Detection of luxol-fast-blue positive cells in human promyelocytic leukemia cell line HL-60

Differentiation of HL-60 cells toward the eosinophilic series has not been reported previously. Eosinophil granule specific staining with Luxol-fast-blue was used to determine if HL-60 cells could differentiate into the eosinophilic lineage. The specificity of the Luxol-fast-blue stain for cells of the eosinophilic series was substantiated by comparison of the staining of cells from a patient with an eosinophilic syndrome by Wright-Giemsa and Luxol-fast-blue. Luxol-fast-blue positivity was most notable in cells found in colonies formed from HL-60 clonogenic cells in semisolid agar medium. Colony and cluster formation was spontaneous but in the presence of medium conditioned by either human placental cells or the human monocyte-like cell line, GCT, Luxol-fast-blue positive colonies and clusters were detected at a higher frequency.

Identification of leukemia-associated inhibitory activity as acidic isoferritins. A regulatory role for acidic isoferritins in the production of granulocytes and macrophages

Acidic isoferritins have been identified as leukemia-associated inhibitory activity (LIA), which suppresses colony and cluster formation of colony-forming unit-granulocyte macrophages from normal donors but not from patients with leukemia. LIA was detected in all ferritin preparations tested, including ferritin isolated from normal heart, spleen, liver, and placental tissues, and from the spleens of patients with chronic myelogenous leukemia and Hodgkin's disease. Purified preparations of LIA were composed almost entirely of acidic isoferritins, as determined by immunoassay, radioimmunoassay, and isoelectric focusing. The inhibitory activity in the LIA and ferritin samples was inactivated by a battery of antisera specific for ferritin, including those prepared against acidic isoferritins from normal heart and spleen tissues from patients with Hodgkin's disease, and those previously absorbed with basic isoferritins. Antisera absorbed with acidic isoferritins did not inactivate the inhibitory activity. Separation of LIA and chronic myelogenous leukemia and normal spleen ferritin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing confirmed that the regions of peak inhibitory activity corresponded in each to an apparent molecular weight of approximately 550,000 and to a pI value of 4.7. Similar physicochemical characteristics included inactivation by methods that dissociate ferritin molecules into subunits and by treatment with trypsin, chymotrypsin, pronase, and periodate. The purified preparations were extremely stable to heat treatment. The glycoprotein nature of the inhibitory activity was substantiated because it bound to concanavalin A-Sepharose and was eluted off by alpha-methyl mannose. Inhibitory activity of the activity of the acidic isoferritins was detected at concentrations as low as 10(-17)-10(-19) M and iron saturation did not appear to be necessary for its action. These results implicate acidic isoferritins in the regulation of normal myelopoiesis and suggest a role for them in the progression of leukemia.

Isolation and biochemical characterization of leukemia-associated inhibitory activity that suppresses colony and cluster formation of cells

Leukemia-associated inhibitory activity suppresses colony and cluster formation in vitro cells derived from granulocyte-macrophage progenitor cells of normal donors. It does not inhibit these same progenitor cells from patients with leukemia and it may contribute to the proliferative advantage leukemia cells appear to possess over normal hematopoietic cells during acute leukemia. The inhibitory activity was isolated by a combination of procedures including: ultracentrifugation, Sephadex G-200, carboxymethylcellulose, SDS-polyacrylamide gel electrophoresis, thin-layer and preparative isoelectric focusing and concanavalin A-Sepharose. Leukemia-associated inhibitory activity was characterized as a glycoprotein. it was inactivated by trypsin, chymotrypsin, pronase and periodate treatment. It bound to and was eluted by alpha-methylmannose from concanavalin A-Sepharose columns and had an apparent Mr range of 450-550 000 and an isoelectric focus value between pH 4.6 and 4.9. Crude leukemia associated inhibitory activity was temperature sensitive but the more purified preparations were heat stable.

Induction of leukemia-associated inhibitory activity and bone marrow granulocyte-macrophage progenitor cell alterations during infection with Abelson virus

Neonatal and adult BALB/c mice were investigated in a longitudinal study for the acquisition of leukemia-associated inhibitory activity (LIA) interactions after inoculation with Abelson virus in vivo. Within 2 to 4 days after virus infection, the granulocyte-macrophage colony-forming cells from the bone marrow and spleen of the infected mice became insensitive to inhibition by LIA, even though colony morphology appeared normal. Shortly after, or simultaneously with, the detection of the colony-forming cell resistance phenomenon, LIA was found in bone marrow, spleen, and thymus cells. The abnormal interactions appeared to be related to induction of lymphoma in BALB/c neonates and to a lymphoproliferative disease in adult BALB/c mice. In contrast, normal cellular interactions were noted in adult C57BL/6 mice which were not susceptible to the Abelson disease after virus inoculation and in untreated neonatal and adult BALB/c and adult C57BL/6 mice. Their colony-forming cells were sensitive to inhibition by LIA, and no LIA was detected in their bone marrow, spleen, and thymus cells. The abnormal cellular interactions are similar to those noted in human leukemia, lymphoma, and "preleukemia." This suggests that Abelson virus-infected mice can serve as a model for the study of LIA interactions.

