Establishment and characterization of a human acute monocytic leukemia cell line (THP-1)

Molecular cloning of a gene selectively induced by gamma interferon from human macrophage cell line U937

A cDNA clone encoding a gamma interferon (IFN-gamma)-inducible mRNA in human cells of the macrophage lineage was isolated and characterized. The corresponding gene, gamma.1, was selectively induced by IFN-gamma, responding a hundredfold better to IFN-gamma than to IFN-alpha. The induction was rapid and transient, with maximal mRNA accumulation at about 3 h and decline to the basal level after 48 h. Transcriptional activation could be detected as early as 5 min after IFN-gamma stimulation and accounted entirely for the mRNA accumulation. The induction of gamma.1 by IFN-gamma was cell-type restricted, being seen only in macrophages and endothelial cells. In addition, phorbol ester-induced differentiation of promyelocytic HL-60 cells and promonocytic THP-1 cells rendered the gamma.1 gene inducible by IFN-gamma. The 1.0-kilobase gamma.1 cDNA sequence encoded a small predicted polypeptide of 38 amino acids and had a conserved sequence associated with rapidly turning over mRNAs. In vitro translation of the gamma.1 transcript yielded a 4,000-dalton polypeptide.

Increased monokines in cytomegalovirus infected myelomonocytic cell cultures

In an investigation of the role of monokines in CMV associated immunosuppression we document modulation of both TNF and IL-1 beta in CMV infected THP-1 cells. CMV infected cultures released almost two-fold more IL-1 beta protein and contained significantly higher IL-1 beta mRNA levels than uninfected cultures for 72-96 h after induction. In both CMV infected and uninfected cultures, significant amounts of IL-1 beta protein were not detected until 24 h post induction, while maximum amounts of TNF were detected in culture supernatants by 3 h post induction, suggesting that TNF may play a role in IL-1 beta induction. TNF levels subsequently declined but in infected cultures remained over 2.5-fold higher than controls through 96 h. The CMV alteration in the kinetics and extent of IL-1 beta release must be indirectly mediated by CMV since only 1% of THP-1 cells were infected. Most infected cells expressed CMV immediate early proteins but did not overexpress IL-1. We speculate that CMV infected cells release excess TNF or other stimulatory factors which increase IL-1 beta synthesis. Since IL-1 beta is increased, the decreased IL-1 'activity' described by others as an explanation in part for the immunosuppressive effects of infection may actually reflect alterations of IL-1 inhibitor levels during CMV infection.

The human lysozyme gene. Sequence organization and chromosomal localization

We have isolated two overlapping recombinant lambda-phage clones from a genomic lambda-EMBL3 library containing 25 kb of the human lysozyme gene region. Furthermore a full-lenght human lysozyme cDNA clone of 1.5 kb was isolated from a human placenta cDNA library. Nucleotide sequences of the entire structural gene and the cDNA clone were determined. The human lysozyme gene spans 5856 bp and its sequence organization with four exons and three introns is homologous to the chicken lysozyme gene and the human alpha-lactalbumin gene. Human and chicken lysozyme genes differ mainly in the size of their introns and 3' non-coding region. Four Alu repetitive elements were found in the human lysozyme gene, one in each intron and one on the fourth exon. Lysozyme transcripts of 1.6 kb and 0.6 kb in size were detected in human myeloid cell lines U-937, HL-60 and THP-1 and surprisingly in human hepatoma cell lines HepG2 and Hep3B. The lysozyme gene locus was assigned to human chromosome 12 by hybridization to a panel of DNAs from human-rodent somatic cell hybrids.

Identification of a monocyte specific pre-interleukin 1 beta convertase activity

Interleukin 1 (IL-1) is a lymphokine secreted by monocytes in response to a variety of inflammatory stimuli. IL-1 beta, the predominant form of IL-1 produced by human monocytes, is synthesized as an inactive precursor of 31 kDa and is cleaved at Asp116-Ala117 to yield a 17.5-kDa extracellular form. The exact cellular site of cleavage and mechanism of secretion is at present unknown. We have prepared cell-free postnuclear extracts from freshly isolated human monocytes as well as THP.1 cells, a human monocyte-like cell line, and various blood lymphocytes and fibroblast cell lines. Using pre-IL-1 beta synthesized by in vitro transcription and translation, we have shown that only extracts derived from human monocytes and THP.1 cells were capable of cleaving precursor IL-1 beta to authentic mature IL-1 beta. Subcellular fractionation of the extracts suggested that the processing activity is found in the cytosol of monocytes or monocyte-like cell lines. The cleavage product of this protease is identical to authentic IL-1 beta as shown by mobility on SDS/PAGE and amino acid sequence analysis of the [3H]leucine-labeled product. The cleavage product is also capable of binding to the IL-1 receptor found on fibroblast membranes. Finally, mutation of Asp116----Ala116 rendered the IL-1 beta precursor resistant to cleavage by the processing activity. We conclude that a protease activity found only in monocytes will specifically process IL-1 beta to an active form.

Optimal induction of tumor necrosis factor production in human monocytes requires complete S-form lipopolysaccharide

Optimal activation of human monocytes in vitro for the biosynthesis of tumor necrosis factor was achieved only with complete S-form lipopolysaccharide. Endotoxin preparations with shorter carbohydrate chains or the lipid A component of lipopolysaccharide were not able to induce release of comparable amounts of tumor necrosis factor by monocytes under the conditions described. The same differences in the level of tumor necrosis factor mRNA were observed. Moreover, addition of these agents to appropriate monocyte-activating substances inhibited the production of tumor necrosis factor. The regulatory implications of this phenomenon are discussed.

