Effect of recombinant human alpha interferon (INF) on chronic granulocytic leukaemia (CGL) clonogenic growth of bone marrow haematopoietic progenitors.

The effect of recombinant alpha interferon (INF) to the colony stimulating factor (CSF) production was examined with in vitro culture of the bone marrow of patients with chronic granulocytic leukaemia (CGL). It could be found that addition of interferon into a suspension of preincubated phytohaemagglutinin (PHA) lymphocytes from peripheral blood represents an inhibity factor for colony and cluster formation in autologic human marrow cultures.     

Treatment of severe aplastic anaemia with antilymphocyte globulin or bone-marrow transplantation.

Fifty-three patients with severe aplastic anaemia were admitted to this hospital between January 1976 and June 1980, of whom three arrived in terminal condition and died before treatment for their basic disease could be given. Thus 50 patients were treated and evaluated in a prospective study according to one protocol. Eighteen patients with an HLA-identical sibling underwent bone-marrow transplantation with the aim of achieving haematopoietic chimerism. Thirty-two patients without an HLA-identical sibling were given antilymphocyte globulin with or without an infusion of HLA-haplotype-identical marrow. All these 32 patients received low-dose androgens after the procedure. In the first group eight patients (44%) survived. In the two other groups, 22 patients survived (69%), of whom 20 were completely self-sustaining (63%). Engraftment and graft-versus-host disease did not occur in the group who received antilymphocyte globulin and haploidentical marrow, and the haematopoietic reconstitutions in these patients were all autologous. These results confirm the efficacy of antilymphocyte globulin in the treatment of severe aplastic anaemia and show that such treatment is at least as good as bone-marrow transplantation. Its mechanism of action remains unknown, but most patients with aplastic anaemia have a pool of haematopoietic stem cells able to repopulate the marrow after this type of treatment.     

Cytotoxic and stimulatory effects of antilymphocyte globulin (ALG) on hematopoiesis

Four different preparations of antilymphocyte/antithymocyte globulin were tested in vitro for their toxicity to lymphocytes and to hematopoietic precursor cells, depending on concentration and time. Complete lymphocytotoxicity was observed at concentrations from 6.3 to 25 micrograms/ml, and suppression of colony formation by hematopoietic precursors was seen at concentrations from 12.5 to 250 micrograms/ml. Prolonged incubation time did not increase lymphocytotoxicity but augmented precursor cell damage. Lymphocytotoxicity was comparable among the four preparations tested whereas precursor cell toxicity varied widely. Antilymphocyte globulin is mitogenic and stimulates the release of hematopoietic growth factor activity by peripheral blood cells. Absorption of ALG with human T-cells eliminated precursor cell toxicity and mitogenicity but not the capacity to release hematopoietic growth factors. These results show that dose/time schedules for ALG administration may be relevant and ALG acts by virtue of inhibitory and stimulatory antibody effects.     

The effect of antilymphocyte globulin (ALG) on human lymphocytes in vitro: inhibition of lymphotoxin production as a sensitive indicator for ALG activity.

The effect of antilymphocyte globulin (ALG) on lymphocyte function in the presence or absence of complement was investigated by comparing (i) ALG-induced blast-cell transformation, (ii) lymphotoxin production and (iii) its effect on PHA-induced blast-cell transformation, and on (iv) lymphotoxin production and (v) its cytolytic effect on lymphocytes. The most striking observation was that even extremely low doses of ALG were able to suppress significantly the lymphotoxin production without affecting other lymphocyte functions or cell viability; this effect was found to be independent of complement. From the comparisons of the mitogen-induced lymphocyte function in the presence of varying doses of ALG and PHA it can be concluded that ALG exerts its inhibitory effect on lymphokine production most likely by interfering with mitogen recognition rather than lymphokine secretion.     

The suppressive effect of antilymphocyte globulin (ALG) on the formation of anti-ALG antibodies]

The quantitative follow-up of precipitin formation against IgG aids in investigating the question whether ALG when applied to the organism tends to suppress the immune reaction against ALG. Rabbits locally immunized with pig anti-rabbit ALG were repeatedly treated i.v. with the same ALG, and to control groups normal pig IgG and NaCl saline was administered. It was found that antilymphocytic antibodies greatly suppressed the precipitation formation against IgG molecules. In the later stages of application this effect became more pronounced, evidently due to the specific suppression induced by long-term administration of relatively high doses of antigen. A possible improvement in the prevention of precipitin formation in ALG treated patients, i.e. substitution of currently applied tolerogenic dose of normal IgG by a similar dose of ALG is suggested.     