A subpopulation of human polymorphonuclear neutrophils contains an active form of lactoferrin capable of binding to human monocytes and inhibiting production of granulocyte-macrophage colony stimulatory activities

Subpopulations of human peripheral blood polymorphonuclear neutrophils (PMN) differing in functional capacity were separated by a rosetting procedure by using rabbit IgG antibody-coated sheep erythrocytes (EA). EA+ and EA- populations of PMN both contained lactoferrin (LF) as determined by radioimmunoassay. However, only LF (10(-16) to 10(-6) M) obtained from EA+ (= FC receptor (FcR)+) PMN was able to suppress the production of granulocyte-macrophage colony stimulatory activity derived from human monocytes. LF from EA- PMN was inactive at concentrations as high as 10(-5) M. Extracts of EA- PMN contained proteolytic enzymes, not apparent in FcR+ PMN, that inactivated the inhibitory activity of LF obtained from FcR+ PMN. These results were substantiated by immunofluorescence studies. LF from FcR+ PMN bound to monocytes whereas LF from EA- PMN demonstrated negligible binding to the monocytes and extracts from EA- PMN drastically decreased the capability of LF obtained from FcR+ PMN to bind to monocytes. These studies demonstrate functional heterogeneity of peripheral blood PMN and suggest a role for PMN subpopulations in the regulation of myelopoiesis.

A subpopulation of human polymorphonuclear neutrophils contains an active form of lactoferrin capable of binding to human monocytes and inhibiting production of granulocyte-macrophage colony stimulatory activities

Subpopulations of human peripheral blood polymorphonuclear neutrophils (PMN) differing in functional capacity were separated by a rosetting procedure by using rabbit IgG antibody-coated sheep erythrocytes (EA). EA+ and EA- populations of PMN both contained lactoferrin (LF) as determined by radioimmunoassay. However, only LF (10(-16) to 10(-6) M) obtained from EA+ (= FC receptor (FcR)+) PMN was able to suppress the production of granulocyte-macrophage colony stimulatory activity derived from human monocytes. LF from EA- PMN was inactive at concentrations as high as 10(-5) M. Extracts of EA- PMN contained proteolytic enzymes, not apparent in FcR+ PMN, that inactivated the inhibitory activity of LF obtained from FcR+ PMN. These results were substantiated by immunofluorescence studies. LF from FcR+ PMN bound to monocytes whereas LF from EA- PMN demonstrated negligible binding to the monocytes and extracts from EA- PMN drastically decreased the capability of LF obtained from FcR+ PMN to bind to monocytes. These studies demonstrate functional heterogeneity of peripheral blood PMN and suggest a role for PMN subpopulations in the regulation of myelopoiesis.

Abnormal responsiveness of granulocyte-macrophage committed colony-forming cells from patients with chronic myeloid leukemia to inhibition by prostaglandin E1

The formation of myeloid colonies in soft-agar cultures of normal human marrow was markedly inhibited by prostaglandin E. Morphological characterization of colonies in the presence or absence of prostaglandin E1 showed that inhibition was restricted to monocytoid rather than neutrophil differentiation. Myeloid colony formation by granulocyte-macrophage-commited colony-forming cells from patients with chronic myeloid leukemia was not inhibited even by high concentrations of prostaglandin E and was independent of colony morphology. The altered sensitivity of leukemic colony-forming cells to prostaglandin E was observed at all stages of the disease and persisted following chemotherapy-induced reversion to a partial or complete Philadelphia chromosome-negative bone marrow status. This evidence suggests that altered myeloid stem cell sensitivity to a normal regulatory factor may play a role in the pathophysiology of chronic myeloid leukemia.

Continuous human bone marrow culture: Ia antigen characterization of probable pluripotential stem cells

The presence of Ia-like antigens on human CFU-C and BFU-e is confirmed and a cell type that lacked immediate capacity for granulocytic colony formation but generated CFU-c after brief incubation in simple suspension culture is identified. This pre-CFU-c, and its immediate progeny, was extremely sensitive to killing by anti-Ia serum with complement. In contrast, anti-Ia serum plus complement treatment of human bone marrow, while eliminating 93%-97% of all CFU-c and BFU-e, did not prevent the rapid regeneration of these progenitor cells and their production for some weeks under the conditions of continuous marrow culture. These studies suggest that the human equivalent of the pluripotential stem cell can replicate for some weeks in culture and generate committed progenitors, such as CFU-c and BFU-e. Furthermore, it would appear that Ia-like antigen is absent on the pluripotential stem cell, is rapidly gained as commitment to the various progenitor cell types occur, and is subsequently lost as these latter undergo differentiation within the marrow.

