Lysozyme synthesis by established human and murine histiocytic lymphoma cell lines

Role of phorbol diesters in in vitro murine megakaryocyte colony formation

In vitro megakaryocyte differentiation is regulated by two activities: a megakaryocyte colony-stimulating activity (Mk-CSA), which is required for proliferation, and an auxiliary factor, megakaryocyte potentiating activity, which plays a role in later differentiation events. Tumor-promoting phorbol esters alter many cellular differentiation-related events. Thus, it was hypothesized that phorbol esters may bring about megakaryocyte differentiation in vitro. 4 beta-Phorbol 12-myristate 13-acetate (PMA), when co-cultured with a source of Mk-CSA, stimulated a threefold increase in colony numbers. Co-culture of PMA and megakaryocyte potentiator activity did not stimulate colony formation, thus eliminating any action of PMA as an Mk-CSA. The direct effect of PMA on the formation of megakaryocyte colonies was established by (a) the function of PMA as a megakaryocyte potentiator in serum-free experiments, (b) the ability of PMA to stimulate megakaryocyte colony formation using bone marrow cells depleted of populations known to produce potentiating activity, (c) the inability of bone marrow adherent cells previously treated with phorbol, 12,13-dibutyrate (PDBu) to augment megakaryocyte colony formation, and (d) the ability of PMA to induce the growth of immature megakaryocytes into large single megakaryocytes. Structure:activity experiments resulted in equivalent activities for PMA and PDBu, whereas the nontumor promoter phorbol 12,13-diacetate and phorbol itself lacked activity. The observations in this study indicate that phorbol esters can bring about megakaryocyte differentiation, and during colony formation, can induce effects identical to those brought about by biological sources of megakaryocyte potentiator activity.

Effect of retinoic acid on the proliferation and phagocytic capability of murine macrophage-like cell lines

Retinoic acid (RA) exerted a variable degree of growth inhibitory activity on the macrophage-like cell lines P388D1, J774.2, WEHI-265, WEHI-3, and PU-5. Comparison of cell proliferation and clonal growth suggests that at concentrations of 10(-9)-10(-6) M the inhibitory activity stems from processes leading to elongation of cell cycle time and not from terminal differentiation processes. RA was shown to be a potent inducer of the development of high-phagocytic phenotypes (assessed by phagocytosis of heat-killed yeast cells) in the P388D1, J774.2, and WEHI-265 cell lines which differ substantially in their proliferative and adherence characteristics. The PU-5 and WEHI-3 cell lines were not induced by RA to express an enhanced phagocytic activity toward heat-killed yeast cells. The augmented phagocytic capability was dose dependent over a wide range of RA concentrations. In P388D1 cells, 2 X 10(-12) M RA already exerted significant phagocytosis augmentation effects, which progressively increased up to 2 X 10(-5) M RA, the highest concentration tested. Retinal, retinyl acetate, and retinol had similar effects to those of RA on both cell adherence and phagocytosis in P388D1 cells, albeit at concentrations four to six orders of magnitude higher. Optimal development of the high-phagocytic phenotype in P388D1, J774.2, and WEHI-265 cells required at least 96 hr of culture in the presence of RA; at 48 hr and 23 hr the effects were already substantial, whereas at 4 hr of exposure to RA no significant enhancement of phagocytosis could be detected. Thus both extended periods of culture in the presence of RA (more than two to three cell cycles) and high concentrations were needed for induction, in more than 90% of the cells, of the expression of a high-phagocytic phenotype. The reversion to a low-phagocytic phenotype upon removal of RA was also rather slow and required several cell cycles. In P388D1 cells RA also enhanced the phagocytosis of latex beads but had no effect on the phagocytosis of starch particles, or the extent of binding of immunoglobulin G-coated sheep red blood cells (SRBC). The expression of receptors for concanavalin A and for nonopsonized SRBC remarkably increased in RA-treated cells, as was the ability to perform Fc-receptor mediated erythrophagocytosis. Both P388D1 cells and WEHI-265 cells were induced by RA to express nitroblue tetrazolium reducing activity. The data suggest that RA induces profound changes in the functional capabilities of macrophage-like cell lines which are apparently not dependent on cessation of growth and terminal differentiation processes.

H-2-linked low-molecular weight polypeptide antigens assemble into an unusual macromolecular complex

The major histocompatibility complex (MHC) is a cluster of tightly linked genes whose products are of central importance in the functioning of the immune system. Class I and II MHC antigens are integral membrane proteins which regulate cell-surface interactions between T cells and their targets, while class III antigens are components of the complement system of serum proteins. All available evidence indicates that the structure and function of the MHC and its gene products are highly conserved among species (for review, see ref.5). We recently reported the existence in murine cells of a fourth class of MHC-linked polypeptides which are biochemically and genetically distinct from previously identified MHC gene products: BALB.B anti-BALB/c (anti-H-2d) antiserum immunoprecipitates a set of 16 cytoplasmic low-molecular weight polypeptides (LMP) from BALB/c spleen cells and from the WEHI-3 cell line. The production of these peptides is coordinately regulated (by immune interferon) with the production of the class I and II MHC antigens, suggesting that they too are functionally relevant to the immune system. We demonstrate here that these 16 polypeptides are associated with one another in vivo as a very large (580,000-molecular weight, Mr) noncovalent complex. The unusual nature of this complex has allowed the non-immunochemical identification of similar complexes from (serologically negative) H-2b murine cells and from a human cell line. Thus, LMP antigens display two properties in common with other MHC antigens: they are both polymorphic and genetically conserved across species.