Multiple effects of human recombinant interleukin 4 on human myeloid monocyte cell lines

The effects of recombinant human interleukin 4 (rIL-4) on proliferation and differentiation on human myeloid/monocytic leukemia cell lines were examined. At high concentrations, rIL-4 had a slight enhancing effect on [3H]thymidine incorporation by U937 cells. rIL-4 markedly induced expression of the Fc epsilon receptor (CD23) and the Leu-M3 antigen (CD14) on U937 cells. HL60 and THP-1 cells treated with rIL-4 also showed increased CD23 expression, but little change of CD14 antigen expression. CD23 induction required lower amounts of IL-4 than needed for T cell growth, indicating that CD23 induction on U937 will serve as a sensitive assay for human IL-4. rIL-4 reduced the steady state level of IL-1 beta mRNA in U937.

Augmentation of human cytotoxic T lymphocytes against autologous tumor by a factor released from human monocytic leukemia cell line

A human acute monocytic leukemia cell line, THP-1, releases a factor which activates human cytotoxic (killer) T lymphocytes (CTL) against autologous tumor in vitro. The factor, named cytotoxic (killer) T cell activating factor (KAF), is an acidic protein of 70,000 to 100,000 dalton molecular size. Peripheral blood leukocytes from two patients, bearing epithelioid sarcoma or malignant schwannoma, were cultured for 7 days with individual autologous tumor to induce CTL directed to the corresponding tumor. Monocyte-depleted peripheral leukocytes generated lesser CTL activity than the monocyte-containing leukocyte population. However, the KAF was able to replace the monocyte function. The KAF acted at the CTL generation phase as well as the effector phase. The KAF-activated killer cells possessed CD4-8+ surface phenotype. The CTL killed autologous tumor or other unrelated tumor cell lines only when they shared some of the HLA class I antigens. It was also demonstrated that the KAF does not activate killer cells without proper antigenic stimuli, because the KAF-augmented CTL possess specificity against autologous tumor or other HLA-A or -B matched tumor cell lines. The therapeutic applicability of human KAF for anti-tumor CTL therapy against autologous tumor is discussed.

Involvement of second messengers in regulation of the low-density lipoprotein receptor gene

Transcription of the low-density lipoprotein receptor (LDL-R) gene in the human monocytic leukemic cell line THP-1 and in the human hepatocarcinoma cell line Hep-G2 is regulated by second messengers of the diacylglycerol-protein kinase C (DAG-PKC), inositol 1,4,5-triphosphate-Ca2+, and cyclic AMP pathways. Exogenous phospholipase C (which releases DAG and inositol 1,4,5-triphosphate), PKC activators (phorbol esters and DAG), Ca2+ ionophores, and a cyclic AMP analog all transiently induced accumulation of LDL-R mRNA. The effects of these three signal-transducing pathways were to a large extent additive. Furthermore, PKC stimulation effected an increase in LDL binding, which suggested that the increase in LDL-R mRNA resulted in an increase in functional cell surface receptor activity. These results suggest that uptake of cholesterol by these cells is under control of both intracellular cholesterol levels and external signals.

Cloning and expression of the leukotoxin gene from Actinobacillus actinomycetemcomitans

The leukotoxin produced by Actinobacillus actinomycetemcomitans has been implicated in the etiology of juvenile periodontitis. To initiate a genetic analysis of the role of this protein in disease, we have cloned the leukotoxin gene in Escherichia coli. Recombinant colonies carrying toxin gene sequences were isolated by screening a genomic A. actinomycetemcomitans library with a DNA probe for the leukotoxin gene from a related bacterium, Pasteurella haemolytica. To demonstrate that the cloned A. actinomycetemcomitans DNA contained a functional leukotoxin gene, protein extracts of E. coli containing the A. actinomycetemcomitans clone were tested directly for leukotoxic activity against human cell lines in chromium release assays. A construct containing the entire cloned region produced a functional toxin. No cytotoxicity was seen when extracts from cells containing plasmids with deletions in the putative coding region were used. Furthermore, the toxin produced by the cloned gene has the same target cell specificity as the leukotoxin extracted directly from A. actinomycetemcomitans. These results indicate that sequences encoding a functional leukotoxin have been cloned and are expressed in E. coli. Southern blot analysis of DNA from leukotoxin-producing (Lkt+) and non-leukotoxin-producing (Lkt-) strains indicated that the Lkt- strain also contained a copy of the gene.

Molecular cloning of a gene selectively induced by gamma interferon from human macrophage cell line U937

A cDNA clone encoding a gamma interferon (IFN-gamma)-inducible mRNA in human cells of the macrophage lineage was isolated and characterized. The corresponding gene, gamma.1, was selectively induced by IFN-gamma, responding a hundredfold better to IFN-gamma than to IFN-alpha. The induction was rapid and transient, with maximal mRNA accumulation at about 3 h and decline to the basal level after 48 h. Transcriptional activation could be detected as early as 5 min after IFN-gamma stimulation and accounted entirely for the mRNA accumulation. The induction of gamma.1 by IFN-gamma was cell-type restricted, being seen only in macrophages and endothelial cells. In addition, phorbol ester-induced differentiation of promyelocytic HL-60 cells and promonocytic THP-1 cells rendered the gamma.1 gene inducible by IFN-gamma. The 1.0-kilobase gamma.1 cDNA sequence encoded a small predicted polypeptide of 38 amino acids and had a conserved sequence associated with rapidly turning over mRNAs. In vitro translation of the gamma.1 transcript yielded a 4,000-dalton polypeptide.