Expression of DR antigens on early human progenitors of neutrophilic and eosinophilic colonies in diffusion chambers (CFUd)

Incubation of the non-adherent low density cells from normal human bone marrow with an antiserum to DR antigens markedly inhibited their capacity to form granulocytic colonies in fibrin clot diffusion chambers implanted intraperitoneally into irradiated mice. The inhibitory effect of antiserum was abrogated after absorption of antiserum with B cells. Inhibition was obtained both with and without complement treatment. Neutrophilic colony formation exhibited a higher sensitivity to diluted antiserum to DR antigens as compared with eosinophilic colony formation. These results suggest that DR determinants are expressed on the neutrophilic and eosinophilic progenitor cells (CFUd) which give rise to colonies in diffusion chambers.

Specific inhibitory activity against granulocyte-progenitor cells produced by non-T lymphocytes from patients with neutropenia

Bone marrow and peripheral blood cells of patients with non-leukemic neutropenia contain and elaborate a granulocyte-progenitor cell inhibitory activity. The inhibitory activity is common to the neutropenias of the various etiologies studied, which included congenital, idiopathic, autoimmune, cyclical, common variable immuno-deficiency with hypogammaglobulinemia and drug induced states. It derives from non-adherent, low density, slowly sedimenting and non-E-rosetting cells and appears to require RNA and protein synthesis, but not cell division, for its production. The material is not species specific, inhibits autologous and allogeneic normal CFUgm and leukemic CFUgm, is not cell-cycle specific in action and is most effective against granulocyte colony forming cells (CFUg), less effective against mixed granulocyte-macrophage colony forming cells (CFUgm) and least or non-effective against macrophage colony forming cells (CFUm). This inhibitory activity has no influence on cells which generate CFUc in suspension culture or on the erythroid colony forming (CFUe) and burst forming (BFUe) units. It is different from other known inhibitory activities such as lactoferrin, leukemia inhibitory activity, E type prostaglandins, interferon and immunoglobulins. This inhibitory activity, while at present an in vitro phenomenon, may be produced as a secondary response within a compromised host.

Lactoferrin acts on Ia-like antigen-positive subpopulations of human monocytes to inhibit production of colony stimulatory activity in vitro

The relationship between Ia-like antigens (Ia-antigens) on human monocytes and the ability of lactoferrin (LF) to inhibit the production of colony stimulatory activity (CSA) for granulocyte and macrophage colony formation was investigated. Complement-dependent cytotoxicity of human monocytes by antiserum to Ia-antigen-reduced CSA production by 50%. LF decreased CSA production by monocytes but had no influence on monocytes insensitive to anti-Ia and complement. Anti-Ia in the absence of complement had no effect on production of CSA but blocked the inhibitory action of LF. This suggsts that LF inhibits production of CSA from an Ia-antigen-positive subpopulation of human blood monocytes. This may be of relevance to the regulation of myelopoiesis.

Specificity of lactoferrin as an inhibitor of granulocyte-macrophage colony-stimulating activity production from fetal mouse liver cells

Fetal mouse liver cultures capable of producing both erythropoietin (Ep) and granulocyte-macrophage colony stimulating activity (GM-CSA) were used to study the specificity of lactoferrin as an inhibitor of the production of GM-CSA. Both a granulocyte-derived colony-inhibiting activity (CIA) and lactoferrin inhibited GM-CSA production while having no effect on Ep production. These results demonstrate the specificity of lactoferrin for GM-CSA production.

Persistence of inhibitory activity against normal bone-marrow cells during remission of acute leukemia

Bone-marrow cells from patients with acute leukemia in remission were tested for their capacity to produce a substance (leukemia-associated inhibitory activity, LIA) that inhibits the formation of granulocyte and macrophage colonies in cultures of normal, but not of leukemic, bone marrow. LIA was detected in extracts of whole marrow in only eight of 83 patients in remission. However, extracts of slowly sedimenting cells, separated by velocity sedimentation from the marrows of eight patients in remission whose whole marrow had produced no LIA, produced inhibitory material in all cases. Extracts of the more rapidly sedimenting cells from these marrows contained an inactivator of LIA. Three of six patients in remission whose unfractionated marrow was unresponsive to LIA had a subpopulation of colony-forming cells that was sensitive to the inhibitor. These observations suggest that certain cellular functions dot not completely return to normal during remission of acute leukemia.

Regulation of macrophage and granulocyte proliferation. Specificities of prostaglandin E and lactoferrin