1 alpha,25-dihydroxyvitamin D3 induces maturation of the human monocyte cell line U937, and, in association with a factor from human T lymphocytes, augments production of the monokine, mononuclear cell factor

The monocyte factor, interleukin 1, or other factors homologous with interleukin 1, modulates functions of a variety of cells, including T and B lymphocytes, synovial cells, and chondrocytes. We have reported that a human monocyte cell line, U937, produces interleukin 1 when incubated with a soluble factor from lectin-stimulated T lymphocytes. We have also shown that U937 cells have a specific cytosolic receptor for 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25[OH]2D3). We now report that 1 alpha,25(OH)2D3(10(-11)-10(-10) M) induces maturational changes in the U937 cells similar to those produced by conditioned medium from lectin-stimulated T lymphocytes (increase in Fc receptors and OKM1 binding and decrease in proliferation), but does not induce monokine production as measured by mononuclear cell factor activity. 1 alpha,25(OH)2D3 is 200-300-fold more effective than 25-hydroxyvitamin D3, which is consistent with the known biological potency of these vitamin D3 metabolites. 1 alpha,25(OH)2D3 and the lymphokine together markedly augment maturational effects and, in addition, augment monokine production. The specificity of the interaction is further demonstrated by the lack of augmentation of monokine production with 1 beta,25-dihydroxyvitamin D3 in the presence of lymphokine. These interactions of a classical hormone and the hormonelike product(s) of the immune system with U937 cells serve as a model for human monocyte/macrophage differentiation and suggest a role for these interactions in some aspects of inflammation.

Mouse yolk sac and intraembryonic tissues produce factors able to elicit differentiation of erythroid burst-forming units and colony-forming units, respectively

This work was aimed at elucidating the environmental conditions that account for the production of embryonic erythrocytes in the mouse yolk sac (YS), while the adult-type hemoglobin and erythrocytes are generated in the fetal liver. Differentiation of YS hemopoietic stem cells (YS-HSC) of 9.5-day mouse embryos (prior to the colonization of the liver rudiment by HSC) was investigated in vitro. The influence of well-characterized erythroid growth factors, burst-promoting activity (BPA) and erythropoietin (EPO), which trigger the differentiation of early erythroid burst-forming units (BFU-E) and late erythroid colony-forming units (CFU-E), respectively, was tested on the YS-HSC in two different systems of culture: (i) organ culture and (ii) clonal culture in methylcellulose. When studied in organ culture, where the YS microenvironment was maintained, YS-HSC required only additional EPO to attain complete maturation into adult erythrocytes within 7 days. In contrast, YS hemopoietic single cells grown in methylcellulose, and thus released from the influence of the YS, required the presence of both BPA and EPO to generate BFU-E-derived colonies synthesizing high concentrations of hemoglobin. It is concluded that 9.5-day YS from mouse embryos is by itself able to promote the first differentiation steps of the adult lineage YS-HSC due to an intrinsic production of a BPA-like activity. In contrast, these experiments demonstrate that EPO or an EPO-like activity is not produced by YS tissues. As demonstrated earlier, if embryonic tissue is added to YS organ culture, although separated from it by a filter preventing cell contact, YS-HSC differentiate into adult erythrocytes producing adult-type hemoglobins. This shows that, in contrast to YS tissues, the early embryo produces EPO or a factor that can substitute for EPO.

Effect of an anti-murine transferrin receptor-ricin A conjugate on bone marrow stem and progenitor cells treated in vitro

A monoclonal antibody with specificity for murine transferrin receptor was conjugated with the toxic A subunit of ricin. The dose range, specificity, and kinetics of inhibition of protein synthesis of the conjugate were determined on the murine T-lymphoma cell line, BW5147. When toxin was present throughout the period of culture, in vitro myeloid (CFUc) and erythroid (CFUe and BFUe) bone marrow colonies were inhibited by doses of conjugate comparable to those that inhibit protein synthesis in murine cell lines (IC50 of 5 X 10(-11)M). Bone marrow exposed briefly (30 min to 6 h) to anti-transferrin receptor antibody-ricin A conjugate was assayed for myeloid (CFUc) and erythroid (CFUe and BFUe) progenitors in vitro and for in vivo spleen colony formation (CFUs). Only CFUe were depleted by this pulse exposure, consistent with the higher frequency of proliferating cells and transferrin receptor expression in the CFUe population relative to other progenitors.

Biologic properties of factor-independent nonadherent hematopoietic and adherent preadipocyte cell lines derived from continuous bone marrow culture

Cell lines dependent for growth upon an inducer T-cell synthesized glycoprotein factor interleukin-3 have been derived from continuous mouse bone marrow cultures. These factor-dependent (FD) lines have been shown to be multipotential (erythroid/basophil/neutrophil) or (eosinophil/basophil/neutrophil); or are unipotent basophil or neutrophil granulocyte cell lines. Both classes of cloned FD lines have maintained self-renewal in vitro for several years with absolute growth dependence on freshly added IL-3. In four instances, factor-independent (FI) variant cell lines were derived, one by subculture in medium containing hydrocortisone and 25% horse serum and three by evolution of variants from cloned FD lines. One class of (FI) lines demonstrated adherent fibroblast-like morphology with differentiation to differentiated adipocytes in medium containing 10(-5) hydrocortisone. A second class of cell lines evolved from cloned FD lines and each grew in suspension culture to a saturation density over 10-fold greater than that for the parent FD line (greater than 10(7)/ml) and each contained no detectable hematopoietic cellular differentiation markers by histochemistry or cell surface receptors. In contrast to IL-3 dependent cell lines, (FI) cell lines failed to differentiate to mature granulocyte morphology in diffusion chambers in vivo. The FI cell lines formed no detectable CFUs in vivo, did not reconstitute hematopoiesis in irradiated mice and did not form tumors in vivo. The failure of the (FI) lines to form tumors and lack of detectable hematopoietic differentiation capacity indicates that these lines may represent an intermediate state between normally regulated hematopoietic cellular self-renewal and malignant transformation.

Expression of transferrin receptor on murine hematopoietic progenitors

We have used a monoclonal antibody against the murine transferrin receptor to study the expression of the transferrin receptor on the hematopoietic progenitor cells (BFU-E, CFU-E, and CFU-C) present in mouse bone marrow. Elutriation and cell-sorting data are consistent with the hypothesis that most CFU-E are transferrin receptor positive while most BFU-E express much less transferrin receptor. CFU-C comprise both transferrin-receptor-positive and -negative cells.