A growth-promoting factor for human myeloid leukemia cells from horse serum identified as horse serum transferrin

A growth-promoting factor for human myeloid cells was purified to apparent homogeneity from horse serum by a combination of gel filtration, blue Sepharose affinity chromatography, Mono Q anion-exchange chromatography, Mono P chromatofocusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The growth promoter was an iron-bound, single glycopolypeptide chain with a molecular weight of 84,000, an isoelectric point of 5.4 and an amino terminal sequence of Glu-Gln-Thr-Val-Arg-Trp-Cys-Thr-Val-Ser-Asn-His-Glu-Val-Ser-Lys-. According to the results of the amino acid sequence, iron binding ability and physicochemical properties, we identified the growth-promoting factor as horse serum transferrin. It was highly active in promoting the proliferation of a human monocytic leukemia cell line, THP-1, as well as of two other human myeloid cell lines, HL-60 and K-562. It had the same activity in proliferating THP-1 cells as 5% fetal calf serum-supplemented medium. Horse serum transferrin could be substituted for human or bovine serum transferrin.

High rate of HLA class II mRNA synthesis in rheumatoid arthritis joints and its persistence in culture: down-regulation by recombinant interleukin 2

The expression of HLA class II mRNA was investigated in the joints of patients with active rheumatoid arthritis (RA) in order to evaluate patterns of synthesis. Northern hybridization analysis showed that HLA class II gene transcripts in RA joints were of the correct sizes, and subsequent analyses were performed by slot blotting. All active RA samples expressed high levels of HLA-DR, DP, and DQ mRNA with DP and DQ less than DR. Synovial fluid or membrane cells, chiefly a mixture of T cells and macrophages, were placed in culture, in the absence of any stimulation. The levels of mRNA remained at a high level in vitro. The half of HLA-DR mRNA in joint cells was very brief (approximately 30 min), indicating that prolonged synthesis was due to restimulation of the cells. The effect of lymphokines on HLA class II regulation on joint cell was assessed. Gamma interferon was capable of augmenting HLA-DR to some extent, but paradoxically interleukin 2 at concentrations optimal for stimulating T cells, diminished HLA-DR expression.

Monoclonal antibody directed to human T-cell malignancy antigen

A murine monoclonal antibody (B2D) against a cultured pre-T acute lymphoblastic leukemia (ALL) cell line THP-6 has been produced. The antibody reacted with seven out of eight cultured T-ALL cell lines and with leukemic cells from three out of four T-ALL/lymphoma patients. The antibody did not react with normal T and B lymphocytes, monocytes, granulocytes, platelets, erythrocytes, bone marrow lymphoid-like precursor cells, thymocytes and other acute and chronic leukemic cells of non-T cell origin. Furthermore, B2D did not react with phytohemagglutinin-activated T cells nor with concanavalin A-activated T cells. The molecules immunoprecipitated with B2D had molecular weights of 50-55 kD. Thus, B2D seems to be highly specific for T-cell malignancies. These results show that B2D defines one of human leukemia antigens which are expressed on the cell surface of T-ALL cells. Monoclonal antibody B2D may be useful for the subclassification of T-ALL cells and has therapeutic potential for a certain type of T-ALL.

Human myeloid cells possessing high-affinity receptors for granulocyte-macrophage colony stimulating factor

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a glycoprotein which controls growth and differentiation of hemopoietic cells to form mature granulocytes and macrophages. The presence of specific high-affinity receptors for this factor on myeloid cell lines was investigated using radiolabelled recombinant human GM-CSF. Eight cell lines representing different stages of myeloid differentiation were examined. Equilibrium binding at 37 degrees C using different concentrations of 125I-GM-CSF and Scatchard Plot analysis was used to determine the equilibrium dissociation constant and the average number of receptors per cell. Low receptor numbers were found with an average of 74 on HL-60 cells and decreasing numbers on U-937, KG-1, X-376 and THP-1. Receptors were not detectable on RC-2A, CTV-2 and HEL cells. Other cell lines were also investigated including a Burkitt type ALL cell line, X-308 and a Hodgkin's tumor cell line, L 428 KSA. No receptors were detectable on these lines. Normal blood mononuclear cells were examined and indicated that more mature cells have a higher receptor density. Receptors were detectable on normal bone marrow cells but the nature and receptor density of the binding cells remains to be elucidated.

Inhibition of neutrophil chemotaxis by a monoclonal antibody (TM316)

A monoclonal antibody, TM316, IgM kappa, was raised against the human monocytoid leukaemia cell line THP-1, and was shown to inhibit polymorphonuclear leucocyte (PMN) chemotaxis. The molecular weight (MW) of the protein on the PMN membrane with which TM316 bound was about 78,000. TM316 inhibited the chemotactic response of human PMN induced by at least three kinds of chemotactic factors (activated serum, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP), and a lymphocyte-derived chemotactic factor (LDCF)) to the same extent. The extent of inhibition of chemotaxis by TM316 was strongly correlated with the quantity of cellular surface antigen recognized by TM316, when a cell sorter was used for analysis. TM316 did not alter the number of Fc or complement receptors of PMN, nor did it affect luminol-enhanced chemiluminescence (CL), lysosomal enzyme release, adherence, or superoxide anion generation by PMN. TM316 seemed to recognize a common surface antigen which was necessary only for the process of chemotaxis.

Differences in cytopathogenicity and host cell range among infectious molecular clones of human immunodeficiency virus type 1 simultaneously isolated from an individual

A cytopathic human immunodeficiency virus type 1 (HIV-1) isolate containing multiple virus genotypes was molecularly cloned, and the biological activity of six randomly selected clones was assessed by transfection into human lymphoid or glial cell lines. Five infectious clones of HIV-1, termed N1T-A through -E, were isolated in this manner. Clones N1T-A, -B, -C, and -E could be distinguished by restriction endonuclease mapping whereas clones N1T-B and -D had identical maps with the enzymes used. Each clone exhibited a distinct host cell range as well as markedly different infection kinetics and cytopathogenic properties when tested in human cell lines of T-lymphocytic, monocytic, and astrocytic origin. In particular, infection with HIV-1 clone N1T-E was characterized by slow kinetics and lack of significant cytopathic effects in acutely and chronically infected cells. Clone N1T-A, similar to the parental isolate N1T, exhibited a wide host cell range, fast kinetics of infection, and high cytopathogenicity. These data indicate that HIV-infected individuals may carry multiple HIV-1 genotypes with distinct cytopathogenic potential and cell tropism. Analysis of virus isolates must take into account the contribution, or masking, of individual virus clones.