Hemopoietic colony-forming cells committed to macrophage differentiation (M-CFC) are selectively and differentially inhibited by prostaglandin E (PGE). A hierarchy of sensitivity was observed among murine CFC stimulated by colony-stimulating factors (CSF) which differ in their ability to initiate proliferation of morphologically distinct colony types, or stimulated by CSF provided by macrophage feeder layers. Inhibition of macrophage colony formation to 50 percent levels occurred with PGE concentrations between 10(-8) and 10(-9) M, and was still evident at 10(-10) -10(-11) M PGE concentrations. The growth of mixed colonies containing both macrophages and neutrophils was less sensitive to the inhibitory effects of PGE, however, the monocytoid component of these colonies was reduced in the presence of PGE. Neutrophil progenitor cell proliferation was not influenced by PGE concentrations below 10(-6) M, regardless of time of addition of PGE, whereas clonal macrophage expansion, as well as clone size, was sensitive to inhibition by PGE when added as late as 3 d after culture initiation. Prostaglandin F(2alpha), was not inhibitory to colony formation. Experimental evidence for a selective role of macrophage PGE in the regulation of macrophage colony formation was directly provided by utilizing resident peritoneal macrophages as a source of CSF for bone marrow target cell overlays. Simultaneous morphological analysis of colonies proliferating in bilayer culture in response to increasing concentrations of macrophages, and direct measurements of PGE synthesized by an identical number of macrophages maintained in liquid culture demonstrate that a specific decline in macrophage colony formation occurs coincident with a linear increase in macrophage PGE synthesis. Inhibition of macrophage PGE synthesis by indomethacin results in the specific enhancement of macrophage colony formation. Furthermore, macrophage PGE synthesis is induced by CSF preparations with the selective capacity to differentially stimulate macrophage proliferation, but not by those which preferentially stimulate granulocyte colony formation. In comparison to the effects of PGE on M-CFC, polymorphonuclear granulocyte-derived lactoferrin (LF) reduces macrophage production of colony-stimulating activities for macrophage, mixed macrophage- neutrophil and neutrophil colony formation. The ability of LF to reduce macrophage PGE synthesis, presumably by decreasing CSF production, suggests that LF and PGE can interact in the control of macrophage and granulocyte proliferation.

Oscillations of granulocytic and megakaryocytic progenitor cell populations in cyclic neutropenia in man

The concentration of granulocytic progenitor cells in the bone marrow of 2 patients with cyclic neutropenia was assessed at intervals during the cycle. Syncroneous oscillations were observed for cells forming neutrophilic and megakaryocytic colonies in diffusion chambers in vivo (CFU-D), suggesting a close relationship between the two cell types. However, an almost reverse relationship was observed between CFU-D and cells forming colonies in agar culture in vitro (CFU-C), which cycled out of phase with CFU-D. This supports the concept that CFU-D and CFU-C denote different cell types.

Colony-forming units in diffusion chambers (CFU-d) and colony-forming units in agar culture (CFU-c) obtained from normal human bone marrow: a possible parent-progeny relationship

An series of experiments was performed to elucidate the relationship between cells that form granulocytic colonies in fibrin clot diffusion chambers implanted into the peritoneum (i.p.) of irradiated mice (CFU-d) and day 7 and day 14 CFU-U which give rise to colonies after 7 and 14 days in agar cultures in vitro, respectively. Normal human bone marrow cells were cultured in suspension in vitro or in diffusion chambers implanted into irradiated or non-irradiated mice. During these culture conditions there was an initial decrease in the number of CFU-c per culture. This was followed by an increase between day 2 and day 7 of culture. No similar increase of neutrophilic CFU-d was observed. When CFU-d, day 14 and day 7 CFU-c in normal marrow were separated by velocity sedimentation and cultured in suspension culture or in diffusion chambers for 7 days, the maximum increase of day 7 and day 14 CFU-c was observed in slowly sedimenting cell fractions which contained the majority of CFU-d. After 3 days in suspension culture, the maximum increase of day 14 CFU-c was found in fractions which also gave rise to maximum numbers of CFU-c after 7 days. However, day 7 CFU-c were found in fractions which initially contained the majority of day 14 CFU-c. No increase in CFU-d was found in fractions initially containing peak numbers of CFU-c. Between 53 and 71% of CFU-c harvested from diffusion chambers in irradiated mice or from suspension cultures were sensitive to pulse incubation with tritiated thymidine, suggesting that the cells were proliferating during these culture conditions. In diffusion chambers implanted into non-irradiated mice, however, CFU-c were found to be relatively resistant to this treatment (3-11% sensitive to tritiated thymidine). Thus marked increases in CFU-c were also observed during experimental conditions, where no significant DNA synthesis was detected. A reproducible time sequence of increase in CFU-c populations in culture was observed. Day 14 CFU-c and cells that gave rise to clusters on day 7 in agar increased between day 2 and day 4, whereas day 7 CFU-c increased between day 4 and day 7. The results suggested that CFU-d gave rise to CFU-c in culture and that day 14 CFU-c were precursors of day 7 CFU-c.

