused on obtaining DCs from alternative sources. Mononuclear cells from peripheral blood and CD34+ stem cells from human cord blood and marrow can be induced to form phenotypic and functional DCs, but experiments of this type are expensive and the DC yield is low. We report here the induction of the myeloid leukemia cell line (KG-1) to a DC morphology and phenotype by culturing the cells in a defined cytokine cocktail. Morphologically, the KG-1-derived DCs are large irregularly shaped cells with prominent dendritic processes and hair-like cytoplasmic projections. Phenotypically, the KG-1-derived DCs lack lineage-specific markers, and express MHC class II, costimulatory molecules CD80 and CD86, and CD83. Functionally, KG-1-derived DCs are capable of phagocytosing latex microspheres and are able to induce a potent allogeneic T-cell response. Within the KG-1-derived DCs, a subpopulation maintains the DC phenotype and morphology described above but further develops CD1a+ marker expression similar to that of resident skin-derived LCs. These findings illustrate that phenotypic, morphologic and functional DCs can be derived from the KG-1 cell line.

Approaches for the development of cell-based in vitro methods for contact sensitization

Allergic contact dermatitis (ACD) is a cell-mediated immune response to small molecular weight chemicals that contact and penetrate the skin. There are a variety of characteristics that determine whether a chemical can function as a contact sensitizer (or allergen) including the ability to penetrate into the skin, react with protein and be recognized as antigenic by immune cells. The ultimate challenge for developing non-animal test methods for skin sensitization testing will be applying our mechanistic understanding of ACD to the design of predictive in vitro alternative test methods. Specifically, the in vitro approach should be designed so that a chemical's potential to penetrate the skin, react with protein/peptide (biotransformation may be required) and initiate an antigen-specific immune response is incorporated in the test methods developed. In this review, we have focused on cellular-based assays that have been developed or proposed for assessing a chemical's skin sensitization potential in vitro. All of the promising leads to date are based on observations made from in vivo studies conducted in animals and humans, and therefore have a strong mechanistic foundation. However, it remains to be demonstrated whether a single in vitro test, or several in vitro tests in combination, which model the critical steps in sensitization, can replace animal experiments for predicting contact allergic reactions in humans. Regardless, the future looks promising with continued development of our understanding of the chemical and biological aspects of allergic contact dermatitis, and most importantly, with the application of genomics/proteomics to this field on the immediate horizon.

Clonogenic potential of myeloid leukaemia cells in vitro is restricted to leukaemia cells expressing the CD34 antigen

Cells from patients with acute myeloid leukaemia (AML) or chronic myeloid leukaemia (CML) were separated into CD34-enriched and CD34-depleted subpopulations. The clonogenic capacities of these two subpopulations were then compared to each other and to the original unseparated cell population. In every study, the CD34-enriched subpopulation demonstrated a substantial increase in clonogenicity in vitro in comparison with the original cell population, while the reverse was the case for the CD34-depleted subpopulations. For reasons not clear at present, the enrichment for clonogenic cells far exceeded the enrichment for cells expressing the CD34 antigen. Additionally, the clonogenic potential was found to be unrelated to the level of myc expression in the various cell populations.

In vitro modulation of the toxicity associated with the use of zidovudine on normal murine, human, and murine retrovirus-infected hematopoietic progenitor stem cells with basic fibroblast growth factor and synergistic activity with interleukin-1

