Lipoprotein lipase in heart cell cultures is suppressed by bacterial lipopolysaccharide: an effect mediated by production of tumor necrosis factor

Exposure of rat heart cell cultures, consisting mainly of nonbeating mesenchymal cells, to 50 ng/ml of bacterial lipopolysaccharide (LPS) for 24 h resulted in a more than 80% reduction in lipoprotein lipase activity. The loss of enzymic activity was accompanied by a concomitant reduction in enzyme protein, as shown by immunoblotting. Addition of LPS to the culture medium resulted also in the production of tumor necrosis factor (TNF), and the fall in lipoprotein lipase in LPS-treated cultures could be prevented by an antibody to TNF. Addition of recombinant human TNF to the heart cell cultures also depressed lipoprotein lipase activity. LPS treatment of preadipocytes in culture resulted in a fall in lipoprotein lipase activity and TNF production. Since TNF is known as a macrophage product, the cultures were tested for phagocytic capacity, and only 0.2-1.3% of the cells were shown to engulf Staphylococcus albus. Immunofluorescent staining with monoclonal antibodies OX-1, which identify leukocyte common antigen, was negative, and only 0.1 +/- 0.07% of the cells were positive after staining with OX-42 antibody to iC3b receptor. Both antibodies stained more than 98% of rat peritoneal macrophages used as controls. Since LPS treatment of macrophages at numbers comparable to or exceeding the number of phagocytic cells present in the heart cell cultures did not induce measurable amounts of TNF, it is suggested that in the heart cell cultures, TNF may be produced by cells other than macrophages.

Establishment and characterization of murine bone marrow-derived spontaneously immortalized cell lines and clones expressing properties of normal macrophages

Murine bone marrow (BM) cells were cultivated on bacteriological grade culture dishes (BCD) in liquid medium containing L-cell-conditioned medium (LCM). The first month of rapid exponential multiplication was always followed by an interim phase of slow growth, and then by continuous proliferation. These established lines were called Jerusalem bone marrow macrophages (JBM phi). One of these, which had been derived from a C3H/Crg1 female mouse and was designated JBM phi 1.1, was studied in more detail. Its cloning efficiency when grown in LCM-containing soft agar was 65%. Of several clones isolated, one, C1.26, was selected for further cultivation and propagated for about 600 days. Cells from all cultures were surface adherent with limited proliferative capacity on tissue culture plastic. The properties displayed by all cells in a culture or clone include a typical macrophage (M phi)-like morphology, effective ingestion of killed bacteria and zymosan, staining for nonspecific esterase, and expression of Fc receptors and of F4/80 surface antigen. Addition of lymphokine (LK) induced Ia antigen expression on a high percentage of the cells. The JBM phi 1.1 cells also secreted high levels of lysozyme, produced a zymosan-induced respiratory burst, and, upon addition of lipopolysaccharide (LPS), released interleukin-1 and tumor necrosis factor. Efficient tumoricidal activity could be induced by LK and LPS. No evidence for the production of colony-stimulating factors, even in the presence of LPS, could be found. The JBM phi 1.1 or C1.26 cells did not develop into tumors following subcutaneous injection in x-irradiated syngeneic or in nu/nu mice and were also incapable of growing in soft agar without LCM. All the properties studied were expressed at similar levels by the "young" BM-derived M phi during their first exponential growth phase, as well as by other JBM phi lines and clones. It is concluded that the established JBM phi lines consist of homogeneous cell populations which, according to all markers and functions studied, could be classified as non-activated, functional, and mature M phi, resembling in all aspects BM-derived M phi during their first few weeks of cultivation. This shows that cell lines expressing properties of normal M phi may develop spontaneously by continuous cultivation of BM cells in growth factor-containing liquid medium on BCD.(ABSTRACT TRUNCATED AT 400 WORDS)

Dual effect of lectins on macrophages: potentiation of bacterial uptake and suppression of bactericidal activity

Pretreatment of murine bone marrow-derived macrophages with wheat germ agglutinin (WGA) and concanavalin A (Con A) markedly enhanced the uptake of Staphylococcus aureus H and Escherichia coli 08, respectively. Pretreatment of the respective bacteria with these lectins also greatly increased their uptake by the macrophages. An increase of up to 40-fold in uptake of E. coli 08 by the macrophages was observed following their pretreatment with Con A in the absence of serum and at a low temperature. On the other hand, pretreatment of macrophages with either WGA or Con A suppressed very markedly or abolished completely their bactericidal activity against S. aureus H and E. coli 08, respectively. As macrophage chemiluminescence reactions to zymosan were also very greatly suppressed following pretreatment with WGA and Con A, we suggest that these lectins suppressed macrophage bactericidal activity by inhibiting reactions involving chemiluminescence.

