In vivo studies on hemopoietic stem cells and target cells for Friend virus infection in vitro

Friend virus replicating target cells have been characterized by in vitro infection of bone marrow cells from DBA/2 mice after multiple injections of hydroxyurea (HU), after bleeding and/or hypertransfusion and after busulfan treatment. The concentration of CFUS, BFUE and CFUE in the cell suspension was correlated with the number of infectious centers (IC) induced after infection. HU treated mice were also infected in vivo. The results demonstrate that there is almost no target cell 4 h after the last of 4 HU injections. The number of IC induced could correlate with the numbers of CFUS in the HU experiment, but this possibility can be rejected based on the busulfan experiments. All results, including those after bleeding and/or hypertransfusion are compatible with a target cell between BFUE and CFUE, as suggested by other in vitro infection methods and also in vivo experiments.

Animal model of human disease: myelogenous leukemia in the RF mouse

Images

A monoclonal antibody that detects expression of transferrin receptor in human erythroid precursor cells

A monoclonal antibody, L5.1, obtained by immunizing a Balb/c mouse with HL60 human promyelocytic leukemia cells, was found to react with both HL60 cells and with the K562(S) cell line. This monoclonal antibody binds and immunoprecipitates a glycoprotein (Mr 87,000) present on the cell surface membrane of K562(S) as a disulfide bonded dimer. In competition experiments L5.1 competes with both transferrin and OKT9 (a known antitransferrin receptor antibody) for binding to target K562(S) erythroleukemia cells. Binding of both L5.1 and transferrin to the surface of K562(S) cells is inhibited by treatment with 12--O-tetradecanoyl-phorbol-13-acetate, and the extent and time course of inhibition is similar in both cases. Cell sorting analysis of normal human marrow cells incubated with L5.1 indicates that L5.1 reacts strongly with all the morphologically recognizable erythroid lineage precursors, from the pronormoblast to the orthochromatic normoblast, and with reticulocytes. Erythrocytes, myeloid elements, monocytes, megakaryocytes and platelets, peripheral blood B and T lymphocytes do not bind significantly with this antibody and only a small fraction of promyelocytes was reactive. Antibody L5.1 did not react with leukemic cells of patients with acute lymphoblastic, myeloblastic and promyelocytic leukemias, but it did react with some established B (1 of 5) and T (2 of 3) cell lines, and a myeloid (1 of 3) cell line, and with PHA-stimulated peripheral blood lymphocytes. The nonhemopoietic cell lines tested did not bind with L5.1 with the exception of a colorectal adenocarcinoma and a melanoma cell line, which were both strongly positive. The relationship of antibody L5.1 to other monoclonal antibodies that bind the transferrin receptor is discussed.

[Molecular heterogeneity and complex-forming capacity of plasma ribonucleases in leukemia]

Molecular polymorphism and complex-formation ability of ribonucleases, obtained from blood plasma of healthy persons and of patients with acute leukemia as well as from blood plasma of rats with experimental Svec leukemia, were studied using isoelectric focusing, ion exchange chromatography, gel and membrane filtration techniques. Molecular forms of the enzyme were not altered in leukemic patients and animals as compared with normal state but the ability of the enzyme to form complexes with other blood plasma components was markedly decreased in the pathology. Increase in content of polyamines, found in blood of leukemic patients and animals, might be among the reasons responsible for decrease of the enzyme ability to bind with blood plasma proteins.

Identification and quantitation of embryonic and three types of fetal hemoglobin produced on induction of the human pluripotent leukemia cell line K-562 with hemin

The hemoglobins synthesized by the pluripotent K-562 leukemia cell line of human origin after induction with hemin have been isolated by DEAE-cellulose chromatography and characterized by electrophoresis, high pressure liquid chromatography, and a radioimmunological assay. Six hemoglobin zones have been observed with the following likely compositions. Zone 1: alpha 2 epsilon 2, or HB Gower-2; zone 2: zeta 2 epsilon 2, or HB Gower-1; zone 3: zeta 2 gamma 2, or HB Portland-I; zone 4: Hb F, or alpha 2 gamma 2; zone 5: a mixture of acetylated HB Portland-I and Hb F; zone 6: Hb Bart's, or gamma 4. The embryonic Hbs (zones 1, 2, and 3) constituted 50%-75% of the total Hb present; the quantities varied from one experiment to the other. Both Hb Gower-1 and Hb Gower-2 were present. The gamma chain was heterogeneous and contained the G gamma, A gamma I, and A gamma T types in a ratio of about 4:2:1, indicating a heterozygosity for the Ile leads to Thr substitution at position gamma 75. The methodology used can be applied for additional studies evaluating quantitative changes in Hb types due to in vitro manipulations.