The antiviral drug used in the treatment of acquired immunodeficiency syndrome, zidovudine, has proved effective in ameliorating the morbidity and mortality associated with human immunodeficiency virus infection. However, associated with zidovudine is the development of severe bone marrow toxicity manifested by anemia, neutropenia, and occasionally thrombocytopenia. We report the results of studies that demonstrate the ability of basic fibroblast growth factor (B-FGF) to reduce zidovudine toxicity to several classes of hematopoietic progenitors (granulocyte-macrophage, CFU-GM; megakaryocyte. CFU-Meg; and erythroid, BFU-E) from normal murine, human, and murine retrovirus-infected bone marrow cells when cocultured with zidovudine in vitro. Optimal response to B-FGF was observed at a dose concentration of 10 ng/ml. The specificity of B-FGF was demonstrated in the presence of protamine sulfate, an effective inhibitor of B-FGF mitogenic activity. In addition, synergistic activity of B-FGF on zidovudine-induced hematopoietic stem cell toxicity was observed in the presence of interleukin 1 (IL-1) (30 ng/ml). These studies demonstrate that B-FGF is capable of reducing the hematopoietic toxicity associated with zidovudine and that such an effect can be amplified in the presence of IL-1.

Protooncogene expression in subpopulations of cells from leukemia patients

This report describes a method for preserving the light scatter patterns of cells in which myc and myb expression are being measured. Exposure of cells to 1% paraformaldehyde for 72 h prior to antibody staining for myc and myb proteins preserved the light scatter patterns. Using this method, myc and myb expression was found to be highest in lymphocytes and monocytes and lowest in granulocytes. The measurement of differences in the level of expression of these genes in subpopulations of leukemia cells obtained from individual patients is possible as is assessment of the levels of expression amongst normal and leukemia cells present in the same patient.

Effect of interleukin-1, GM-CSF, erythropoietin, and lithium on the toxicity associated with 3'-azido-3'-deoxythymidine (AZT) in vitro on hematopoietic progenitors (CFU-GM, CFU-MEG, and BFU-E) using murine retrovirus-infected hematopoietic cells

The drug 3'-azido-3'-deoxythymidine (AZT), a synthetic thymidine analogue, has been used clinically in the management of acquired immune deficiency syndrome (AIDS). The drug is an effective antiviral agent due to its ability to block reverse transcriptase activity. This action of AZT was demonstrated in the Rauscher leukemia virus (RLV)-induced murine erythroleukemia model system. Unfortunately, associated with AZT has been the development of hematopoietic toxicity manifested by anemia, neutropenia, and overall bone marrow suppression. Hematopoietic growth factors (GM-CSF, erythropoietin), cytokines (interleukin-1), and agents known to potentiate hematopoiesis (lithium) have been demonstrated to modulate drug and/or radiation-induced hematopoietic toxicity. We report the results of further studies designed to investigate the ability of GM-CSF, erythropoietin, interleukin-1, and lithium to modulate AZT toxicity on murine hematopoietic granulocyte-macrophage (CFU-GM), megakaryocytic (CFU-Meg), and erythroid (BFU-E) progenitors cultured from bone marrow and spleen cells from mice infected with RLV. Hematopoietic progenitors from either normal or RLV-infected animals when exposed to AZT demonstrated concentration-dependent toxicity and differed for each progenitor with BFU-E being the most sensitive (ID50 concentration, 5 x 10(-9) M) and CFU-GM the least sensitive (ID50 concentration, 5 x 10(-5) M). As has been previously demonstrated using normal murine hematopoietic progenitors, when cultured with RLV-infected marrow or spleen cells, addition of GM-CSF, Meg-CSF or erythropoietin failed to inhibit AZT toxicity in vitro on CFU-GM, CFU-Meg, and BFU-E, respectively. However, in the presence of interleukin-1 (recombinant human IL-1 alpha, 30 ngm) or lithium chloride (ultra-pure, 1.0 mM), AZT toxicity CFU-GM, CFU-Meg, and BFU-E cultured from RLV-infected marrow or spleen cells was reduced. These results further demonstrate interleukin-1 and lithium are effective in modulating the toxic action of AZT on hematopoietic progenitors and that RLV-infected animals serve as a useful viral model system to study the effect of agents capable of modulating hematopoiesis in the presence of the anti-viral drug AZT.