Binding of 125I-insulin to the human histiocytic lymphoma cell line U-937: effect of differentiation with retinoic acid

The human histiocytic lymphoma line U-937 consists of cells having characters of immature monocytes. We have demonstrated that these cells possess highly specific insulin receptors with binding properties similar to that found for mature human blood monocytes. 125I-insulin binding increased progressively with time to reach a maximum at 90 min at 22 degrees C and was proportional to the number of cells in the incubation medium. Insulin degradation as assessed by TCA precipitation was negligible. Scatchard analysis of the binding data was curvilinear and the total number of insulin binding sites was around 13,500. The average affinity profile gave an 'unoccupied site' affinity constant of 1.34 nM-1. When the U-937 cells were induced to differentiate into morphologically and functionally monocyte-like cells, after incubation with retinoic acid, the total number of binding sites decreased significantly with no change in the affinity of the hormone for its receptor.

A requirement for cholesterol and its structural features for a human macrophage-like cell line

The lipid requirements of a human macrophagelike cell line were studied. The cells grew only about one generation in a medium supplemented with delipidated serum; during the growth the cholesterol content of the cells was depleted. Growth was restored by including in the medium serum lipids subjected to alkaline hydrolysis or cholesterol. The extent of growth was dependent on cholesterol concentration. No growth was obtained with 5-cholestene, 5-cholesten-3-one, cholesteryl chloride, coprostanol, beta-sitosterol, or stigmasterol. Very limited growth occurred with cholesterol methylether, epicholesterol, or beta-cholestanol. Therefore, for optimal growth of these cells there is a stringent requirement for the structural features of cholesterol, which include a 3-beta OH group, a delta 5-double bond, a trans ring A/B configuration, and freedom of the side chain from bulky groups. This stringency far exceeds what was previously reported for other cells. Of the six sterols that failed to support growth at all, five were incorporated into cells moderately to extensively. This suggests that assembly of a functional membrane is impaired when these sterols are used as substrates for growth.

Phenotypic and cytogenetic characteristics of a new Epstein-Barr virus negative cell line (SKW 4) derived from a B-cell lymphoma

A new Epstein-Barr virus nuclear antigen (EBNA) negative cell line SKW 4 has been established in vitro from a patient with diffuse histiocytic lymphoma. The SKW 4 seems to be an authentic human tumour cell line as evidenced by its EBV negativity, monoclonality and aneuploidy tested during early in vitro passage. The cell line expresses surface mu and kappa-chains, HLA-DR antigen, C3 and Fc receptors and B-cell lineage antigens. The karyotypic analyses demonstrated many numerical and structural aberrations. No Burkitt lymphoma associated translocations (t8;14, t2;8, t;22) were detected, but most of the markers found are those commonly associated with various types of human cancer. The SKW 4 thus represents the most common type of 'histiocytic lymphoma', that with a B-lymphoid cell phenotype, but is unique among HL derived lymphoma lines in its strong expression of a Helix pomatia A agglutinin binding surface glycoprotein of an apparent molecular weight of 75 000 daltons.

Malignant myeloblastic transformation of murine long-term bone marrow cultures by F-MuLV: in vitro reproduction of a long-term leukemogenesis, and investigation of preleukemic events

A Friend helper virus I-5(F-MuLV) which induces myeloblastic leukemias in mice after a latency of several months, was used to infect long-term bone marrow cultures. From 48 to 71 weeks after in vitro infection, 4/14 cultures gave rise to transplantable malignant myeloblastic cells. These cells were shown to genuinely result from as in vitro transformation of virus-infected normal bone marrow cells. The in vitro transformation reproduced the course of the in vivo disease. It provided unique material for in vitro investigation of the preleukemic stages of long-term leukemogenesis. Successive cellular events were: (1) freezing of the normal myelomonocytic differentiation process; (2) change from factor-dependent to an autonomous growth; (3) acquisition of in vivo tumorigenicity.

Wheat-germ agglutinin initiates monocytoid cell killing of non-antibody-coated erythrocytes

Cells bearing alien surface antigens can be specifically destroyed by antibodies directed to the antigens and certain Fc receptor-bearing lymphoid or monocytoid cells through a killing mechanism known as antibody-dependent cellular cytotoxicity (ADCC). The present study was undertaken to see if lectins could substitute for specific antibody in ADCC and initiate lysis of non-antibody-coated erythrocytes. Human peripheral blood leucocytes and mouse PU-5 monocytoid cell lines were used as effector cells. Target-cell destruction was measured by the specific release of 51Cr. Our data indicated that Wheat-germ agglutinin (WGA), but not concanavalin A or soybean agglutinin, could activate killing of non-antibody-coated erythrocytes by human peripheral blood leucocytes and PU-5 cells. The membrane structure on the effector cell that was triggered by WGA directly related to N-acetyl-glucosamine and may be adjacent to, if not part of, the Fc receptor.

Embryonic lethal mutation in mice induced by retrovirus insertion into the alpha 1(I) collagen gene

Experimental insertion of a retrovirus into the germ line of mice has resulted in an embryonic recessive lethal mutation. Integration of the proviral genome occurred at the 5' end of the alpha 1(I) collagen gene, leading to complete transcriptional block. Developmental arrest of embryos homozygous at the mutated allele coincides with high expression of the gene in normal embryogenesis. Insertion mutagenesis by retroviruses may offer a general approach to the identification and isolation of genes which are transcriptionally active during mammalian development.

Effect of haematopoietic cell growth factor on intracellular ATP levels

Growth and development of haematopoietic cells in vitro require the presence of specific regulatory molecules. Some of these molecular species appear to have a broad specificity, being able to promote the proliferation and differentiation of multipotential cells, as well as megakaryocytic, erythroid and granulocytic-progenitor cells. Such factors are present in medium conditioned by the growth of lectin-stimulated mouse spleen cells or WEHI-3 myelomonocytic leukaemia cells (WEHI-CM). Using WEHI-CM, we and other have been able to obtain permanently growing, non-leukaemic cell lines of a granulocytic or mast cell nature. Significantly, we have found that the factor in WEHI-CM necessary for the growth of these cells has co-purified with the multi-lineage stimulating activity present in WEHI-CM, suggesting that one molecule may be concerned in the development of multiple cell types. We have now used these cells to investigate the mode of action of this haematopoietic cell growth factor and have found that the requirement of this factor for survival and growth may lie in its ability to modulate ATP levels within the cells.