Oligospecificity of the cellular adhesion receptor Mac-1 encompasses an inducible recognition specificity for fibrinogen

Mitogenesis, cellular aggregation, and motility follow upon the interaction of fibrinogen with certain defined cell surface receptors. In addition to circulating platelets and vascular endothelium, monocytes express what appears to be a receptor for fibrinogen. Evidence is presented here that the leukocyte adhesion receptor Mac-1 can be specifically induced to bind fibrinogen with characteristics immunochemically and functionally distinct from the established Arg-Gly-Asp-directed fibrinogen receptors. The competence of Mac-1 as a fibrinogen receptor is a general property of cells of monocyte and myeloid lineage acquired after maturational changes of some regions of the alpha subunit of Mac-1 during the process of cell differentiation. This ligand recognition specificity of Mac-1 is lacking for the resting cell. Rather, induction of fibrinogen binding capacity of Mac-1 is due to a cellular response to selected agonists characterized by inducing rapid transients of cytosolic Ca2+. Although different in activation pathways and recognition specificity, Mac-1 exhibits an oligospecific ligand versatility characteristic of other homologous Arg-Gly-Asp-directed adhesion receptors.

Post-transcriptional control of IL-1 gene expression in the acute monocytic leukemia line THP-1

The acute monocytic leukemia cell line THP-1 secretes predominantly IL-1 beta after treatment with bacterial lipopolysaccharide and tumour promoting phorbol ester (PMA). IL-1 alpha is also secreted, but represents less than 10% of the total IL-1 activity. This differential is reflected at the level of mRNA as IL-1 beta mRNA is more abundant than IL-1 alpha mRNA. Studies of transcription in isolated nuclei however indicate that each gene is transcribed at a similar rate, suggesting that post-transcriptional mechanisms regulate the relative abundance of IL-1 alpha and IL-1 beta mRNA. Measurement of RNA half life after addition of alpha-amanitin (an inhibitor of RNA polymerase II) indicate that IL-1 alpha mRNA is not as stable as IL-1 beta mRNA suggesting one mechanism for the different relative levels of RNA.

Adhesive receptor Mac-1 coordinates the activation of factor X on stimulated cells of monocytic and myeloid differentiation: an alternative initiation of the coagulation protease cascade

Monocytes initiate coagulation through regulated surface expression of tissue factor and local assembly of a proteolytic enzymatic complex formed by tissue factor and factor VII/activated factor VII. We now show that, in the absence of these initiating molecules, monocytes and cell lines of monocytic/myeloid differentiation can alternatively initiate coagulation after exposure to ADP. The molecular basis for this procoagulant response consists of two distinct events. First, cell stimulation with ADP induces high-affinity binding of coagulation factor X to the surface-adhesive receptor Mac-1. Locally, Mac-1-concentrated factor X is then rapidly proteolytically cleaved to an active protease with size and activity characteristics of activated factor X, which supports the cell-associated formation of thrombin and the procoagulant response. We conclude that the monocytic/myeloid adhesive receptor Mac-1 has the unexpected, specifically inducible property to organize a molecular assembly culminating in rapid fibrin formation that is independently regulated from tissue factor and factor VII/activated factor VII.

Cellular and tissue distribution of MRK20 murine monoclonal antibody-defined 85-kDa protein in adriamycin-resistant cancer cell lines

A murine monoclonal antibody (MAb) specific to adriamycin-resistant K-562 (K-562/ADM) cells, MRK20, was found to react strongly with an 85-kDa protein present in K-562/ADM and adriamycin-resistant ovarian cancer (2780AD) cells. This protein was present at only very low levels in parental cells (K-562 and A2780), methotrexate-resistant K-562 cells (K-562/MTX3, K-562/MTX4 and K-562/MTX5) and cisplatin-resistant ovarian cells (KFr). Immunoelectron microscopically, the protein was found to be located on the cell membrane of K-562/ADM and 2780AD cells. Furthermore, the presence of the protein in various cell lines, normal tissues and surgical materials from patients given no anti-cancer agents was examined by immunocytochemistry and flow cytometry. MRK20 reacted with granulocytes, monocytes and endothelial cells in various tissues, but did not react with tissue macrophages. This 85-kDa protein recognized by MRK20 seems to be the second multidrug-resistance gene-encoded product appearing in adriamycin-resistant cancer cells, following the characterization of 170-180-kDa glycoprotein, and may be important for elucidating the multidrug-resistance mechanism relevant to adrimycin and Vinca alkaloids.

Retinoic acid regulates IgG Fc receptor expression in human myelomonocytic leukemia cells and normal peripheral monocytes

The regulation of IgG Fc receptor (Fc gamma R) expression by retinoic acid (RA) in human myelomonocytic cells at different stages of maturation was studied. RA suppressed IgG-coated erythrocyte (EA) rosette formation of myelomonocytic cells blocked at relatively late stages of differentiation such as ML-1, U-937, THP-1-T, normal monocytes, and fresh cells of patients with acute myelomonocytic leukemia. However, RA increased the percentage of EA rosetting promyelocytes of HL-60 and of patients with acute promyelocytic leukemia and a part of myeloblasts isolated from acute myelogenous leukemia patients. Other myeloblasts including KG-1a, KG-1, and fresh cells from patients with acute myelogenous leukemia were not affected. A kinetic study using HL-60 and THP-1-T demonstrated that an increase required at least a 48-h exposure and that the maximum decrease required approximately 6 h. The RA effect on both cell lines was dose-dependent. The number of Fc gamma R of HL-60 and THP-1-T treated with RA became very close, although untreated THP-1 had almost 10 times as many as HL-60. Kd for IgG in both THP-1-T and HL-60, either untreated or treated with RA, remained unchanged. These observations indicate that one of the important roles of RA is regulation of Fc gamma R expression in myeloid cells.