Communication between white cells and the abnormalities of this in leukemia

The production of white blood cells is mediated by cellular communication. Proliferation and differentiation of granulocytic and monocytic progenitor and immature cells have been studied in detail and are regulated by stimulatory and inhibitory molecules produced and released from the progeny of the progenitor cells. The resultant interactions between cells and cell-derived molecules suggest operable positive and negative feed-back mechanisms during normal hematopoiesis, and what one sees in the end is the net result of these interactions. The complexities of cellular regulation are partially unravelled by physical separation of the different populations and biochemical analysis of the regulatory molecules. Subpopulations of granulocyte-monocyte progenitors (CFU-c) exist and evidence suggests that they vary in responsiveness to different molecules. Stimulatory molecules are themselves chemically and physically heterogenous and, until recently, believed to have similar biological actions, but this concept must be re-evaluated. Different molecules may activate different subsets of progenitor cells, and there is now a role for substances which enhance the stimulatory interactions. Many studies on normal and leukemic cell responsiveness to stimulation must be re-examined in light of this recent information. Several inhibitory substances operate during normal hematopoiesis. Mature granulocytes, progeny of CFU-c, appear to elaborate at least two inhibitory activities. One activity influences immature, recognizable granulocytes and the other indirectly reduces progenitor cell proliferation by decreasing the production and release of molecules which stimulate CFU-c. In addition, mononuclear phagocytes produce and release E-type prostaglandins in direct response to elevated levels of the stimulatory molecules and E-type prostaglandins counteract increased stimulatory levels by decreasing the sensitivity of CFU-c to stimulators. Much of our present level of sophistication derives from in vitro experimentation and it is apparent that we are only beginning to understand these inter-relationships and their relevance to the in vivo situation. However, these in vitro studies have shed light on the interactions occurring during leukemia. Leukemic cells retain the capacity to respond to normal regulators and must therefore be considered dependent rather than autonomous neoplasms. Abnormalities do exist in leukemic cell interactions: the progenitor cells themselves may be defective and leukemic cells may respond to molecules which normal cells do not. The degree of sensitivity to stimulators and inhibitors will have to be carefully investigated to determine if and what differences may exist between normal and leukemic cells. Normal mature granulocyte derived inhibitory activity is quantitatively deficient in leukemic cells but another inhibitory activity which appears to be specifically present in cells from patients with leukemia and some cases of myelodysplasia is present...

Identification of lactoferrin as the granulocyte-derived inhibitor of colony-stimulating activity production

Lactoferrin (LF), the iron-binding protein present in the specific granules of mature granulocytes has been identified as colony inhibitory factor (CIF) which suppresses granulocyte--macrophage colony stimulating activity (CSA) production by monocytes and macrophages in vitro and rebound granulopoiesis in vivo. Separation of LF and CIF by isoelectric focusing confirmed that the regions of inhibitory activity corresponded in both to a pH of congruent to 6.5. In addition, the purified immunoglobulin fraction of rabbit anti-human LF antiserum, but not rabbit anti-transferrin (TF), inactivated the capacity of LF and CIF to inhibit CSA production, an effect blocked by prior incubation of anti-LF with neutralizing concentrations of LF. Suppression of CSA production correlated with the iron-saturation of LF; APO-LF (depleted of iron) was only active concentrations greater than 10(-7) M, native LF (8% iron saturated) was active at 10(-15) M, and fully iron-saturated LF inhibited at 10(-17) M. Suppression of CSA production occurred within a 1/2-h preincubation period with human blood monocytes but was reversed by bacterial lipopolysaccharide (LPS). This reversal was dependent on the relative concentrations of LF to LPS. Serum TF, a biochemically similar iron-binding protein which is antigenically distinct from LF, was only minimally active at concentrations greater than 10(-6) M. LF did not inhibit exogenously stimulated human granylocyte and macrophage colony-forming cells or erythropoietin-dependent human or murine erythroid colony- or erythroid burst-forming cells. Microgram quantities of LF acted in vivo to inhibit rebound granulopoiesis and CSA production in CD1 and C57Bl/6 mice pretreated with cyclophosphamide. These results strongly implicate LF as a physiological regulator of granulopoiesis.

Inhibition of human erythropoietic colony formation in culture by treatment with Ia antisera

Incubation with Ia antiserum, followed by complement, markedly inhibited erythroid colonies arising from hematopoietic cells present in the nonadherent low density fractions of normal bone marrow. Both erythropoietin-dependent colonies and bursts were eliminated at dilutions of antiserum equivalent to, or greater than the dilutions required to abolish the granulocyte-macrophage colony formation. The inhibitory effect of the Ia antiserum was abolished by absorption with B but not T cells from lymphoid lines. Available evidence suggested that Ia determinants are expressed on the erythropoietin-sensitive progenitors of the erythroid series in precise analogy to their sequence of expression on the granulocyte lineage. In both lineages, as shown previously, the Ia determinants become undetectable during subsequent stages of differentiation.

Corticosteroids block newly induced but not constitutive functions of macrophage cell lines: myeloid colony-stimulating activity production, latex phagocytosis, and antibody-dependent lysis of RBC and tumor targets

Hydrocortisone at 10(-4) M added to macrophage cell lines had no effect on the following activities: J774.1 antibody-dependent phagocytosis and lysis of sheep RBC, RAW 264 antibody-dependent lysis of tumor targets, latex bead phagocytosis by PU5-1.8 cells, and constitutive production of myeloid colony-stimulating activity (CSA) by WEHI-3 cells. In contrast, 10(-4) M hydrocortisone completely inhibited LPS or PPD activation of the following functions: induced production of myeloid CSA, stimulation of latex phagocytosis and stimulation of antibody-dependent lysis of tumor targets by PU5-1.8 cell line, and stimulation of antibody-dependent lysis of RBC targets by RAW 264 cell line. Lower concentrations of hydrocortisone or dexamethasone at 10(-6) M inhibited the LPS induction of CSA from 55 to 90%. Growth inhibition of PU5-1.8 cells caused by 1 microgram/ml LPS was also partially reversed by corticosteroids. Thus, steroids block these newly induced but not constitutive functions of these macrophage cells in culture.