Immunoregulatory factors from a human macrophage-like cell line. II. A human T-cell lymphokine-induced suppressor factor for lymphocyte proliferation

It has been demonstrated that the human histiocytic lymphoma-derived cell line U937, which has monocytoid characteristics, responds to a concanavalin A-induced T-cell-derived suppressor supernatant (T-SFS) with the release of a factor markedly suppressing mitogen-stimulated proliferation of normal peripheral blood lymphocytes. The suppressor material is not dialyzable, appears within 2 hr of exposure of U937 cells to the T-SFS, persists for at least 24 hr, and has a Mr of approximately 40,000 by gel chromatography. The suppressor factor does not affect the proliferation of continuous T- and B-lymphoid cell lines, distinguishing it from the inhibitor of DNA synthesis also released by U937, but appears to be specific for a stage of activation of normal lymphocytes that is independent of (a) utilization of interleukin-2 and (b) inhibition of production of interleukin-2.

Selective inhibition by monosaccharides of tumor cell cytotoxicity mediated by mouse macrophages, macrophage-like cell lines, and natural killer cells

A series of monosaccharides were tested for their ability to inhibit the effector phase of macrophage-mediated cytolysis against two susceptible murine tumor target cells, L5178Y and RL male I. Two monosaccharides, D-mannose and N-acetyl-D-galactosamine, were found to decrease cytotoxicity consistently in a dose-dependent manner. However, D-mannose preferentially inhibited lysis of RL male I target cells with little effect on lysis of L5178Y target cells, while the reverse was found with N-acetyl-D-galactosamine. Neither monosaccharide interfered with the activation of macrophages by polyinosinic:polycytidylic acid. Natural killer cell activity was decreased by a 25 mM concentration of D-mannose but not by N-acetyl-D-galactosamine, although increasing concentrations of N-acetyl-D-galactosamine were inhibitory. Neither monosaccharide affected cytotoxicity by alloimmune T cells. Cytotoxicity of macrophage-like cell lines against tumor target cells was also decreased by monosaccharides but the pattern of inhibition was different from that seen with activated macrophage effector cells. Both D-mannose and N-acetyl-D-galactosamine inhibited glucose oxidation by activated macrophages but only D-mannose significantly decreased protein synthesis of activated macrophages. These results indicate that monosaccharides can inhibit macrophage-mediated cytotoxicity in a selective manner with the pattern dependent on the tumor target cell used in the assay.

Autocrine function of murine F-MuLV induced myeloblastic cell lines

Four in vitro permanent suspension cell lines have been established from tumoral organs of myelogenous leukemias developed in mice infected with two biologically cloned Friend helper viruses. Leukemic cells in culture were 100% typical myeloblasts exhibiting a strong myeloperoxidase positivity. A few cells were induced to granulocytic or macrophagic terminal differentiation by post-endotoxin serum and by various chemical differentiation inducers such as DMSO, N-butyrate and TPA. We investigated the conditions sustaining the clonal proliferation of these leukemic cells in semi-solid cultures. Cloning efficiencies were increased by the vicinity of a large number of autologous cells and by the addition of autologous culture supernatant, indicating that the leukemic cells were able to stimulate their own in vitro growth. Cloning efficiencies were also increased by different sources of CSA, such as WEHI-3B conditioned medium and post-endotoxin serum. Moreover, the various cell lines stimulated each other through soluble factor(s) secreted in their culture supernatants. Proteins contained in these four culture supernatants were fractionated by successive ammonium sulfate precipitations and ion exchange chromatography. In the four cases the autostimulating activities were eluted in the same fractions as proteins stimulating the normal bone marrow cells colony formation (CSA). These data suggest that the myeloblastic leukemic cell autostimulating factor(s) might be related to the physiological CSA.

Monocytic origin of the human hematopoietic cell line U-937 and its convertibility to macrophages evidenced by isoenzyme mapping

U-937 represents a well established permanent human hematopoietic cell line. Electron microscopical and enzyme cytochemical studies as well as the analysis of surface glycoproteins have provided ample evidence for the monocytic origin of U-937. Upon stimulation with the tumour promotor 12-O-tetradecanoylphorbol-13-acetate (TPA), U-937 cells evolve into macrophage-like cells with phagocytic capacities. Since human blood monocytes (BM) are characterized by five acid esterase (AcE; EC 3.1.1.6) isoenzymes which are cell-specific in terms of isoelectric points (pI) and antigenicity, attempts were made in the present study to identify identical isoenzyme patterns in non- and TPA-stimulated U-937 cells. BM, cultured BM, non- and TPA-stimulated U-937 cells, as well as samples of resident human peritoneal macrophages (PM) as clearly-defined functional derivatives of BM, were subjected to isoenzyme analysis using isoelectric focusing (IEF). The five monocyte specific isoenzymes of AcE were identified in both populations of U-937. TPA-stimulated samples showed two additional bands, identical to those appearing in cultured BM after 4 days of glass-adherence and characteristic of resident human PM. Antisera raised against AcE of BM immunoprecipitated the two additional isoenzymes of TPA-stimulated U-937. It is concluded (1) the isoenzyme mapping of AcE documents the monocytic origin of U-937. (2) TPA-stimulation caricatures transformation of BM into resident tissue macrophages as far as pure morphology and AcE isoenzyme patterns are concerned. Thus, AcE isoenzyme mapping is apt for establishing reproducible and standardized criteria of different activation/differentiation states within the monocyte-macrophage lineage.