Differential effect of recombinant human leukocyte interferon on human leukemic and normal myeloid progenitor cells

Two separate clones of recombinant leukocyte interferon (IFLrA and IFLrD) inhibited the cloning efficiency in soft agar of the human leukemia cell lines HL-60 and KG-1. Inhibition of the growth in agar of normal human bone marrow myeloid progenitors was also observed, but this required considerably higher concentrations. IFLrA and IFLrD also inhibited the growth of HL-60 and KG-1 cells in suspension culture. This antiproliferative effect did not appear to be due to induction of maturation of these cells. Our results suggest that homogeneous preparations of interferon may be capable of exerting selective antiproliferative effects on malignant human myeloid progenitor cells in comparison to their normal counterparts.     

Effects of recombinant human stem cell factor (SCF) on the growth of human progenitor cells in vitro.

We have studied the effect of recombinant human Stem Cell Factor (SCF) on the growth of human peripheral blood, bone marrow, and cord blood progenitor cells in semisolid medium. While SCF alone had little colony-stimulating activity under fetal bovine serum (FBS)-deprived culture conditions, SCF synergized with erythropoietin (Epo), granulocyte/macrophage colony-stimulating factor (GM-CSF), and interleukin 3 (IL-3) to stimulate colony growth. Colony morphology was determined by the late-acting growth factor added along with SCF. Of all the combinations of growth factors, SCF plus IL-3 and Epo resulted in the largest number of mixed-cell colonies--a larger number than observed with IL-3 and Epo alone even in FBS-supplemented cultures. These results suggest that SCF is a growth factor that more specifically targets early progenitor cells (mixed-cell colony-forming cells) and has the capacity to synergize with a wide variety of other hematopoietic growth factors to cause the proliferation and differentiation of committed progenitor cells. Our studies indicate that SCF may be the earliest acting growth factor described to date.     

Effects of interferon alpha on human osteoprogenitor cell growth and differentiation in vitro.

The specific effects of interferon alpha (IFNalpha), on the differentiation pathways of human osteogenic cells are not known. The aim of this study was to investigate possible effects of IFNalpha on osteogenic development by investigating cell differentiation, colony formation (colony forming unit-fibroblastic, CFU-F), cell proliferation, and gene expression, in particular bone morphogenetic protein (BMP) expression, of human bone marrow osteoprogenitor cells. Human bone marrow fibroblasts were cultured with or without the addition of IFNalpha (5-1,000 IU/ml) in the presence and absence of dexamethasone (10 nM) and ascorbate (100 microM), which are agents known to affect osteogenic differentiation. IFNalpha produced a significant dose-dependent inhibition of cell proliferation and alkaline phosphatase specific activity at concentrations as low as 50 IU/ml. IFNalpha (50-1,000 IU/ml) inhibited the stimulation of alkaline phosphatase specific activity induced by ascorbate and dexamethasone. Examination of CFU-F showed dose- and time-dependent inhibitions of colony formation and reductions in both colony size and alkaline phosphatase-positive CFU-F colonies particularly at earlier times. Reactivity with an antibody specific for osteoprogenitors (HOP-26), was reduced in IFNalpha-treated cultures. Northern blot analysis showed a significant dose-dependent up-regulation of BMP-2 mRNA, estrogen receptor alpha mRNA and osteocalcin mRNA expression in ascorbate/dexamethasone cultures. In contrast, IFNalpha significantly inhibited BMP-2 mRNA expression in the absence of ascorbate and dexamethasone. In conclusion, IFNalpha inhibits human osteoprogenitor cell proliferation, CFU- F formation, HOP-26 expression, and alkaline phosphatase specific activity and modulates BMP-2 gene expression. These results suggest a role for IFNalpha in local bone turnover through the specific and direct modulation of osteoprogenitor proliferation and differentiation.     

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.     

Inhibition of fibroblast chemotaxis by recombinant human interferon gamma and interferon alpha

Interferons have recently been recognized as potent mediators in inflammatory processes, exerting profound effects on fibroblasts. The influence of interferons gamma and alpha on the chemotactic movement of fibroblasts toward various attractants was, therefore, investigated. Normal human adult and embryonal dermal fibroblasts, fibrosarcoma-derived fibroblasts and SV40-transformed fibroblasts were tested against conditioned medium from fibroblasts, the chemotactic peptide C-140 of fibronectin, platelet-derived growth factor, and leukotriene B4 as attractants in the presence or absence of the interferons. Interferons gamma and alpha inhibited chemotaxis in a dose-dependent manner and at concentrations at least as low as 10(-2) ng/ml. Inhibition was noticeable when the cells were exposed to interferon for as short a period as 60 minutes, and the effect was not readily reversible. Inhibition occurred when the cells came from sparse or dense cultures, but when platelet-derived growth factor was the attractant and the cells had been grown at low density there was no inhibition. It is concluded that this is a specific effect, not to be wholly explained by overall increase in membrane rigidity. Inhibition of fibroblast chemotaxis by interferons may be an important regulatory mechanism during wound healing or fibrosis and metastatic spread of tumor cells.     