Hematopoietic stem cells in Friend murine leukemia virus infected mice undergoing chemotherapy: failure to eradicate Ep-independent erythropoiesis by BCNU

DBA/2 mice, 12 days after infection with the polycythemia-inducing Friend virus (F-MulV-P), were treated with a single dose of BCNU. The effect of 35 mg/kg and lower doses on the different stem cell pools (CFUS, CFUC, CFUE) and the F-MulV-P specific ICPC (infectious centers producing cells) and Ep-independent CFUE was studied in detail. The depression of CFUS and CFUC was comparable in normal and F-MuLV-P infected mice. The CFUE population of virus infected mice, which had been completely Ep independent before treatment, showed only some normal Ep dependent colony growth thereafter. This finding was in contrast to the effect of multiple doses of Hydroxyurea, studied previously, which had given the same quantitative depression of CFUS and CFUC. Possible reasons for this failure are discussed; they may be the more proliferation independent mode of action of BCNU and the delayed hemopoietic regeneration.

Sources and biology of regulatory factors active on mouse myeloid leukemic cells

The action of serum or cells in enforcing differentiation in mouse myelomonocytic leukemic cells was monitored in agar cultures of WEHI-3B leukemic cells. The repeated intravenous injection of 5 micrograms endotoxin initially increased serum differentiating activity but after the third injection responses to further injections decreased markedly. Congenitally athymic (nude) mice exhibited normal rises in serum differentiating activity when injected with endotoxin but C3H HeJ mice failed to respond to challenge with purified lipid A. Whole body irradiation up to 1,200 rads did not increase serum differentiating activity but did not suppress responses to challenge injection of endotoxin. Coculture of WEHI-3B cells with peritoneal cells from normal or irradiated BALB/c mice caused marked granulocytic differentiation in WEHI-3B colonies. This effect was not seen if leukemic cells were cultured with thymus, spleen, or bone marrow cells. The serum halflife of the factor in postendotoxin serum enforcing differentiation of WEHI-3B cells was shown to be 1.5-2.3 hr.

Blast crisis associated with granulocytic leukemia in strain 13 guinea pigs

A transplantable granulocytic leukemia (GL-13) in inbred strain 13 guinea pigs had been shown previously to have many characteristics in common with human CML except that a blast crisis did not occur in the terminal stage of the disease. We report here that, after the 25th transplant generation, leukemic guinea pigs began to develop a blast crisis similar to that seen in human CML. This feature of the disease is still present after 90 transplant generations. The transplantation conditions necessary to produce the leukemia (now referred to as GL-13-BC) with a predictable clinical and hematological course over a short interval are described. Thus, s.c. injection of 3.0 X 10(6) leukemic cells results in a slowly rising leukocyte count, due mainly to increasing numbers of myelocytes and mature granulocytes, at about 3 weeks after injection. At this early stage the spleen weights of the leukemic animals are about seven times greater than those of normal controls. Approximately 4-7 days later the leukocyte count rises sharply due to a blast crisis and the animals die shortly thereafter with a mean survival time of 30 (range 25-32) days. It is proposed that the GL-13-BC leukemia could serve as a useful model for investigating the problem of blast crisis associated with human CML.

The role of erythropoietin in erythroid colony formation from Rauscher leukemia virus-infected mice

Recent work has led to conflicting results regarding the in vitro control of erythropoiesis in mice infected with Rauscher Leukemia Virus (RLV). Some reports claimed that marrow or splenic erythropoiesis from RLV-infected mice were independent of exogenously added erythropoietin (Ep), while other reports supported the view that erythroid stem cells (CFUE) from RLV-infected mice required EP for erythroid differentiation and proliferation. Results reported here demonstrate that erythroid differentiation and proliferation. Results reported here demonstrate that CFUE cultured from RLV-inoculated mice are dependent upon Ep for erythroid differentiation. Furthermore, RLV-infected mice which had received transfusions to suppress the endogenous production of Ep not only had a reduction in spleen weight and reticulocyte percentage, but also reduced numbers of CFUE and BFUE.