The production of immunoregulatory factors by a human macrophage-like cell line. I. Characterization of an inhibitor of lymphocyte DNA synthesis

Stimulation of the human histiocytic lymphoma, U937, with the lectins concanavalin A or phytohemagglutinin, results in the production of an inhibitor of mitogen-induced peripheral blood lymphocyte proliferation. This inhibitor of DNA synthesis (IDS) has an apparent molecular weight of approximately 65,000, is heat (56 degrees C) and acid (pH 2.0) labile, but is resistant to 10(-4) M 2-mercaptoethanol treatment. The mechanism of action is nontoxic and reversible within 24 hr of removal of the cells from IDS-containing supernatants. A variety of lymphoid and lymphoblastoid cell lines of B and T lymphocyte origin are sensitive to the effects of IDS. In contrast, the nonlymphoid cell lines HeLa, L929, MCF-7, and T47-D are unaffected by exposures to high concentrations of IDS preparations. The relationship of the IDS to other macrophage-derived inhibitory factors is discussed.

Malignant histiocytosis presenting as lethal midline granuloma: immunohistological study

Recent advances in immunology have revealed that the "histiocytic" lymphoma of Rappaport is a proliferation of transformed lymphocytes rather than true histiocytes, and that the malignant cells in malignant histiocytosis (MH) are truly transformed histiocytes. We previously reported cases of MH presenting as lethal midline granuloma (MH-LMG) utilising fresh tissue specimens for the detection of cytological markers in a small number of cases. The results showed the true histiocytic nature of the proliferating cells. In this study, paraffin-embedded specimens from 16 cases with MH-LMG were processed for immunoperoxidase procedures to confirm the true histiocytic nature of the proliferating cells. Five cases with nasal and paranasal lymphomas (ML) were also stained to test the usefulness of immunoperoxidase procedures for distinguishing the MH-LMG from ML. Results were as follows; proliferating cells in MH-LMG were histiocytic in nature, staining positive for lysozyme in MH-LMG in contrast to the negative staining in ML.

Variation in selectivity of tumor cell cytolysis by murine macrophages, macrophage-like cell lines and NK cells

Several murine tumor-cell lines were tested by isotope release assays for their susceptibility to lysis by either activated peritoneal macrophages (apMPh), macrophage-like (MPh-like) cell lines, or natural killer (NK) cells. The qualitative selectivity of tumor-cell lysis by these different effector cells was quite disparate. The rank order of target cell susceptibility to lysis by apMPh in 24 h assay was L5178Y greater than P815 approximately equal to RL male greater than YAC-1 approximately equal to MBL-2. This was seen regardless of whether peritoneal MPh (pMPh) were activated by LPS or poly I:C. Two MPh-like cell lines, PU-5R and FC-1, had a pattern of cytotoxic activity against these target cells that closely paralleled that associated with apMPh, although levels of reactivity differed quantitatively among the effector cells. In contrast, the MPh-like cell line RAW-264 expressed a qualitatively different pattern of target-cell selectivity, preferentially lysing MBL-2, which was relatively refractory to lysis by other MPh-like cell lines or apMPh in the 24 h cytolytic assay. When spontaneous or interferon (IFN)-augmented NK activity was measured against the same panel of target cells, the pattern of selectivity was qualitatively different from that observed for apMPh. The consistent rank order of susceptibility to lysis by NK cells was YAC-1 greater than RL male 1 greater than P815 approximately equal to L5178Y approximately equal to MBL-2. The characteristic patterns of target-cell selectivity for apMPh or NK cells were the same for all of the strains of mice tested. From the different selectivity patterns of apMPh and NK cells, it is concluded that lysis of target cells is not based solely on inherent sensitivity to cytolysis. Instead, selectivity of lysis is probably due to variations in expression of target-cell structures recognized by each type of effector cell, and/or in susceptibility to the lytic mechanism(s) of the various effector populations.

Armed human monocytes challenged with a sensitizing cancer extract release substances pharmacologically similar to leukotrienes

Human peripheral blood monocytes were highly enriched by adherence to plastic, armed with serum from cancer patients, and challenged separately and simultaneously with the sensitizing and unrelated cancer extracts. The response of the monocytes was to release a factor that inhibited leukocyte adherence (LAI) to glass. The macrophage-like cell line U937 released a similar factor when it was armed and challenged with the sensitizing cancer extract. The production of the factor was blocked by 10(-6) M ETYA and 10(-6) M NDGA but not by 10(-6) M indomethacin. Moreover, a competitive inhibitor of leukotriene function, 10(-6) M FPL 55712, blocked the LAI reaction mediated by the factor. Arylsulfatase destroyed its activity while depletion of the monocytes' cellular glutathione pool with CyH or Et2Mal stopped production of the mediator. Pure leukotrienes (C and D) in a dose-response fashion prevented the adherence of leukocytes to glass; the nonadherence of mononuclear cells was equal to that of polymorphonuclear cells. PGE2, if added to the leukocytes immediately before challenge with LTC or LTD, increased 1,000-fold the leukocytes' sensitivity to the leukotrienes. Paradoxically, if leukocytes were washed and exposed to PGE2 15 min after being challenged with leukotrienes, their normal glass-adherence property and the ability to respond again to LTD were restored. FPL 55712 blocked the effect of LTC and LTD from inhibiting the adherence of leukocytes to glass. The present study shows that human monocytes armed with cytophilic anti-tumor antibody, when challenged with the sensitizing cancer extract, release leukotriene(s) as shown by pharmacologic evidence, implying that monocytes may play an important inflammatory role in human cancer.

Immature megakaryocytes in the mouse: in vitro relationship to megakaryocyte progenitor cells and mature megakaryocytes

An assay describing conditions for the maturation of single immature megakaryocytes in vitro is reported. Enriched populations of small, relatively immature megakaryocytes have been found to develop into single, mature megakaryocytes by 60 hours in semisolid agar cultures. Continued incubation of these cells did not lead to the formation of colonies within 5-7 days. Maturation was indicated by increasing cell size and cytoplasmic and acetylcholinesterase content. Factors stimulating the development of immature megakaryocytes were found in preparations of human embryonic kidney cell-conditioned media (a source of in vivo Thrombopoietic Stimulatory Factor), peritoneal exudate cell-conditioned medium, lung-conditioned medium, or bone marrow cellular sources of activity (adherent cells or cells that sediment at 5-6 mm hr-1). Immature megakaryocytes cultured serum free responded to sources of an auxiliary megakaryocyte potentiating activity by developing into single, large megakaryocytes but did not respond to a megakaryocyte colony-stimulating factor devoid of detectable potentiator activity present in WEH1-3-conditioned medium. In contrast, serum-free proliferation of the megakaryocyte progenitor cell required both megakaryocyte colony-stimulating factor and the auxiliary potentiator activity. In the presence of megakaryocyte colony-stimulating factor alone, progenitor cells did not form colonies of easily detectable megakaryocytes. However, groups of cells comprised entirely of small acetylcholinesterase containing immature megakaryocytes were observed, thus establishing that megakaryocyte colony development passes through a stage of immature cells prior to detectable megakaryocyte development and that some acetylcholinesterase-containing cells can undergo cellular division.