Isolation and characterization of the CD34+ hematopoietic progenitor cells from the peripheral blood of patients with chronic myeloid leukemia

A modified version of the original reported panning technique was used to separate CD34+ cells from the peripheral blood of patients with chronic myeloid leukemia (CML). In 13 out of 23 separations, populations of cells were obtained in which CD34+ cells constituted greater than 50% of the cells present. The best recovery and enrichment of the CD34+ cells was achieved when cells were obtained from patients in the accelerated phase of CML, when the cells were processed on the same day they were obtained from patients, and when adherence to soybean agglutinin flasks was used as a pre-enrichment step. In suspension culture, the CD34+ cells were capable of extensive proliferation and differentiation. In semi-solid culture, the number of colony-forming units (CFUs) directly correlated with CD34 positivity. The number of clonogenic cells/CD34+ cells was highest at the time of initial diagnosis of CML, fell during the chronic phase (CP) of the disease, and rose at the time of disease acceleration. This observation suggests that therapy during the CP of the disease produces a greater reduction in clonogenic cells than in the number of CD34+ cells. This effect disappears at the time of disease acceleration, presumably because of the development of drug resistance in the clonogenic cells.

Basic fibroblast growth factor (B-FGF) induces early- (CFU-s) and late-stage hematopoietic progenitor cell colony formation (CFU-gm, CFU-meg, and BFU-e) by synergizing with GM-CSF, Meg-CSF, and erythropoietin, and is a radioprotective agent in vitro

Basic fibroblastic growth factor (B-FGF) is a hormone-like protein which belongs to a class of heparin-binding growth factors. B-FGF is synthesized and released to circulate in the blood where it can be recognized by target cells through specific high-affinity plasma membrane receptors. B-FGF is known to be a potent mitogen for a number of specific cell types. We report data which demonstrates B-FGF can influence noncommited and specific lineage-derived hematopoietic progenitors when incubated in vitro. When combined with adherent cell-depleted normal murine marrow cells, B-FGF increased the number of both day 9 and day 12 spleen colony-forming units (CFU-s) from lethally irradiated animals. However, day 12-derived CFU-s were more sensitive to B-FGF, since optimal CFU-s production was observed at 10 ng/ml vs. 100 ng/ml for day 9 CFU-s (p less than 0.05). In adherent cell-depleted murine and human marrow cultures, the addition of B-FGF possessed synergistic activity in combination with the optimal concentration of GM-CSF for CFU-gm at a dose of 10 ng/ml which was inhibited in the presence of protamine sulfate (LD50 dose, 100 mu gm/ml), an inhibitor of B-FGF mitogenic activity, or in the presence of heparin (LD50 dose, 100 U/ml), an effective B-FGF binding agent. B-FGF also expressed synergistic activity in the presence of optimal concentrations of erythropoietin and Meg-CSF for murine and human BFU-e, and murine CFU-meg. No in vitro colony formation was observed when cells were cultured in the presence of B-FGF, but in the absence of the specific hematopoietic growth factor. Finally, B-FGF was also shown to be an effective radioprotective agent in vitro. Murine and human CFU-gm exposed to increasing doses of radiation (0.5 to 5 Gy) combined with GM-CSF and increasing doses of B-FGF (0.1 to 100 ng/ml) produced less radiation-induced toxicity compared to cultures containing GM-CSF alone. This data demonstrates B-FGF influences early- and late-stage hematopoietic progenitors, possesses synergistic activity with hematopoietic growth factors, and is a radioprotective agent in vitro. These results suggest B-FGF must be considered as a member of the family of molecules capable of influencing hematopoiesis in vitro.