Effect of fibroblast-derived differentiation inducing factor on the differentiation of human monocytoid and myeloid leukemia cell lines

A fibroblast-derived differentiation inducing factor (F-DIF) purified from medium conditioned by a human fibroblast cell line (WI-26VA4) induced differentiation of human monocytic leukemia cell lines (U-937, THP-1) into cells with macrophage characteristics. F-DIF alone induced the differentiation of ML-1 cells only marginally, but it synergistically increased the differentiation when combined with TNF. Interferon-gamma, tumor necrosis factor, GM-CSF, interleukin-1 and interlukin-4 synergistically enhanced the differentiation of U-937 cells when combined with F-DIF.

Extracellular cAMP formation from host cell ATP by Bordetella pertussis adenylate cyclase

The effect of exogenously added adenylate cyclase from Bordetella pertussis (strain 114) has been investigated in Y-1 mouse adrenal tumor, chinese hamster ovary (CHO) and several other cells. A partially purified adenylate cyclase was found not to enter cells but, nevertheless, produced large amounts of cAMP in the medium. We could show that this resulted from release of ATP (and not larger molecules). The ATP released by the cells could be (1) directly measured and was replenished after each change of medium; (2) was reciprocally related to the cAMP produced; and (3) was competed for by ATPases present in added serum or by hexokinase and, less effectively, by exoenzymes on the cell surface. The extent of ATP leakage varied widely between different cell lines, being marked in CHO and Y-1 adrenal cells but negligible in transformed lymphocyte lines. The uncertainty of the origin of cAMP found in media of cultured cells requires separate analysis of cell and medium cAMP and an assessment of ATP leakage.

Effect of probucol on macrophages, leading to regression of xanthomas and atheromatous vascular lesions

To explain the strong effect of probucol on xanthomas, the drug's effect on lipid storage in macrophages in the presence of denatured low-density lipoprotein (LDL) was studied. Two macrophage cell lines, UE-12 and THP-1, were used. Those cells stored lipids and became foam cells when they were incubated with acetylated LDL (acetyl-LDL). When probucol was added into the medium either in ethanolic solution or in the form bound to LDL, the storage of cholesterol and other lipids and the development of macrophages into foam cells were greatly suppressed. Two functions of probucol should be considered: (1) It inhibited the uptake of acetyl-LDL by macrophages; and (2) it enhanced the release of cholesterol from these cells. Cells were first incubated with probucol. After the cells were washed with fresh medium, the radiolabeled acetyl-LDL was added to the medium and the degradation of acetyl-LDL was measured. Increasing the concentration of probucol led to a decrease in degradation of acetyl-LDL by macrophages. Probucol also suppressed the uptake of albumin. Macrophages were incubated with acetyl-LDL, washed once, then incubated with or without probucol and high-density lipoprotein (HDL). Addition of HDL caused a rapid decrease in cholesterol content in the cells, and this phenomenon was enhanced by probucol for both kinds of cells. The secretion of apolipoprotein E was also stimulated by the addition of probucol. These 2 sets of experimental results suggest that probucol prevents lipid storage in macrophages by both suppressing the uptake and stimulating the release of cholesterol and other lipids into or from the macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of phagocyte cytochrome b heavy chain gene expression by interferon gamma

Phagocytic cells, such as macrophages and polymorphonuclear leukocytes, produce a "respiratory burst" in which oxygen is reduced to superoxide and other active oxygen species responsible for many of the microbicidal, tumoricidal, and inflammatory activities of these cells. Interferon gamma has been shown to augment phagocyte superoxide production, but the molecular mechanisms underlying this effect have remained unknown. Recently a key component of the oxidase, phagocyte cytochrome b, has been characterized as a heterodimer of a 91-kDa glycoprotein and a 22-kDa polypeptide. The present studies examined the effects of human recombinant interferon gamma on the expression of the genes for these components of the cytochrome b. In vitro treatment with interferon gamma substantially increases the level of phagocyte cytochrome b heavy chain gene transcripts in normal polymorphonuclear leukocytes, normal monocyte-derived macrophages, and the monocytic leukemia cell line THP-1. Light chain gene transcripts are less affected. In monocyte-derived macrophages and THP-1 cells, the enhanced expression of the heavy chain gene appears in large part attributable to increased rates of transcription. Treatment of monocyte-derived macrophages with human recombinant interferon alpha (a down-regulator of the respiratory burst) decreased the heavy chain transcript levels; interferon beta produced no detectable change. These findings demonstrate the responsiveness of one essential component of the phagocyte oxidase system to activation by interferon gamma and provide a rationale for its use to augment phagocytic function in chronic granulomatous disease.

Isolation of cDNAs encoding finger proteins and measurement of the corresponding mRNA levels during myeloid terminal differentiation

The finger motif is a tandemly repeated DNA-binding domain recently identified in the primary structure of several eukaryotic transcriptional regulatory proteins. It was first described for Xenopus TFIIIA, a factor required for transcription of 5S ribosomal genes and subsequently identified in regulatory proteins from other eukaryotic organisms including yeast, Drosophila and mammals. In this paper we report the isolation and characterization of two human cDNA clones both encoding for multifingered protein products. Transcriptional studies indicate that the two finger genes are expressed in a variety of human tissues. Moreover, upon in vitro induced terminal differentiation of human HL-60 and THP-1 myeloid cell lines the expression of both genes is drastically reduced. These data provide support for the existence of a human multigene family coding for regulatory finger proteins which are likely involved in the processes of cell differentiation and/or proliferation.