Tissue factor-like activity of the human monocytic tumor cell line U937

Undisrupted cells of the human monocytic tumor cell line U937 have procoagulant activity that is Ca2+ dependent and is not demonstrable in Factor VII or Factor X deficient plasma. Furthermore, U937 cells when incubated with purified human Factor VII in the presence of Ca2+ and then repeatedly washed promoted coagulation of Factor VII deficient plasma in the absence of added tissue factor. Culture with endotoxin increased the procoagulant activity of U937 cells approximately 5-fold. In separate experiments, exposure to lymphokines obtained from phytohemagglutinin-stimulated lymphocytes enhanced the procoagulant activity of U937 cells 4 to 110-fold. Other cell lines (of myeloid and lymphoid origin) tested lacked the procoagulant activity found in U937 cells. These results indicate that the constitutive tissue factor-like activity of U937 cells resembles that of normal activated human monocytes.

Malignant histiocytosis with slow clinical course

Previously we reported that malignant histiocytosis presenting as lethal midline granuloma (MH-LMG) showed rapidly progressive course (mean survival 14 months). Because of the same biopsy findings of polymorphic cellular infiltrates (PCI), we considered that MH-LMG and midline malignant reticulosis (MMR) are similar disease. In this paper, we studied 5 cases with MH-LMG showing slow clinical course with more than 5 year survivals, and a similarity found in MH-LMG and MMR in which disseminated and localized disease are present, is discussed. Among clinical data, no abnormality in hematologic findings in MH-LMG with slow clinical course was the only different point from that with progressive course. Biopsy findings of PCI in which atypical histiocytes with positive reactions for lysozyme by immunoperoxidase procedures were present, were identical with those in MH-LMG with progressive course. Autopsy findings justified a diagnosis of MH. MH with slow clinical course seems to be identical with MMR showing localized lesion. Therefore a term MMR should be replaced by a term MH-LMG in the classification of LMG.

Infantile sarcoma with intracytoplasmic filamentous inclusions: distinctive tumor of possible histiocytic origin

This report describes four malignant tumors originating in infants, (one present at birth), for which a common origin is proposed. The common nature of these tumors was suggested by a remarkable similarity of histologic and ultrastructural features, including the presence of intracellular filamentous aggregates, as well as a shared aggressive clinical course consistent with sarcomatous origin. Two of these neoplasms arose within the kidney and were classified as "rhabdoid" sarcomas, according to the NWTS nomenclature. However, cells from these neoplasms could not be identified as muscular in origin. In culture, these cells demonstrated adherence to substratum, ability to phagocytose particles, and cell surface complement receptors. In addition, the renal tumors contained definite tumor cells positive for muramidase; the liver primary tumor contained only a limited number of such cells, which could not be interpreted as neoplastic. These findings suggest that among the "round-cell sarcomas" of infants and young children, a distinct, highly malignant form may be identified on clinical and morphologic grounds. The possibility that the tumor cells may be linked to the mononuclear phagocyte system was suggested, but not proved, and deserves further study.

Identification of a fourth class of proteins linked to the murine major histocompatibility complex

A series of proteins biochemically and genetically distinct from previously defined murine major histocompatibility complex class I and class II antigens is precipitated by a congeneic anti-H-2d antiserum. Sixteen such proteins have been defined, exhibiting a range of molecular weights (approximately 15,000-30,000) and isoelectric points (pI approximately 4-9). These proteins are not glycosylated, and they are probably not expressed at the cell surface. They are expressed most strongly in normal macrophages and macrophage cell lines and are also found in fibroblasts, B, T, and null cell lines. The genes controlling the expression of these proteins have been tentatively mapped within the H-2 complex, between the K and I-A subregions. Three alleles have been defined: mice of the H-2 haplotypes b and q possess a "null" allele, i.e., do not express any demonstrable protein product. Mice of the d haplotype cane be distinguished by their two-dimensional gel pattern from mice of all other positive H-2 types tested thus far (a, k, f, s, and ja).

Genetic analysis of the role of cAMP in mediating effects of interferon

The effects of interferon (IFN) on Fc receptor-mediated phagocytosis, intracellular cAMP levels, antiviral activity, and growth inhibition were analyzed in a cloned macrophage-like cell line, J774.2, and variants derived from it. Purified IFN increased Fc receptor-mediated phagocytosis in J774.2 cells, and in cAMP-responsive nonphagocytic variants but was without effect in cAMP-unresponsive nonphagocytic variants, in adenylate cyclase-deficient variants, and in cAMP-dependent protein kinase-deficient variants. Under conditions in which IFN augmented phagocytosis, it increased intracellular levels of cAMP. Parental cells were highly sensitive to IFN-mediated growth inhibition. In contrast, cAMP-dependent protein kinase-deficient variants were only 1/100th as sensitive to growth inhibition by IFN. All cell lines tested, both responsive and unresponsive to cAMP, were equally protected by IFN against infection with vesicular stomatitis virus, demonstrating that the antiviral state was independent of cAMP. These results indicate that, in transformed macrophages, stimulation of phagocytosis and inhibition of growth by IFN are mediated through intracellular cAMP, whereas the antiviral state induced by IFN is independent of cAMP.