High cell density fermentation of recombinant Escherichia coli expressing human interferon alpha 1

Summary A defined medium was developed which, by means of a specific fed-batch mode, allows growth of the recombinant Escherichia coli strain TG1 (pBB210) up to a cell density of 60 g dry weight/l. Apart from glucose and aqueous ammonia fed as carbon and nitrogen sources, it was unnecessary to supply other nutrients or O₂-enriched air. Aqueous ammonia also served for pH control. The pO₂ level was kept at 20% saturation via closed-loop controls operating the two output variables of stirrer speed and glucose feeding rate. This fed-batch method prevented significant accumulation of acetate and other metabolic by-products. The recombinant E. coli expressed interferon alpha 1 more efficiently at a lower specific growth rate (_Pr 0.15 h^–1) than at the maximum specific growth rate (_max = 0.45 h^–1). Therefore, fermentation in the batch phase at _max was only allowed to continue up to a medium cell density. In the succeeding fed-batch phase, the specific growth rate was reduced to _Pr by increasing the stirrer speed according to an empirically developed time scale. Offprint requests to: D. Riesenberg     

Effects of recombinant human interferon alpha on human megakaryocyte and fibroblast colony formation

Effects of recombinant human interferon alpha (HuIFN-alpha) on human megakaryocyte (CFU-MK) and fibroblast (CFU-F) colony-forming cell growth were studied. Concentration-dependent inhibition of both CFU-MK and CFU-F by HuIFN-alpha was demonstrated. Statistically significant suppression of both CFU-MK and CFU-F was seen at a HuIFN-alpha concentration of 1000 U/ml or greater. No significant difference was found between HuIFN-alpha treated cultures and controls for the distribution of CFU-MK types and for the size and cell morphology of CFU-F. When a concentration of 1000 u/ml HuIFN-alpha was added at varying time points during the marrow cultures, decreased numbers of megakaryocyte and fibroblast colonies only appeared at the early days of cultures. When bone marrow cells were incubated with HuIFN-alpha for different periods of time prior to initiation of cultures, a reduction of megakaryocyte colony formation also occurred. These studies demonstrate a suppressive effect of HuIFN-alpha on human CFU-MK and CFU-F growth. This effect seems to occur at the initial stages of CFU-MK and CFU-F development.     

Triple alpha-genes (alpha alpha alpha anti3.7) in a patient with sickle cell anaemia.

This paper reports the case of a 17-year-old male student from the Jaizan area in south-western Saudi Arabia who had sickle cell anaemia and possessed three alpha-genes on one chromosome (alpha alpha alpha anti3.7) and two on the other. The clinical manifestations were severe, with frequent blood transfusion requirements and frequent episodes of painful crises, severe anaemia and tissue involvement. In comparison with age and sex-matched sickle cell anaemia patients with one alpha-gene deletion (-alpha/alpha alpha), or a normal alpha-gene arrangement (alpha alpha/alpha alpha), a more severe disease presentation was obvious in the propositus. It is suggested that with the surplus alpha-globin chains, more severe haematological and clinical abnormalities occur, these influence the phenotypic expression of sickle cell anaemia. However, more patients with this type of gene arrangement must be studied before a definite conclusion can be reached regarding the influence of excess alpha-globin chains on the presentation of sickle cell anaemia.     

Human interferon and cell growth inhibition. V. Effect of ouabain on interferon activities

The effect of ouabain on the antiviral and anticellular activities of interferon and its components was tested in RSb cells. These cells were found to be inhibited in growth by both components. Ouabain, known to block the antiviral effect of interferon without affecting the growth inhibitory effect, depressed both effects of the antiviral component. The effect of the growth inhibitory component was unaltered by the drug. The results support earlier suggestions that two different mechanisms may be involved in the growth regulation by interferon.     

Effect of human recombinant interferon on cytotoxic activity of natural killer (NK) cells and monocytes

Studies have been performed on the in vitro immunologic effects of homogeneous recombinant human leukocyte interferon, IFLrA. Large granular lymphocytes, enriched for natural killer (NK) cell activity, were pretreated wtih IFLrA or natural interferon preparations and then tested for augmentation of NK activity and of antibody-dependent cell-mediated cytoxicity (ADCC). Monocytes were tested for cytolytic and cytostatic activity in 48–72 hr radioisotopic assays performed in the presence or absence of interferon. Treatment with IFLrA caused significant augmentation of NK, ADCC, and monocyte-mediated cytotoxic activities. Even 10 units of IFLrA induced augmentation of NK activity, and 100 units or more boosted monocyte-mediated activity. The effects in each of these assays were species-specific, with no detectable effects on the activity of mouse effector cells. These results indicate that homogeneous recombinant interferon has potent in vitro immunomodulating effects and thus provide a basis for carefully examining the in vivo effects of this protein on host defenses in forthcoming clinical trials with cancer patients.