Correlation of macrophage-mediated tumor-cell lysis with the production of macrophage cytolytic factor (CF). Preliminary characterization of a factor inhibiting CF production

Macrophage-mediated cytolysis of thymidine-prelabelled murine A9 fibrosarcoma cells was compared to the level of cytolytic factor (CF) present in the cultures by assaying supernatant aliquots on actinomycin (AcD)-treated A9 fibrosarcoma cells. A good correlation between the level of A9 killing and CF titer was observed when different concentrations of lipopolysaccharide (LPS) were added to various macrophage populations: murine peritoneal cells, short-term bone-marrow (BM)-derived macrophages and JBM phi macrophage lines. Optimal A9 killing and CF secretion, equivalent to the killing of about 1000 AcD-pretreated A9 cells by a single macrophage, were obtained following activation of JBM phi by LPS. CF production by BM-derived macrophages was enhanced in serum-free medium when compared to its release in the presence of fetal calf serum. The LPS-activated macrophages could be restimulated by the activating agent to produce CF following one week of propagation in the absence of LPS. On the other hand, CF activity was absent from the supernatants of activated macrophages co-cultured with normal embryonic fibroblasts, which are resistant to macrophage-mediated killing. This effect could be attributed to a factor, secreted by normal fibroblasts but not by A9 cells, which suppressed CF release from the activated macrophages. Our data strongly support earlier observations, suggesting that CF [which appears to resemble the tumor necrosis factor (TNF)] is responsible for LPS-induced macrophage-mediated tumor cell lysis. It is suggested that suppression of the latter process by the fibroblast-derived factor proceeds via inhibition of CF/TNF production from the macrophage.

Suppression of both macrophage-mediated tumor cell lysis and cytolytic factor production by a factor (CIF) derived from normal embryonic fibroblasts

We had previously established a murine bone marrow-derived cell line, designated JBM phi 1.1, which displayed properties of normal macrophages, including the ability to perform macrophage-mediated cytolysis. It was also found that these cells could be induced by lipopolysaccharide (LPS) to produce reproducibly high levels of a cytolytic factor (CF) resembling tumor necrosis factor (TNF). This cell line was therefore selected for further studies on macrophage-mediated tumor cell lysis and CF production. Moreover, the CF production during incubation with LPS was higher in the absence of serum than in its presence, with a maximum at days 2-3 following the addition of LPS. A factor inhibitory to CF production (CIF) was detected in our laboratory in the supernatant of embryonic fibroblast cultures. We established the experimental conditions required for the optimal production and suppressive effect of CIF. High levels of CIF activity were obtained under conditions that promote fibroblast proliferation. Addition of embryonic fibroblast culture supernatant to the macrophages shortly before LPS suppressed both LPS-induced CF production and tumoricidal activity. CIF did not affect macrophage protein synthesis in the presence or absence of LPS. However, LPS-induced interleukin 1 release was partially (55%) suppressed by embryonic fibroblast culture supernatant. Our results show that CIF does not exert a general inactivating effect on the macrophages, although it may possibly affect other functions in addition to CF production and tumor cell lysis. The strong inhibition of both the latter properties further indicates that TNF-like CF is an important mediator in macrophage-mediated tumor cell lysis.

Thymus-derived macrophages in long-term culture: release of IL-1, stimulation of MLR and expression of tumoricidal activity

The present report examines the behaviour of a slowly proliferating pure population of thymus-derived macrophages in long-term culture, regarding their ability to secrete interleukin-1 (IL-1) and prostaglandin E2 (PGE2), to stimulate a mixed leucocyte reaction (MLR) and to lyse tumour cells in vitro. Following stimulation with LPS, high levels of IL-1 were released to the medium. IL-1 release was significantly augmented by the addition of indomethacin during stimulation. Thymus-derived macrophages constitutively secreted significant levels of PGE2. These cells served as excellent stimulators in a one-way MLR, substantiating the claim that pure populations of macrophages effectively stimulate an allogeneic response in vitro. Thymus-derived macrophages showed tumoricidal activity following activation with either high concentrations of LPS or suboptimal concentrations of LPS and T-cell lymphokine. These findings portray a close interrelationship and reciprocal regulation between thymus-derived macrophages and T lymphocytes.