Induction of myeloid colony-stimulating activity in murine monocyte tumor cell lines by macrophage activators and in a T-cell line by concanavalin A

Certain fibrosarcoma lines in culture and the WEHI-3 myelomonocytic leukemia cell line have previously been shown to secrete myeloid colony-stimulating activity (CSA) spontaneously. We describe here other hematopoietic tumor cell lines in which CSA is either produced constitutively or inducible by immunostimulators. CSA production in macrophage and monocyte tumor lines is induced by lipopolysaccharide, zymosan, Mycobacterium strain Bacillus Calmette-Guérin, tuberculin purified protein-derivative preparation from mycobacteria, and dextran sulfate. Myeloma, mastocytoma, and T-lymphoma lines do not produce CSA with or without these agents. In contrast, the T-lymphocyte mitogen concanavalin A (but not phytohemagglutinin) induces CSA synthesis in one of seven T-lymphomas tested. In most cases induction of CSA is correlated with conditions of cell growth inhibition by the immunomodulators. However, other drugs that cause cytostasis or cytotoxicity do not lead to CSA production. Leukemic cells thus may retain sensitivity to normal regulatory events with resultant effects on host hematopoietic cell functions.

Immunologic functions and in vitro activation of cultured macrophage tumor lines

Five murine monocyte of macrophage tumor lines adapted to culture were characterized for differentiated properties. They ingested zymosan and latex beads, bore receptors for immunoglobulin and complement, synthesized lysozyme (most of which was secreted), and produced granulocyte colony-stimulating activity, either spontaneously or inducibly. Some of the lines also mediated phagocytosis and exocytosis of red blood cells (RBC) and lysis of tumor targets, dependent on the presence of specific antitarget sera. All the lines were growth inhibited by zymosan and Mycobacterium bovis BCG, but not by latex beads. Other macrophage-activating agents, dextran sulfate and lipopolysaccharide (LPS), as well as tuberculin purified protein derivative (PPD), inhibited most of the lines. Except for Fc and C receptors, most of the above properties were not found with other types of hematopoietic tumors in culture. In attempts to activate the macrophage lines in vitro to the "angry" state, we found that preincubation with concentrations of LPS and PPD cytostatic to the cells stimulated antibody-dependent RBC lysis, but not antibody-independent or tumor cytolysis. A classification of monocyte-related tumors and normal cells is proposed based on functional activities and differential sensitivity to immunostimulating agents.

Inhibition in vivo of mouse granulopoiesis by cell-free activity derived from human polymorphonuclear neutrophils

Cell-free extracts from human polymorphonuclear neutrophils (PMN) inhibited rebound granulopoiesis in the bone marrow and spleen of mice pretreated with cyclophosphamide to remove endogenous PMN. Absolute numbers of granulocytemonocyte progenitor cells (CFU-C) and net endogenous colony-stimulating activity (CSA) production were found to be increased 3 days after cyclophosphamide in the bone marrow and 6 days after in the spleen. Administration of PMN extract to the drug-treated mice prior to rebound granulopoiesis substantially decreased CSA production and CFU-C but not spleen B lymphocyte colony-forming cells. In addition, mice treated with PMN extract had decreased levels of CSA in serum and in conditioned medium of marrow-free bone, heart, and lung cultures. Inhibition was reversed by injection of bacterial lipopolysaccharide. Extracts from PMN of patients with chronic myelogenous leukemia, inactive in vitro, had no effect in vivo. These results demonstrate that inhibitory activity derived from PMN can control granulopoiesis in vivo.

Isolation of a granulocyte colony inhibitory factor derived from human polymorphonuclear neutrophils

An inhibitory factor obtained from mature human granulocytes which suppresses granulocyte and monocyte-macrophage colony formation by an action on the endogenous colony stimulating factor-producing cells has been partially purified and characterized. The methods for purification consisted of a combination of ultracentrifugation, DEAE-Sephadex chromatography, SDS polyacrylamide gel electrophoresis and isoelectric focusing. The material had a molecular weight range of 102--128 000 and an isoelectric point between pH 6.2 and 6.4. The inhibitory factor was found to be heat stable and glycoprotein in nature.

Limitation of excessive myelopoiesis by the intrinsic modulation of macrophage-derived prostaglandin E

The clonal proliferation of the committed granulocyte-macrophage stem cell is controlled by a balance between mutually opposing factors, colony stimulating factor and prostaglandin E, both of monocyte-macrophage derivation. Increases beyond a critical concentration of colony stimulating factor within the local milieu of the mononuclear phagocyte induces the coincident elaboration of prostaglandin E, a self-regulated response which serves to limit the unopposed humoral stimulation of myelopoiesis.