Molecular cloning of a human immunoglobulin G Fc receptor

Human IgG Fc receptor (Fc gamma R) cDNA clones were isolated by cross-species hybridization by probing cDNA libraries with the low-affinity Fc gamma R beta 1 cDNA clone from mouse as well as a pool of oligonucleotides constructed from the nucleotide sequence of this Fc gamma R. Three cDNA clones were isolated and analysis of the predicted amino acid sequence indicated that the human Fc gamma R protein is synthesized with a 34-amino acid leader and the mature protein is composed of 281 amino acids. The extracellular region of this Fc gamma R was divided into two domains, which were very similar to each other and to the corresponding regions of both mouse alpha and beta Fc gamma Rs and showed a clear relationship to immunoglobulin variable regions. One possible N-linked glycosylation site was found in each of the extracellular domains. The human Fc gamma R leader sequence was shown to be similar to the mouse alpha Fc gamma R leader sequence, but the transmembrane region was most similar to the mouse beta 1 Fc gamma R. The intracellular domain of the human Fc gamma R was surprisingly different from both mouse Fc gamma Rs. RNA blot analysis of human cells demonstrated two transcripts (2.5 and 1.5 kilobases) that arise by use of different adenylylation signals. The cellular expression of these transcripts suggest that they encode the low-affinity p40 Fc gamma R protein.

Erythroid differentiation factor is encoded by the same mRNA as that of the inhibin beta A chain

We have isolated a protein that exhibits a potent differentiation-inducing activity toward mouse Friend erythroleukemia (MEL) cells and human K-562 cells. The protein, designated erythroid differentiation factor (EDF), was found in the culture fluid of human THP-1 cells that had been treated with phorbol 12-myristate 13-acetate. EDF is a homodimer with a Mr of 25,000; the Mr of the monomer is 15,500. cDNA clones encoding the Mr 15,500 subunit of EDF from THP-1 libraries were isolated and sequenced. Surprisingly, the sequence of EDF mRNA is identical to that for the beta A subunit of inhibin, a gonadal protein that suppresses the secretion of pituitary follicle-stimulating hormone. Southern blot analysis indicates that only one gene for EDF/inhibin beta A exists in the human genome. When the EDF subunit cDNA was linked to a simian virus 40 expression vector containing the dihydrofolate reductase gene and transfected into Chinese hamster ovary dihydrofolate reductase negative cells, the transformants began to secrete EDF, demonstrating that the cDNA actually encoded the EDF subunit.

Establishment of a human cell line (Mono Mac 6) with characteristics of mature monocytes

A monocytic cell line, termed Mono Mac, was established from peripheral blood of a patient with monoblastic leukemia. Two clones, designated Mono Mac I and Mono Mac 6, were isolated and both were assigned to the monocyte lineage on the basis of morphological, cytochemical and immunological criteria. Most importantly, the clones express NaF-sensitive non-specific-esterase, produce reactive oxygen and stain with MAb My4. Mono Mac 6, in addition, constitutively exhibits phagocytosis of antibody-coated erythrocytes in 80% of the cells and reacts with a panel of MAbs that are specific for mature monocytes, i.e., M42, LeuM3, 63D3, Mo2 and UCHMI. By contrast, the monoblastic cell lines U937 and THP-I are negative for all these markers. Only expression of My4 could be detected after differentiation induced by interferon-gamma (IFN-gamma). Similar treatment of Mono Mac I, however, resulted in staining with all the monocyte-specific MAbs mentioned above, while IFN-gamma treatment of Mono Mac 6 enhanced antigen expression. In addition, the cells showed an increased frequency of multinucleated cells with a rise from 4.8% to 21.9%. Mono Mac 6 appears to be the only one of the cell lines studied to constitutively express phenotypic and functional features of mature monocytes.

Expression of erythroid differentiation factor (EDF) in Chinese hamster ovary cells

Plasmid DNA containing EDF subunit cDNA and mouse dihydrofolate reductase (DHFR) cDNA was transfected into CHO DHFR- cells by the calcium-phosphate method. DHFR positive transformants secreted recombinant EDF (r-EDF) constitutively in an active form and accumulated it in the conditioned medium. Furthermore, cells which were resistant to methotrexate (MTX : 0.5 microM) secreted r-EDF up to 1 microgram/ml. r-EDF was identical to natural EDF (n-EDF) produced by human acute monocytic leukemia cell line, THP-1, as regards its dimeric structure and a biological activity.

Cell cycle-related expression of surface antigens on myelomonocytic leukemia cells

We investigated the relationship between the expression of surface antigens and the cell cycle phase in leukemic cells from cell lines and one patient using two-color flow cytometry, in order to determine the reason for the uneven expression of some markers which frequently leads to equivocal results as to leukemic phenotyping. As a result, it was demonstrated that monocyte-related differentiation markers, including I2, My4, Mo1 and Mo2, on monocytoid leukemic cells are preferentially expressed at the G0/G1 phase. Consequently, it is expected that the positivities for such markers vary with the proliferation status of the leukemic cells.

RAS gene mutations in acute and chronic myelocytic leukemias, chronic myeloproliferative disorders, and myelodysplastic syndromes

We report on investigations aimed at detecting mutated RAS genes in a variety of preleukemic disorders and leukemias of myeloid origin. DNA transfection analyses (tumorigenicity assay) and hybridization to mutation-specific oligonucleotide probes established NRAS mutations in codon 12 or 61 of 4/9 acute myelocytic leukemias (AML) and three AML lines. Leukemic cells of another AML patient showed HRAS gene activation. By using a rapid and sensitive dot-blot screening procedure based on the combination of in vitro amplification of RAS-specific sequences and oligonucleotide hybridization we additionally screened 15 myelodysplastic syndromes, 26 Philadelphia chromosome-positive chronic myelocytic leukemias in chronic or acute phase, and 19 other chronic myeloproliferative disorders. A mutation within NRAS codon 12 could thus be demonstrated in a patient with idiopathic myelofibrosis and in another with chronic myelomonocytic leukemia. Moreover, mutated NRAS sequences were detected in lymphocytes, in granulocytes, as well as in monocytes/macrophages of the latter case.