Lysis of primitive teratocarcinoma cells by non-activated macrophages

The capacity of non-activated murine thioglycollate-elicited macrophages and bone marrow-derived macrophages to lyse primitive F9 teratocarcinoma cells lacking H-2 antigens was investigated. Both populations of non-activated macrophages killed F9 cells efficiently whereas they were not cytolytic against murine fibrosarcoma targets. In vitro activation by lipopolysaccharide induced the macrophages to lyse fibrosarcoma cells but did not significantly increase the level of cytolysis against F9. These results are consistent with the hypothesis that the absence of H-2 expression on target cells may serve as a signal for macrophage "foreign" recognition and cytolysis.

Antigen presentation by proliferating thymic macrophages to A (T,G)-A-L specific T cell line in an H-2 restricted manner

Long-term cultures of murine homogeneous populations of Ia-bearing thymus-derived murine macrophages were tested for their ability to present antigen to a (T,G)-A-L specific IL-2-dependent continuous T cell line. Thymus-derived macrophages, with and without pretreatment for Ia induction, triggered efficiently antigen-specific T cell proliferation in an MHC restricted way. This experimental system, consisting of two normal proliferating homogeneous populations of macrophages and antigen specific T cells, provides an ideal tool for studying the mechanism of antigen presentation to T cells and for elucidation of the role of macrophages in T-B cell collaboration for antibody production.

Studies on the mechanism of macrophage-mediated tumor cell lysis induced by Mycoplasma orale

Following our previous demonstration that both viable and heat-killed Mycoplasma orale induce selective tumor cell killing by murine peritoneal macrophages, further investigations reported here showed that also macrophages from a continuously proliferating cell line established from long-term cultures of murine bone marrow explants can effectively be induced by the heat-killed mycoplasmas to express cytolysis. The use of single-cell suspensions of M. orale from a 0.45-micron filtrate or following either sonication or treatment with DNase did not significantly affect the level of cytolysis. Minute quantities of M. orale acted synergistically with ineffectively low levels of either lymphokines (LK) or lipopolysaccharide (LPS) to produce killing. The exceptional resistance of M109 lung adenocarcinoma cells to macrophage-mediated killing induced by LK and LPS, as previously reported by us, could not be overcome by the addition of M. orale. These data appear to indicate a mechanism of macrophage activation by M. orale similar to that caused by LPS.

Wheat germ agglutinin potentiates uptake of bacteria by murine peritoneal macrophages

Exposure of thioglycollate-elicited murine peritoneal macrophages to wheat germ agglutinin (WGA) increased markedly the uptake of six different bacteria, which have surface receptors for the lectin. Uptake of Staphylococcus aureus H was higher by 3-5-fold, of S. aureus 52A2 by 1.8-fold, of S. aureus 52A5 by 1.7-fold, of S. albus by 2.3-fold, of Shigella flexneri by 6-fold and of Micrococcus luteus by 6.5-fold. Klebsiella pneumoniae, devoid of receptors for WGA, was not phagocytosed following pretreatment of macrophages with the lectin. Pretreatment of the bacteria with the lectin also resulted, in most cases, in an increase in phagocytosis. Interaction of WGA with the macrophages and with the bacteria, as well as the potentiation of phagocytosis, was abolished by tri-N-acetylchitotriose, a saccharide that binds specifically to WGA, but not by monosaccharides which do not interact with this lectin. With non-elicited macrophages, enhancement of phagocytosis by WGA was less pronounced, probably because of the higher number of lectin-binding sites (5-fold) on the elicited cells. Peanut agglutinin and soybean agglutinin, that bind to macrophages but not to the bacteria studied, lack the ability to potentiate phagocytosis. Macrophage surface sugars thus appear to play an important role in phagocytosis by serving as receptors for lectins that form bridges between the macrophages and the microorganisms.