Leukocyte mobilization in mice by polyanions. Decline of leukocyte mobilizing capacity after transplantation of lymphoma

The leukocyte mobilizing polyanions dextran sulphate (DS) and polymethacrylic acid (PMAA) were administered to AKR and (C57BL x CBA) F1 mice at various times after transplantation of syngeneic lymphoma cells. In nonleukaemic mice DS and PMAA increased the number of circulating leukocytes 3--4-fold. The extent of leukocyte mobilization in leukaemic mice depended on the interval between transplantation of the lymphoma cells and injection of the polyanion. During the development of leukaemia in AKR as well as in (C57BL x CBA) F1 mice the capacity to react upon injection of polyanions with leukocyte mobilization gradually decreased. For DS, this decrease started before the number of leukocytes increased in the peripheral blood. On the other hand, the capacity for PMAA-induced leukocyte mobilization was fully preserved for several more days. In heavily leukaemic mice neither DS nor PMAA could further increase the number of peripheral blood leukocytes. In such mice the distribution pattern of leukaemic blast cells, small lymphocytes, granulocytes and monocytes was also hardly or not affected by injection of the polyanion.

Reproducibility of serum haptoglobin profiles in mice with transplanted tumors

To determine whether the elevation of serum haptoglobin (Hp) elicited by many tumors is associated with properties of the tumor, Hp levels were determined during successive passages of two transplantable fibrosarcomas and two leukemia lines in syngeneic mice. Characteristic and unique profiles were elicited by each of the four tumors and were reproducible in each of three successive transplant generations. The Hp profiles elicited by EL4 leukemia cells were similar in allogeneic and syngeneic mice, except that the Hp maxima were greater in the allogeneic mice. Preimmunization with EL4 cells or pretreatment with immune serum or spleen cells obliterated the Hp response normally elicited by EL4 cells in allogeneic mice. These results suggest that the Hp response elicited by a tumor is associated with transmissible characteristics of the tumor.

Differences in the plasma kinetics of daunorubicin in normal and leukemic rats

The plasma pharmacokinetics of the anthracycline drug daunorubicin in doses of 1 and 10 mg/kg body weight were compared in normal and leukemic inbred Sutton-August rats (50-70 x 10(9) leukemic cells/1 blood). The area under the plasma concentration versus time curve was about 25 times larger in the leukemic rats at both dose levels. The data indicate that daunorubicin has a lower volume of distribution in leukemic rats as compared with normals. The large reduction in plasma clearance of daunorubicin in the leukemic rats can to some extent be explained by impairment of hepatic and renal functions but the results indicate that the leukemic state per se was of importance for the observed pharmacokinetic differences. This finding may be of importance for the treatment of patients with a high leukemic cell load, since higher retention of the drug in the central compartment leads to lower concentrations in poorly vascularized tissues, which favours the development of resistant leukemic cell clones.

Erythrocyte production and survival in Rauscher murine leukemia virus-infected BABL/c mice

Red blood cell production in normal and Rauscher murine leukemia virus-infected mice was investigated using 55Fe as a marker. Using autoradiographic techniques, increases in the percentage of labeling of red blood cells were found in blood smears taken at different time intervals after pulse labeling of the erythroid precursor cells. The total reticulocyte production per unit time is more than 2.8-fold in Rauscher murine leukemia virus-infected mice as compared with that in uninfected mice. The life span of the newly formed cells was measured after [51Cr]chromate labeling of transfused erythrocytes in infected and in control mice. The life span was indicated by time that one-half of the labeled erythrocytes disappeared (t1/2) was reduced to one-quarter of that of erythrocytes of uninfected mice. The functioning of the newly formed cells was analyzed by measuring the glucose utilization versus lactate production and by measuring the activities of a number of enzymes involved in glucose metabolism. Comparison of glucose metabolism in normal and leukemic mice and in mice recovering from artificially induced anemia revealed that the metabolic activity of erythrocytes from leukemic mice corresponds to the activity of young erythrocyte populations. The increased reticulocyte production is, apparently, a result of the degree of anemia in infected animals. This anemia is not compensated for, however, since the loss of erythrocytes surpasses the flux of new red blood cells from the hematopoietic organs into the peripheral blood.

Methylcellulose cultures clotted and stained for permanent record

Whereas methylcellulose cultures have been valuable for biochemical studies on hemopoiesis in vitro, it has been difficult to study cellular morphology in these cultures. We have found that clotting factors can be added at any time during the culture period and non-adherent cells become entrapped in a semisolid clot. The clot can be removed, fixed and stained for detailed microscopic examination.