Protection of 3'-azido-3'-deoxythymidine induced toxicity to murine hematopoietic progenitors (CFU-GM, BFU-E and CFU-MEG) with interleukin-1

3'-Azido-3'-deoxythymidine (AZT) has attained wide clinical utility in the treatment of acquired immunodeficiency syndrome (AIDS). Unfortunately, associated with AZT use, is the development of severe hematopoietic toxicity as manifested by anemia, neutropenia and overall bone marrow suppression. Interleukin-1 (IL-1), a cytokine, primarily produced by activated macrophages, has been involved in the control of hematopoiesis by acting synergistically with other hematopoietic growth factors, and has been demonstrated to be an effective agent in reducing the myelosuppression associated with the therapy for malignant disease. We report here the ability of recombinant human IL-1 alpha to protect normal murine hematopoietic progenitors (CFU-GM, BFU-E, and CFU-Meg) from the toxic effects of AZT. Following the determination of the LD50 dose for each progenitor, IL-1 was added in co-culture studies (10-1000 units; 0.001-1.0 micrograms/ml protein) with adherent cell depleted marrow. Marrow progenitors expressed differences in AZT sensitivity, e.g., BFU-E, LD50 5 x 10(-9)M; CFU-Meg, LD50 10(-7) M; CFU-GM, 5 x 10(-5) M respectively. IL-1 inhibited AZT induced toxicity. The maximum IL-1 dose effect was observed for CFU-GM and CFU-Meg at 300 units, 0.3 micrograms protein; however BFU-E required a dose of 600 units, 0.6 micrograms/ml protein to reverse the effects of AZT. These results demonstrate marrow progenitors respond differently to AZT and identifies the potential efficacy of IL-1 to minimize the hematopoietic toxicity associated with AZT treatment.

Effect of various interleukins (IL-1, IL-2, and IL-3) on the in vitro radioprotection of bone marrow progenitors (CFU-GM and CFU-MEG)

Radiation exposure to various systems can result in the development of severe toxicity, known as the acute radiation syndrome, with hematopoietic tissues being acutely susceptible to radiation-induced injury. Usually it is the degree of hematopoietic toxicity that determines the feasibility of further tumor control doses of therapy. Therefore the development of agents capable of protecting hematopoietic tissues could have important clinical applications. The cytokine interleukin-1 (IL-1) has been demonstrated to be an effective agent capable of protecting hematopoietic tissues in vivo from the toxicity associated with radiation exposure. We report here the results of studies designed to further investigate the capability of various cytokines (IL-1 and interleukins-2 and -3) to protect bone marrow-derived hematopoietic progenitors [granulocyte-macrophage and megakaryocyte colony-forming units (CFU-GM and CFU-Meg)] from radiation exposure in vitro. Only IL-1 was effective in protecting CFU-GM and CFU-Meg from radiation-induced toxicity in the range of 1-10 U/ml; however, no protection was observed when the radiation dose was greater than 300 rad. The ability of IL-1 to block radiation-induced toxicity was negated in the presence of an antibody to IL-1. These studies provide further information on the effectiveness of IL-1 in protecting in vitro hematopoietic tissues from toxicity associated with radiation exposure.