Effects of polyunsaturated fatty acids and of their oxidation products on cell survival

The stimulatory, cytostatic and cytotoxic effects of polyunsaturated fatty acids, prostaglandins, thromboxanes, hydroperoxy fatty acids, hydroxy fatty acids and leukotrienes on normal and tumor cells are described. Their effects are related to the ability of the cells to undergo lipid peroxidation. The significance of controlled peroxidation of selected polyunsaturated fatty acids in the control of tumor development is examined. It is suggested that selected polyunsaturated fatty acids if used at appropriate concentrations may have a protective role against cancer development by inducing and/or mediating cytotoxic reactions in malignant cells directly or indirectly through the intermediacy of immune cells.

Induction of acetylated low density lipoprotein receptor and suppression of low density lipoprotein receptor on the cells of human monocytic leukemia cell line (THP-1 cell)

THP-1 cells, a human cell line established from acute monocytic leukemia cells, degraded native human low density lipoprotein (LDL) through a LDL-specific pathway, but had no ability to degrade acetylated LDL. When the cells were treated with 12-o-tetradecanoyl-phorbol-13-acetate (TPA) to differentiate into the macrophage-like stage, those acquired the ability to degrade acetylated LDL through its specific pathway and lost the ability to degrade native LDL. Degradation of acetylated LDL by the differentiated cells was not reduced by preincubation with either acetylated LDL or native LDL.

Purification and characterization of erythroid differentiation factor (EDF) isolated from human leukemia cell line THP-1

We isolated a protein, from a cell line of human origin, which exhibits extensive differentiation inducing activity toward Friend leukemia cells. The protein, called Erythroid Differentiation Factor (EDF), was found in a 4 day culture of THP-1 cells performed in the presence of 4 beta-phorbol 12-myristate 13-acetate(PMA). EDF is a homodimer of a molecular weight of 25,000, with an NH2-terminal sequence identical to that of the beta A-chain of porcine Inhibin. It was suggested that a single protein species is responsible for the activities of both EDF and FRP, a FSH releasing protein isolated from porcine ovarian follicular fluid.

Ph1-positive CML-derived myeloid-monocytoid precursor cell line producing substance(s) that stimulates normal CFU-C

A new Ph1-chromosome positive cell line, KOPM-28. was established from a patient with chronic myelogenous leukemia (CML) in blast crisis. KOPM-28 cells were phenotypically immature: without azurophilic granules; negative for myeloperoxidase and positive for specific and nonspecific esterases. The nonspecific esterase reaction was intensified by TPA, and retinoic acid reinforced the specific esterase reaction without inducing morphological changes. KOPM-28 cells were not phagocytic. The cells expressed complement receptors, myeloid-monocytoid antigens, an Ia-like antigen and T4 antigen. CALLA, T-lymphocyte specific antigens, B-lymphocyte related antigen and platelet-megakaryocyte-megakaryoblast specific antigen were not detected. KOPM-28 cells formed colonies in semi-solid medium; this ability was augmented by GM-CSA. The addition of culture medium conditioned by KOPM-28 cells to normal bone marrow cells resulted in the increase of the CFU-C colonies. These findings indicate that KOPM-28 cells have features of myeloid and monocytoid precursor cells and that they are producing substance(s) which stimulates normal CFU-C.

Isoenzyme studies in human leukemia-lymphoma cell lines--V. Induction of differentiation by T-cell derived differentiation-inducing activity

A panel of human leukemia cell lines from various lineages (T-cell, pre B- and Non-T/Non-B cell, myelomonocytic and erythroleukemia cell lines) were utilised as model systems of the distant effects of differentiation-inducing activity (DIA) produced by the T-leukemia cell line HUT-102. DIA inhibited cell proliferation and induced distinct morphological changes which were more pronounced in the myelomonocytic and erythroleukemia cell lines than in the lymphoid cell lines. DIA triggered in the myelomonocytic and erythroleukemia cell lines an increase in the number of NBT-reducing cells and caused strong adherence to plastic surface. The T-cell lines showed aggregation of cells in floating clusters. In the isoenzyme analysis of the enzymes carboxylic esterase and acid phosphatase, it was found that DIA stimulated the new expression of isoenzymes and a stronger staining intensity of several isoenzyme bands in all cell lines, however, at varying degrees. HL-60 and HEL displayed newly a monocyte-specific isoenzyme. Several myelomonocytic and erythroleukemia cell lines were triggered to express the tartrate-resistant acid phosphatase isoenzyme. The cell kinetic, morphological, functional and isoenzymatic data demonstrated that DIA effected the development of the different blood cell types. However, it appears that the cells reached a new differentiation block after acquired expression of differentiation-linked features; the lymphoid cell lines were more limited in their response to DIA than the myeloid and erythroid cells.

Interleukin 1 inhibitory activity secreted by a human myelomonocytic cell line (M20)

Culture supernatants from a myelomonocytic cell line (M20) were found to inhibit interleukin 1 (IL 1) activity in vitro. The factor, isolated from these supernatants, inhibited augmentation of phytohemagglutinin response of mouse thymus cells induced by IL 1 derived from several established cell lines. Various IL 1-dependent activities such as lymphocyte and fibroblast proliferation in vitro were also inhibited by the factor. The factor did not inhibit IL 2-induced or other proliferative responses not related to IL 1. Preliminary biochemical characterization of the factor indicated that the activity resides in a protein with a molecular mass of 52 kDa.