Insulin binding and response in erythroblastic leukemic cells

Mammalian erythrocytes have been shown to bind, but not to respond to, physiologic doses of insulin. Insulin binding was studied in normal rat erythrocytes and erythroblastic leukemic (EBL) cells by standard 125I-insulin competitive binding assays. EBL cells exhibited marked insulin degradation, which was time, temperature, and concentration dependent and was mediated by both cell-bound and soluble enzymes. Bacitracin or bovine serum albumin was used to inhibit such degradation in a dose-dependent fashion to allow meaningful data analysis. Insulin binding studies showed a greater than 10-fold increase of specific binding to EBL cells compared with erythrocytes. Scatchard analysis was consistent with increases predominantly in the number of receptors on EBL cells. Concordant with increased insulin binding, EBL cells demonstrated increased transport of alpha-aminolsobutyric acid and increased incorporation of uridine into ribonucleic acid in response to physiologic doses of insulin (100 microunits/ml). It can be concluded that EBL cells may serve as useful models of erythroblasts to explore the relationships between insulin binding, response, and cell maturation.

Glucocorticoid receptors in peripheral blood lymphocytes from bovine leukemia virus-infected cows with persistent lymphocytosis

Bovine leukemia virus-infected cows with persistent lymphocytosis have an expanded population of B-lymphocytes in the peripheral blood that is sensitive to glucocorticoids in vitro and in vivo. We examined peripheral blood lymphocytes from cows with persistent lymphocytosis for the presence of specific glucocorticoid receptors. Steroid binding in intact cells was determined by a whole cell competitive binding assay using [3H]dexamethasone. The binding of the glucocorticoid to receptor was characterized in terms of affinity, specificity, and kinetics of the reaction. We found that peripheral blood lymphocytes from three cows with persistent lymphocytosis had 5000 to 6600 specific glucocorticoid-binding sites/cell. Compared with that reported for human lymphoid cells, glucocorticoid receptors in the bovine lymphocytes were found to have a greater affinity for the steroid with an association rate that was three times faster and a dissociation rate that was less than one-half of the former. We examined the biological half-life of hydrocortisone in the normal cow and found it to be 69.3 min, which is shorter than that reported for other domestic species and humans. The kinetics and affinity of the steroid binding may explain why in vivo glucocorticoid sensitivity was demonstrated in these animals despite the fact that elevated levels of plasma corticoids were not maintained. These results suggest that glucocorticoid sensitivity may be influenced by the nature of the binding reaction between steroid and receptor.

Separation of different molecular forms of macrophage- and granulocyte-inducing proteins for normal and leukemic myeloid cells

It is shown that serum of mice treated with endotoxin (ES) contains three separable and functionally distinct forms of macrophage- and granulocyte-inducing (MGI) proteins. One form (MGI-1M) induced the formation of macrophage colonies from normal bone-marrow cells and showed on gel filtration an apparent molecular weight of 300,000; a second form (MGI-1G) induced the formation of granulocyte colonies from normal bone-marrow cells and had an apparent molecular weight of 45-100,000; and the third form (MGI-2) induced the normal differentiation of MGI+D+ myeloid leukemic cells to macrophages and granulocytes and had an apparent molecular weight of 28,000. Studies on the time course of the decrease of these three activities in ES have indicated that MGI-2 was more readily inactivated in vivo than MGI-1M and MGI-1G. The MGI-1M in ES isolated after gel filtration was completely neutralized by an antiserum to MGI-1 from mouse L-cells, whereas the isolated MGI-1G and MGI-2 were not affected by this antiserum. Gel filtration under dissociating conditions (6 M guanidinium chloride) resulted in a reduction of the apparent molecular weights of MGI-1M from 300,000 to 42,000, and of MGI-1G from 45-100,000 to 28,000, while it produced no change in the 28,000 apparent molecular weight of MGI-2. Similar studies with conditioned medium produced in vitro from mouse lung and peritoneal macrophages showed that in these conditioned media, MGI-1 (both G and M) in the native form had an apparent molecular weight of 41,000 and MGI-2 of 24,000, and that both MGI-1 and 2 had an apparent molecular weight of 24,000 under dissociating conditions. The results indicate that MGI-1 exists in serum in vivo and in these conditioned media as aggregated proteins, whereas MGI-2 does not, and that macrophages and lung tissue are not the only source of the MGI proteins found in ES. It is suggested that all three forms of MGI activity are derived from one precursor protein; that only the MGI-2 form assayed on leukemic cells should be used for treatment based on the induction of normal cell differentiation in myeloid leukemia; and that MGI-2 may serve as a survey mechanism for inducing differentiation in myeloid leukemic cells that have lost their responsiveness to the MGI-1 molecules that control the viability, proliferation and differentiation of normal myeloblasts.

Antiviral and interferon-inducing properties of interferon inducers administered with prostaglandins

Prostaglandins enhanced the interferon response and therapeutic activity of interferon inducers in Friend leukemia virus-infected mice. A similar enhancement in interfron responsiveness but not antiviral activity was observed in mice infected with rapidly acute viruses.