Modulation of murine hematopoiesis in vivo with recombinant murine interleukin-1

Interleukin-1 (IL-1), a cytokine, primarily produced by monocytes, is the molecule involved in mediating many of the body's responses associated with infection and inflammation. More recently, IL-1 has been shown to sustain elevated levels of circulating granulocytes, stimulate the production of granulocyte-macrophage colony stimulating factors (CSFs) in vitro, increase plasma levels of CSF, and act synergistically with CSFs to increase the number of granulocyte-macrophage progenitors (colony-forming units) (CFU-GM) in vitro. The purpose of this study was to investigate the effect of murine IL-1 on steady-state hematopoiesis in vivo. C3H/HeJ or its normal littermate C3H/HeN male mice were administered either murine recombinant IL-1 at 45, 50, 200, 225, or 900 units (0.0125-0.25 micrograms)/animal, or 200 units (0.05 micrograms) of semipurified IL-1 derived from P388D1 cell culture supernatants. Because one of the responses to IL-1 is increased prostaglandin (PG) production and with the known activity of PGs on hematopoiesis, additional studies incorporated the cyclooxygenase inhibitor indomethacin (IM) (10 mg/kg body weight). In order to study the effect of IL-1 in vivo on pluripotential progenitors (CFU-S), IL-1 was compared with recombinant murine GM-CSF (50, 200, and 900 units; 0.0125, 0.05, and 0.25 micrograms). Control groups consisted of animals receiving either lipopolysaccharide (0.5 mg/kg body weight) or phosphate-buffered saline where appropriate. After 24 h, animals were sacrificed, and their peripheral blood indices and stem cell content of both bone marrow and spleen were evaluated for various committed hematopoietic progenitors: CFU-GM, CFU-Meg, CFU-E, BFU-E, and CFU-DG. Circulating neutrophils were increased following IL-1; however, this increase was reduced following IM. IL-1 marrow-derived CFU-GM, CFU-E, BFU-E, and CFU-Meg were below controls. In contrast, splenic CFU-GM and CFU-Meg were significantly elevated with increasing IL-1 concentrations. Erythroid progenitors were increased following low IL-1 concentrations and reduced in animals receiving IM, thus indicating a role for prostaglandins in the mechanism of IL-1 for influencing hematopoiesis. CFU-DG were increased, however, only when animals were pretreated with IL-1 and their cells implanted into normal hosts, not when normal cells were implanted into animals pretreated with IL-1, indicating a potential target cell effect rather than an indirect, factor-related response.(ABSTRACT TRUNCATED AT 400 WORDS)

Toxicity of coumarin (1,2-benzopyrone) on human peripheral blood mononuclear cells and human and murine bone marrow progenitor stem cells

Coumarin (1,2-benzopyrone), in combination with cimetidine, has been subjected to separate clinical trials for the treatment of advanced renal cell carcinoma, malignant melanoma, and non-small cell lung cancer. While objective tumor regressions were observed only in renal carcinoma, no symptomatic or organ dysfunction toxicity was observed in any of the trials. The purpose of the present in vitro study was to determine the concentrations of coumarin and 7-hydroxycoumarin (7-HC) that would be toxic to human peripheral blood mononuclear cells (PB-MNC) and human and murine bone marrow (GM) progenitor stem cells. Coumarin was nontoxic for PB-MNC in concentrations up to 100 micrograms/ml. Concentrations of coumarin or 7-HC greater than or equal to 200 micrograms/ml produced significant suppression of human marrow GM stem cell activity. Coumarin greater than or equal to 25 micrograms/ml produced suppression of murine marrow GM stem cell activity. Differences in human and murine marrow sensitivity probably reflect interspecies differences in metabolism of coumarin. Correlations between toxic concentrations in vitro and maximally achievable serum concentration in vivo in humans await the results of further clinical trials.

In vitro effect of lithium on carbamazepine-induced inhibition of murine and human bone marrow-derived granulocyte-macrophage, erythroid, and megakaryocyte progenitor stem cells

Lithium (Li) is a known agent capable of producing leukocytosis, first observed in manic depressive patients receiving Li as therapy; however, a certain percentage of cases are nonresponsive to Li therapy. These patients are responsive to carbamazepine (CBZ); however, severe hematopoietic side effects have been associated with CBZ treatment such as leukopenia. We report here the results of dose-response studies (0.1-100 micrograms/ml) that demonstrate CBZ treatment inhibits both murine and human bone marrow-derived granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and megakaryocyte progenitor (CFU-Meg) cells. The addition of Li prior to and simultaneously with CBZ to marrow cultures was effective in reversing the CBZ-induced toxicity only in the presence of an optimal Li dose (1.0 mM) known to stimulate bone marrow function. However, when the addition of Li was delayed 24 hr to CBZ-treated cultures no protective effect was observed for any marrow progenitor. Thus, the time of Li-CBZ exposure is critical to observe the protective effect of Li. These results demonstrate that the leukopenia associated with CBZ treatment may be due to the ability of CBZ to inhibit marrow progenitor cells and suggest Li may be an effective agent to reverse the marrow toxic effects of CBZ.