Identity of differentiation inducing factor and tumour necrosis factor

Human myelogenous leukaemic cells can be induced to differentiate into the monocyte/macrophage pathway by protein inducers called differentiation inducing factors (DIF) in conditioned media of mitogen-stimulated human peripheral blood leukocytes. However, human DIF has not yet been well characterized. DIF is known to be a T-cell lymphokine, as it can be obtained from the T-cell line HUT-102 and can be partially purified from medium conditioned by phytohaemagglutinin (PHA)-stimulated lymphocytes. We found that monocytes also produce factor(s) that induce differentiation of human myelogenous leukaemia cell lines to cells with macrophage-like characteristics. This factor(s) has activity different from that of colony-stimulating factor(s) or interferons. We have now purified a DIF to homogeneity from medium conditioned by PHA-stimulated leukocytes using a human myeloblastic leukemia cell line, ML-1, as target cells. The purified DIF has a relative molecular mass (Mr) of approximately 17,000, with an NH2-terminal sequence the same as that of human tumour necrosis factor (TNF). Recombinant human TNF (rHuTNF) induces differentiation of ML-1 cells and an anti-pDIF monoclonal antibody can neutralize both differentiation inducing activity and cytotoxic activity of DIF and rHuTNF. The findings indicate that one of the DIF(s) produced by leukocytes is probably TNF.

Vitamin D compounds. Effect on clonal proliferation and differentiation of human myeloid cells

We examined the effect of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) and a variety of vitamin D analogs on proliferation and differentiation of normal and leukemic myeloid clonogenic cells. Only cells from myeloid leukemic lines that contained relatively mature cells (HL-60, U937, THP, HEL, M1) were induced to differentiate and were inhibited in their clonal growth by exposure to 1 alpha,25(OH)2D3 (50% inhibition, 3 X 10(-8)-8 X 10(-10) M). A fluorinated analog of vitamin D was 5-10-fold more potent than 1 alpha,25(OH)2D3. Cells from a human myeloblast line (KG-1) and normal human granulocyte-monocyte stem cells (GM-CFC), both of which depend on colony-stimulating factor (CSF) for clonal growth, were stimulated in their clonal proliferation by 1 alpha,25(OH)2D3 in the presence of suboptimal concentrations of CSF. Leukemic cells from 10 of 14 patients with myeloid leukemia, but not normal GM-CFC from 12 patients in remission, were markedly inhibited in their clonal proliferation by 1 alpha,25(OH)2D3. Our results suggest that 1 alpha,25(OH)2D3 may be a cofactor in hematopoiesis and that vitamin D analogs may have a differential effect on normal versus leukemic growth.

In vitro differentiation and establishment of cell lines derived from human myelomonocytic leukemia cells

Primary cultures of cells derived from 13 patients with acute myelomonocytic leukemia (AMML) were studied with particular emphasis on in vitro proliferation, cell differentiation and the mode for establishment of cell lines. Using irradiated human macrophage monolayers to assist cell growth, we obtained four new cell lines of myelomonocytic origin. All the cell lines were characterized for cytochemical markers and response to phorbol esters (TPA), a differentiation inducing agent. In the absence of any inducing agent, spontaneous differentiation of blast cells into mature macrophages-like cells occurred in 8 out of the 13 primary cultures. Thus, maturation induction by agents such as TPA is not always required in order to obtain leukemic cell differentiation in vitro. The regulation of cell proliferation and differentiation by cellular interactions and by extrinsic soluble products is discussed in detail, in the light of these findings.

Generation of a monoclonal anti-GP70 antibody and characterization of its reactivity with various human cell lines and cells from leukemia-lymphoma patients

Monoclonal anti GP-70 antibodies (BI) were generated in mice and used for screening of various malignant and non-malignant cell lines. The reactivity of these monoclonal antibodies was compared with that obtained with the polyclonal anti GP-70 antibody described in earlier studies [1-3]. The results indicated complete similarity in reactivity of both of the antibodies used. Furthermore, the reactivity of BI antibodies with cell samples obtained from a variety of leukemia and lymphoma patients and with peripheral blood samples from healthy blood donors was also very similar to the pattern of specificity described in earlier reports for the polyclonal preparation. From these studies we conclude that the monoclonal antibodies can substitute the polyclonal anti GP-70 antibodies in the diagnosis and subtyping of B-type leukemias and lymphomas.

In-vitro effects of antineoplastic prostaglandins on human leukemic cell growth and normal myelopoiesis

The effects of prostaglandin (PG)E1, PGD2 and 9-deoxy-delta 9-PGD2 (PGJ2) on the clonogenic growth of six kinds of human leukemic cell lines (K562, KG1, HL60, U937, THP1 and Molt4) and normal human myeloid progenitor cells (CFU-GM) were studied using semisolid agar cultures. While the degree of suppression of leukemic growth by PGE1 varied from cell line to cell line, PGD2 and PGJ2 equally suppressed the growth of all leukemic cell lines. The potency of growth inhibition was as follows: PGJ2 greater than PGD2 greater than PGE1. The increase of cellular cAMP level induced by prostaglandin treatment did not parallel their cytotoxic potency. Normal myeloid colony formation was also suppressed by PGE1, PGD2 or PGJ2. In contrast to the preferential inhibition of macrophage colony formation by PGE1, such lineage-selective suppression was not observed for PGD2 or PGJ2. These findings suggest that PGD2 and PGJ2 potently inhibit the leukemic growth by a different mechanism from that of PGE1 and by a cAMP-independent mechanism. These prostaglandins seem to be promising chemotherapeutic agents for acute leukemia.