Colony stimulating activity in sera of erythroleukemic mice (RLV-A)

RLV-A serum activity was measured by the agar colony assay to determine the effect of this erythroid dyscrasia on the granulopoietic humoral regulator, colony stimulating factor (CSF). In general, the sera of early, midstage and terminal animals not given endotoxin had high cluster forming properties compared to normal sera. The sera of early, midstage, and terminal mice treated with endotoxin had only a fraction of the colony forming ability of serum obtained from normal endotoxin-treated mice (EMS) with the earliest stages of the disease showing least activity followed by a rise in activity paralleling normal EMS, as the disease progressed. Sera from RLV-A endotoxin treated mice retained ability to stimulate cluster growth especially when compared to the slight activity displayed by normal endotoxin treated mouse sera.

Effects of tilorone on hemopoietic stem cells and on the development of Friend leukemia

Hematological effects of tilorone, an interferon inducer, on the hematopoietic cell system of normal CBA/Ca mice and on the development of Friend virus (FV-P)-induced polycythemia in DBA/2 mice were studied. In normal mice 80 mg/kg IP had a marked depressive effect on pluripotent (CFU-s), granuloid committed (CFU-C), and erythroid committed (CFU-E) stem cells with regeneration between days 5 and 12. In bone marrow smears only lymphopenia was detected. Treatment of mice before FV-P infection caused a slight retardation in the development of the splenomegaly and the transformation of bone marrow cells to Ep independence. Repeated treatment after FV-P infection also reduced the increase in spleen weight and the development of reticulocytosis, but the Ep independence of bone marrow and spleen cells was not influenced. In vitro exposure of normal cells and cells from FV-P-infected animals to the drug showed the same sensitivity of colony growth in normal as well as in Ep-independent CFU-E. The action of the drug on Friend leukemia is at least in part considered a toxic effect on the hematopoietic stem cell system.

Binding of lectins to leukemic cell lines

The binding of 12 different fluorescein-conjugated lectins to 10 ALL (acute lymphoblastic leukemia) cell lines and two cell lines derived from patients in blast crisis of myeloid leukemia was examined. The specificity of the membrane fluorescence was demonstrated by inhibition with various saccharides. Three of the lectins bound to all cell lines, four bound to only some of the lines, and five were not bound. There was no correlation between the binding pattern and the immunological phenotype of the cultured lymphoblasts. The lectin from Lens culinaris, however, in the experimental condition used (incubation at 4 degrees C, fluorescein conjugation at pH 8.5), bound only to the cell membranes of 'Ia-like antigen, positive cell lines. Although three lectins (Lens culinaris, Pisum sativum, concanavalin A) had an identical monosaccharide specificity, they bound to different cell lines. Membrane fluorescence with the lectins from Helix pomatia, Arachis hypogea, and Ricinus communis (MW 60,000) was achieved after treatment with neuraminidase. It was shown that binding of the lectins from Helix pomatia and Ricinus communis 60 was effected by enzymatically exposed glycoproteins, whereas the lectin Arachis hypogea was bound via neuraminidase which stuck to the cell membrane.

AKR murine leukemia viruses and long-term bone marrow cultures from AKR and SJL mice

We have evaluated the effects of AKR mouse retroviruses on a system of long-term bone marrow cultures which allows prolonged replication of hemopoietic stem cells (CFUs) and granulocyte-monocyte progenitors with production of mature granulocytes. Ecotropic-nononcogenic virus is expressed in all cultures and does not adversely effect stem cell replication. We found, however, that cultures established from mice treated in vivo with lymphomagenic AKR viruses (Gross murine leukemia virus and AKR SL3 murine leukemia virus) showed a more rapid decline in CFUs and CFUc than cultures from "normal" AKR mice. Only the former cultures were found to produce lymphomagenic viruses. Furthermore, it was shown that addition of lymphomagenic virus to three-week marrow cultures established from AKR and SJL mice also caused a prompt decline in progenitor cell production and granulopoiesis when compared to medium-treated control cultures. The fate of all cultures was a loss of CFUc and granulocytes with a continuous production of macrophages. The change to macrophage production occurred earlier in the cultures treated with lymphomagenic virus or in those derived from lymphomagenic virus-treated animals. A study of these bone marrow-drived macrophage cultures, as well as cultures of similar morphology but of thymic origin, showed that they could be maintained as continuous lines. Cells from three of the cultures from lymphomagenic virus-treated animals plroduced locally growing sarcoma when inoculated into mice. The macrophages from the declined marrow cultures differed in certain properties from those of the established lines.