Elastase of U-937 monocytelike cells. Comparisons with elastases derived from human monocytes and neutrophils and murine macrophagelike cells

As an approach to facilitating the understanding of proteinases associated with monocytes we have studied U-937 monocytelike cells. Elastase activity was identified in U-937 cell extracts and compared to monocyte elastase activity, neutrophil elastase, and the elastase activity from a continuous line of murine macrophagelike cells (P388D1). Serine proteinase activity which solubilized (14)C-labeled elastin accounted for >90% of the neutral proteinase activity of both U-937 cells and monocyte extracts. U-937 cell and monocyte elastase activities were similar catalytically, resembling neutrophil elastase. U-937 cells and monocytes showed other similarities: (a) both had activities reacting with [(3)H]diisopropylfluorophosphate that migrated in sodium dodecyl sulfate (SDS) polyacrylamide gels at approximately 30,000 and 60,000 daltons and (b) both contained material that cross-reacted with antiserum raised to neutrophil elastase. Preliminary characterization of U-937 cell elastase activity by affinity chromatography and ion-exchange chromatography suggested the presence of at least two distinct elastases. Minimal elastase activity was found in U-937 cell-conditioned medium, indicating that the activity is not spontaneously released by the cells. In contrast to the elastase activity associated with U-937 cells and monocytes, the elastase activity associated with P388D1 cells was a metalloproteinase and was found principally in the culture medium. These results indicate (a) U-937 cells will be useful for further investigation of proteinases associated with normal monocytes; (b) monocytes and U-937 cells contain material with catalytic and immunologic similarities to neutrophil elastase; (c) monocyte elastase activity differs from elastase activity secreted by murine macrophages and murine macrophagelike cells of the P388D1 line.

Molecules stimulating early red cell, granulocyte, macrophage, and megakaryocyte precursors in culture: similarity in size, hydrophobicity, and charge

Molecules in conditioned medium from stimulated lymphocyte populations or from certain cell lines are known to stimulate cells committed to various hemopoietic lineages as well as pluripotential cells to form colonies in culture. In this study, the relationship between molecules active on pluripotential cells and early cells committed to granulocyte, macrophage, megakaryocyte, or red cell production was explored using techniques of chemical separation. After separation on the basis of charge, or after sequential purification using methods of high resolving power based on hydrophobicity and size, these activities remained associated with one another. The observations provide support for a model which proposes that pluripotential hemopoietic precursor cells as well as their early committed progeny may all be responsive to a single lineage-indifferent factor. Responsiveness to "lineage-specific" factors such as erythropoietin is proposed to be a feature only of later cells after they have made the appropriate receptors as part of their differentiation program.

Biochemical and functional characterization of mature progeny purified from a myelomonocytic leukemia cell line

Comparative studies were performed on the cloned myelomonocytic leukemia cell line, WEHI-3B, and a subcloned line, WEHI-3BM6. WEHI-3BM6 cells were less responsive than WEHI-3B cells to differentiation factor (DF) present in the sera of mice injected with endotoxin (endotoxin serum, ES). WEHI-3BM6 cells produced only 8% monocytes after 6 days of incubation with ES compared with 68% monocytes produced by WEHI-3B cells. In the presence of ES the rate of differentiation of both cell lines was enhanced by the addition of actinomycin D (5 ng/ml) such that after 2 days of stimulation 62% of the cells were mature monocytes. Lysozyme content as well as the expression of alpha-napthyl acetate esterase were also increased by actinomycin D. As indicated by the shifts in modal fluoresence levels (209 vs 63), differentiating WEHI-3B cells showed an increase in the binding of an anti-neutrophil serum compared with untreated WEHI-3B cells. The binding of anti-neutrophil antibodies allowed the sorting of the mature monocytes from the blast cells in DF-treated WEHI-3B cells achieving a purity of 78%. Electrophoretic analysis of radiolabelled proteins from the cell extracts of WEHI-3B-derived monocytes showed close similarities to normal murine peritoneal macrophages and distinct differences from the protein profiles of purified murine peritoneal polymorphs. A protein of 75,000 mol, wt present in the polymorphs was absent from the WEHI-3B monocytes.

Differences in the regulation of megakaryocytopoiesis in the murine bone marrow and spleen

Murine splenic megakaryocytopoiesis has been analysed and compared to that of the bone marrow. Quantification of megakaryocytes by acetylcholinesterase staining indicated a reduction in the total numbers of megakaryocytes in the spleen, with the largest decrease being in the total numbers of immature megakaryocytes. On a per organ basis, the spleen also contained a lower number of the megakaryocyte progenitor cells (CFU-Mk) than the bone marrow. The splenic and bone marrow progenitor cells had similar in vitro responses to megakaryocyte colony-stimulating activities. However, the splenic progenitor cells developed a lower number of megakaryocytes per colony, compared to bone marrow. This lower number of cell divisions was not compensated by increased endomitotic activity, since the splenic colony megakaryocytes had a similar distribution of DNA to those derived from marrow megakaryocytes. Cell cycle analysis indicated that, in contrast to marrow cells, splenic megakaryocyte progenitor cells are a rapidly-cycling population. This change in cell cycle status, together with altered proportions of progenitor cells, immature and mature megakaryocytes, suggests that the regulation and kinetics of megakaryocyte development are different in spleen and bone marrow.

G-CSF: its relationship to leukemia differentiation-inducing activity and other hemopoietic regulators

The murine myelomonocytic leukemia WEHI-3B exists as differentiation-inducible (D+) and noninducible (D-) cell lines. Both lines produce a CSF species that stimulates exclusively the formation of neutrophil granulocyte colonies. This G-CSF copurifies with a mast cell growth factor but can be separated from M- and GM-CSF. NZB bone marrow is unresponsive to G-CSF stimulation. WEHI-3B D+ cells can induced to terminal granulocyte differentiation by a factor present in murine and human postendotoxin serum that is different from G-CSF present in WEHI-3B D+ or D- CM since the latter has little or no leukemia differentiation-inducing activity. Endotoxin treatment of C. parvum primed mice leads to simultaneous induction of serum activities with selective action on myeloid leukemic cells, a serum differentiation inducing activity and a leukemic colony inhibitory activity. These factors act synergistically to block leukemic stem cell self-renewal. The results suggest that a variety of inducible factors may have potent and selective antileukemic activity.