In vitro regulation of a mouse myelomonocytic leukemia line adapted to culture

Regulation of the growth and production of granulocyte colony-stimulating activity (CSA) by WEHI-3 cells, a lysozyme-secreting mouse cell line adapted to culture, was investigated in vitro. WEHI-3 cloning efficiency is not enhanced by exogenously added CSA. However, WEHI-3 cloning efficiency in agar was suppressed by an activity in human polymorphonuclear neutrophil extract (colony-inhibiting activity) which inhibits endogenous WEHI-3 CSA production. The addition of increasing concentrations of WEHI-3- or L cell-conditioned medium containing CSA to CIA-depressed WEHI-3 agar cultures resulted in graded increases of cloning efficiency to that of the untreated sample. Testosterone, Deca-Durabolin, and bacterial lipopolysaccharide increased production of CSA by WEHI-3 cells and overcame colony-inhibiting activity-mediated suppression of CSA production, even when activating agents were added 1 day after the addition of colony-inhibiting activity. The activating agents had no direct stimulatory effect on normal mouse marrow colony-forming cells and did not enhance CSA activity. WEHI-3 cells respond to growth inhibitory and stimulatory activities and can serve as an in vitro model for studying the regulation of neoplastic cells.

Expression of Ia-like antigen molecules on human granulocytes during early phases of differentiation

Human B lymphocyte antigens analogous to the murine Ia determinants were found on myeloblasts and promyelocytes but not on more mature granulocytes. This was apparent by fluorescent staining with both human alloantisera and rabbit antisera to the isolated Ia-like proteins. The cells of patients with chronic myelocytic leukemia showed this difference especially clearly. Separation of the myeloblasts and promyelocytes by multistep density gradient fractionation produced a marked enrichment of the positive cells. The remaining cells from higher density fractions were more-mature neutrophils that were essentially negative. In acute myeloid leukemia, in which myeloid cells early in differentiation predominate, the vast majority of cells were strongly positive. Similar results were obtained with normal bone marrow cells. Here also, only the early forms of the myeloid series separated by gradient centrifugation had Ia antigens. Evidence was also obtained for the presence of Ia determinants on cells with the appearance of early erythroid precursors. Support for the presence of the Ia determinants on granulocyte-macrophage committed stem cells was provided by the inhibition of granulocyte colony formation in agar cultures following preincubation of normal bone marrow with antiserum and complement. Cross absorptions with purified preparations of immature cells provided evidence for the close similarity of the antigenic determinants on both myeloblasts and B cells. A 28,000-37,000-dalton bimolecular complex obtained from myeloblast membranes contained the Ia determinants and was similar to that obtained from peripheral blood B cell membranes.

Immunostimulators induce granulocyte/macrophage colony-stimulating activity and block proliferation in a monocyte tumor cell line

Monocyte tumor cell line PU5-1.8 does not normally produce colony-stimulating activity (CSA) required by granulocyte and macrophage progenitors to proliferate and mature in agar. However, CSA is induced in the culture line by as little as 10 ng/ml endotoxic lipopolysaccharide (LPS), with maximum CSA production and release to the medium between 2 and 3 days of incubation. Derived lipid A, but not alkali-treated LPS, is also active. Induction requires RNA and protein synthesis, but is not blocked by mitomycin C or Colcemid. Other inducers of CSA include Mycobacterium Bacillus Calmette-Guérin, tuberculin protein preparation purified protein derivative, zymosan, and phorbol myristate. All inducing agents are specific inhibitors of the monocyte tumor cell proliferation in vitro. Latex beads, another macrophage-activating agent, are rapidly phagocytosed by PU5-1.8 cells, but neither inhibit growth nor induce CSA.

Cell-free granulocyte colony inhibiting activity derived from human polymorphonuclear neutrophils

Human PMN (non-adherent: density greater than 1.070 g/cm3) were used to prepare cell-free colony inhibiting activity (CIA). Intact PMN, PMN conditioned media (serum-free or serum-containing) and supernatant from immediately lysed PMN equally reduced the numbers of spontaneous bone marrow (density less than 1.070 g/cm3; depleted of PMN) colonies and clusters. Addition of CIA reproducibly reduced colony and/or cluster numbers by 35-70%. CIA was heat labile being inactivated at 37 degrees C. Daily additions of CIA reduced colony numbers even further; inhibition was dependent on [PMN] used to prepare CIA and on the potency of stimulation produced by colony stimulating cells (CSC). PMN from some patients with leukemia were inactive as inhibitors and did not condition media with CIA. All experiments were thereafter controlled by parallel assessment of supernatant of lysed PMN not demonstrating any CIA. CIA appears to be not only stored in PMN but released from viable, as well as degranulating PMN. Although not species-specific, CIA was specific in its nontoxic action on CSC; colony forming cells and cell-free colony stimulating activity were not affected. The influence of CIA on CSC could be reversed within 10 minutes, but not within 35 minutes of incubation. CIA may have possible physiological relevance.