Fate of phase I and phase II Coxiella burnetii in several macrophage-like tumor cell lines

Several macrophage-like tumor cell lines of murine origin were exposed to phase I and phase II Coxiella burnetii, and the subsequent fate of the parasites was determined by electron and bright-field microscopy. Phase I C. burnetii proliferated within and established a persistent infection of P388D1, J774, and PU-5-IR cell lines but not of WEHI-3 and WEHI-274 cell lines. Phase II C. burnetii, however, entered into and persistently infected all five cell lines. The parasites proliferated within vacuoles. Macrophage cell lines persistently infected with phase I and phase II C. burnetii were maintained for over 200 and 100 days, respectively. Within P388D1 cells, the phase I C. burnetii converted, in part, to phase II; phase II organisms remained in the phase II state. The differential fate of the two rickettsial phases after exposure to the WEHI-3 and WEHI-274 cells may be attributable to surface differences such as lipopolysaccharide content.

A cytochemical and immunohistochemical approach to malignant histiocytosis

Malignant histiocytosis (MH) is a true histiocytic disorder, whose identification is still based on too broad morphologic criteria. Using routine histology, cytochemical and immunohistochemical techniques on involved lymph nodes, 15 cases of MH have been investigated. Pleomorphism and cellular atypia, phagocytosis, lack of cohesiveness between proliferating cells, sinusoidal involvement, and plasmacytic infiltrate were the most common histologic features. MGG-stained imprints from 14 cases showed a composite tumor population mainly consisting of histiocyte-appearing cells, poorly differentiated atypical cells, and multinucleated giant cells. These cells, irrespective of cytologic features, revealed a diffuse, moderately to strongly positive reaction with acid phosphatase and nonspecific esterase. Naphthol-AS-D-chloroacetate esterase, Sudan black B, alkaline phosphatase, and beta-glucuronidase reactions were completely negative. Immunoperoxidase studies in 11 cases demonstrated that tumor cells stained positively for both kappa and lambda chains. These cells were also positive for albumin. Polytypic staining for IgG was observed in two cases, and a weak staining for lysozyme was found in two other nodes. Global results confirm the value of these studies for functional profile determination of MH proliferating cells. A combined approach using a variety of cytochemical and immunohistochemical techniques should be routinely considered in MH as useful additional studies for a more precise diagnostic definition of the disease.

The distribution of Helix pomatia lectin receptors on mouse lymphoid cells and other tissues

The distribution of receptors for the Helix pomatia lectin on mouse lymphoid cells and other tissues was investigated. Using a sensitive rosetting assay combined with immunofluorescence, lectin receptors were found on the membrane of approximately 90% of peripheral T lymphocytes, 75% of thymocytes, 30% of bone marrow cells, 20% of nude spleen cells, 15-50% of peritoneal exudate macrophages, and a subpopulation of peritoneal exudate mast cells. The Thy-1-positive nude spleen cells were predominantly Helix lectin receptor-negative. Approximately 5% of B lymphocytes were weakly positive, and neutrophils were negative. Receptors were present also on a subpopulation of cells of a fibroblast cell line and in acetone powder from the liver and, at a lower level, from the kidney and brain. Membrane receptors on all cell types were partially detectable without neuraminidase treatment of the cells. Two methods of fractionating Helix lextin-positive cells were employed, which gave significantly different results. By rosetting and depletion using density fractionation, T cell mitogen responses were abolished, while B cell mitogen responses, T cell cytotoxicity, and natural killer cytotoxicity were only slightly affected, if at all, Helix lectin-agarose column fractionation seemed more sensitive, in that essentially all natural kill cells bound to the column, as well as considerable number of B lymphocytes. Cytotoxic T cells were heterogeneous; roughly half were not bound, but the remainder were bound and eluted.

Continuous lines of basophil/mast cells derived from normal mouse bone marrow

Nonadherent tissue culture cell lines were established from normal bone marrow of a variety of mouse strains. The lines possessed morphological and histochemical markers of the basophil/mast cell and contained committed stem cells for metachromatic cells. Their derivation from normal marrow and their lack of tumorigenicity despite long-term culture makes these cell lines potentially important for studies of the mechanisms of allergic reactions and inflammation as well as the differentiation pathways involving this subset of hematopoietic cells.

Induction of malignant lymphoreticular cell line which displays spontaneous killer-cell activity

The origin and properties of a new malignant "spontaneous killer" cell line are described. The tumor, known as M9-78, was produced by treatment of tissue cultures consisting mostly of dividing DBA/2 mouse macrophages with the chemical carcinogen, 3-methylcholanthrene. Logarithmic phase cultures were treated for 6 days followed by further culture for 1 month in the absence of carcinogen. Subcutaneous injection of normal DBA/2 mice with 2.0 X 10(5) cells led to the formation of palpable tumors at the site of inoculation within 14 days; the tumors grew progressively and were highly metastatic. The malignant cells, though Fc-receptor-positive, did not possess many other properties normally associated with macrophages; morphologically, they bore a strong resemblance to bone-marrow-derived promonocytes. Because promonocytes have been shown previously to possess both antibody-dependent killer (K) cell as well as antibody-independent spontaneous killer-cell function, the M9-78 cells were tested for these biologic activities. The following results were obtained: (1) adherent, but not non-adherent, M9-78 tissue culture cells spontaneously killed a wide variety of (though not all) tumor-cell-line targets in long-term (18-24 h) 51Cr release, whereas no killing was seen in short (4 h) assays; (2) the cells were not capable of killing nucleated targets by antibody-dependent cell-mediated cytotoxicity; (3) a number of clones were obtained and tested for spontaneous killer-cell activity: some were highly active, whereas others were negative, with different patterns of specificity being evident; (4) the clones were unstable; (5) the pattern of target killing, when compared to normal spleen control NK cells, suggested the M9-78 cells were similar to activated macrophages or promonocytes in their target selectivity, although no definitive evidence was obtained which could implicate a promonocyte or monocyte origin for the cells.