In vitro regulation of granulopoiesis in human leukemia: application of an assay for colony-inhibiting cells

We describe two assays to detect the action of colony-inhibiting cells. In the first assay, we used a simple density separation technique to remove dense neutrophils (PMN) from suspensions of blood and of bone marrow cells prior to culture in semisolid agar. Conditions were arranged to ensure that control suspensions of unseparated cells and test suspensions of buoyant mononuclear cells differed only in their content of neutrophils. The control and test suspensions contained equal numbers of mononuclear cells (and granulocyte precursors). Colony (and cluster) formation was invariably enhanced in neutrophil-depleted cultures of normal cells. In the second assay, dense PMN, treated by an adherence separation procedure, were recovered, and the non-adherent dense PMN were added back to PMN-depleted cultures. A reproducible dose-related decrease in colony (and cluster) formation to basal levels resulted. The inhibitory effect was identical when the PMN were added directly to the culture (overlayer) or to the underlayer. In PMN-depleted cultures obtained from patients with leukemia and other hemopoietic disorders, neither colony nor cluster formation was enhanced, and sometimes it was reduced. When we compared the effect of adding patient and normal non-adherent PMN to target cultures of normal and patient PMN-depleted cells, some leukemic PMN were noninhibitory. Our results suggest that abnormalities of cellular interactions in vitro detected in the first assay may have more than one explanation, as shown when they are subjected to the closer scrutiny possible with the second assay.

Relationship of colony-stimulating activity to apparent kill of human colony-forming cells by irradiation and hydroxyurea

Suspensions of human bone marrow cells were subjected to 137Cs irradiation in vitro and then cultured in semisolid agar medium. Cultures of irradiated cells were stimulated with colony-stimulating activity (CSA) of different potencies, and it was found that the amount of stimulation applied to cultures influenced the apparent kill of colony-forming cells (CFC). It was also found that the effects of irradiation on colony formation were not confined to CFC kill since medium conditioned by cells during irradiation exhibited stimulatory and inhibitory properties after treatment by 600 and 1000 rads, respectively. Studies in which irradiated cells were pretreated with hydroxyurea indicated that CFC in the DNA synthetic phase of the cell cycle were particularly sensitive to low doses of irradiation. The proliferative capacity of CFC surviving 1000 rads was undiminished as judged by their ability to form large colonies. Estimates of CFC kill by hydroxyurea were also affected by the level of CSA.

Granulopoiesis in "preleukemic" mice with anemia induced by Rauscher leukemia virus, variant a

To understand further the hematopoietic dyscrasias induced by a variant (a) of Rauscher leukemia virus (RLV), we used Escherichia coli endotoxin to stress the hematopoietic system of control and RLV/a-infected BALB/c mice. During the preleukemic stages of virus infection, there was slight splenomegaly without peripheral blood erythroblastosis. Granulocyte release and tissue mobilization mechanisms appeared unaffected by the RLV/a infection. Both RLV/a-infected and control mice reacted to endotoxin with peripheral granulocytosis and peritoneal granulocyte mobilization, though the circulating granulocyte levels in RLV/a-treated mice initially were lower than those in controls. Spleen of RLV/a-infected animals were larger than those of controls, but both responded to endotoxin with elevated numbers of granulocytes and erythroblasts. Since numbers of bone marrow erythroblasts in both groups of mice were decreased after endotoxin, stem cell competition and/or shunting of stem cells from marrow to spleen may have been involved. Endotoxin also induced rapid falls in hematocrit levels in both groups. These studies suggested that RLV/a-infected mice can be a model to study 1) erythropoietic dysfunction uncomplicated by defective granulopoietic release and tissue mobilization control mechanisms, and 2) progression of evolving granulocytic leukemia.

Control of granulopoiesis in man.III. inhibition of colony formation by dense leukocytes

Cellular feeder layers, prepared from normal blood leukocytes, usually stimulate human marrow to form colonies. A significant increase in the stimulating activity of unseparated leukocyte feeder layers is brought about following the removal of dense leukocytes in a manner which avoids enrichment of any remaining cell type. Restoration of dense leukocytes to a dense leukocyte depleted leukocyte feeder layer results in the reduction of stimulating activity to that of an unseparated leukocyte feeder; however, addition of dense leukocytes to unseparated leukocyte feeder layers has no effect on the stimulatory activity, over the range of concentrations used in this study.

Studies on control of granulopoiesis in man. I. Relationship of leukocyte colony-stimulating activity in vitro to neutrophil count in vivo

We examined the relationship of leukocyte colony-stimulating activity (CSA) in vitro to neutrophil count in vivo. Using a standard two-layer system, cultures of 10(6) leukocytes were assayed for their ability to stimulate colony formation by human bone marrow colony-forming cells. The total leukocyte CSA per ml (TLCSA) of blood varied directly with the blood neutrophil count in a group of patients with a wide range in blood neutrophil count, and in two patients recovering from neutropenia in whom serial observations were made. In the latter two patients the rise in TLCSA did not antedate the rise in blood neutrophil count, suggesting that blood leukocyte colony-stimulating factor (CSF) per se probably has little biologic significance. However, release into the circulation of cells which generate CSF could be an important way of controlling the amount of CSF acting within the marrow. In one patient the CSA of dialyzed serum increased after the rise in TLCSA, while undialyzed serum contained no CSA.