Cultivation, proliferation and characterization of thymic macrophages

Successful long-term culture of murine thymic macrophages was achieved by plating adherent thymic cells, in the presence of L cell-conditioned medium, on dishes coated with an extracellular matrix. Adherent thymic cells in normal conditions of in-vitro culture do not proliferate. Those maintained on plastic tissue-culture dishes, and exposed to L cell-conditioned medium, proliferate slowly to a limited degree and form very small colonies. In contrast, when cultured in dishes coated with an extracellular matrix formed by corneal endothelial cells, in the presence of L cell-conditioned medium, adherent thymic cells proliferate rapidly and after 12-21 days in culture form large colonies (about 3-5 mm in diameter). The proliferating cells were identified to be mononuclear phagocytes by their morphological appearance, their ability to ingest both bacteria and antibody-coated erythrocytes and by their nonspecific esterase activity. These cells were also shown to exhibit cell surface antigens that are characteristic of differentiated macrophages, e.g. Fc receptors and the specific macrophage cell surface marker F4/80. A high percentage of these cultured cells were found to bear I-A antigens. The adherent thymic mononuclear phagocytes could be trypsinized and passaged while maintaining both their ability to proliferate and their specific macrophage characteristics for a period of 70 days. Thus, monocyte-macrophage stem cells ae present in the thymus, and under appropriate in-vitro conditions, can be made to proliferate and mature to I-A-bearing macrophages.

Induction of macrophage-mediated cytolysis of neoplastic cells by mycoplasmas

Unexpected cytolysis was encountered when nonactivated murine peritoneal macrophages were cultured with [3H]TdR-prelabeled syngeneic or allogeneic tumor cells at a 10:1 ratio. The level of specific cytolysis reached 70% within 48 hr of cocultivation. Similar killing was observed whether the macrophages were derived from untreated, thioglycollate-treated, or germ-free mice. Cytolytic activity was also demonstrated when bone marrow-derived or peritoneal macrophages from 9- and 5-day in vitro cultures, respectively, were employed rather than freshly harvested peritoneal macrophages. Thus, the macrophage-mediated killing was neither the result of in vivo preactivation nor a consequence of the presence of lymphocytes in the assay. Moreover, macrophages derived from different strains caused similar effects. Our study revealed that the neoplastic target cell cultures susceptible to cytolysis by nonactivated macrophages were contaminated with mycoplasma. A mycoplasma was isolated from the supernatant of a culture of the A9HT fibrosarcoma line, identified as Mycoplasma orale, and cultivated. Addition of viable mycoplasma from that isolate to mixed cultures of thioglycollate-elicited macrophages and [3H]TdR-prelabeled mycoplasma-free target cells resulted in specific cytolysis of transformed A9 cells, but not of normal mouse fibroblasts. The level of macrophage-dependent cytolysis correlated with the number of viable mycoplasma cells added and was higher than that attained by activation with LPS at optimal concentration. Similar specific cytolysis was observed with heat-killed mycoplasmas. Our results demonstrate that mycoplasmas may cause selective macrophage-mediated cytolysis of neoplastic but not of normal target cells, perhaps via activation of the macrophages. It is suggested that undetected infection of experimental systems by mycoplasmas may account for some reports on lysis of neoplastic cells by nonactivated macrophages.

Mast cell differentiation depends on T cells and granule synthesis on fibroblasts

Mast cell differentiation was generated in the following three experimental situations: (i) infection of mice with Schistosoma Mansoni or with Nippostrongylus brasiliensis and growth of the lymph node cells in the presence of the corresponding helminth antigen; (ii) immunization with horse serum and growth of blood and lymph node cells in the presence of the horse serum; (iii) exposure of T-cell-depleted suspensions of lymph node cells from unimmunized mice to T-cell factor (TCF) released into medium of the young cultures of (i) and (ii). This differentiation was also obtained when lymph node cells from athymic nude mice were exposed to TCF. The cell suspensions were plated on X-irradiated fibroblast monolayers prepared from embryonic mouse skin. Screening of the suspensions before plating on the fibroblasts in culture revealed no young forms of mast cells, and none were present in culture of nude mice lymph node cells maintained without TCF. Primordial appearance of metachromatic granules generally in the golgi zone was first seen in many 'large lymphoid cells' as early as 18 hr after plating. This was followed by increase in the cytoplasm volume, increase in granule number and mitosis, ending at 10-18 days with homogeneous populations of mature mast cells. When the mesenteric lymph node cells from mice infected with the helminths were grown in the absence of fibroblasts but in the presence of the antigen, homogeneous populations of cells with extended cytoplasm, filled with unstained vacuoles developed during days 7-13. These cells did not contain histamine (or at most 0.2 microgram per 10(6) vacuolated cells). When these cells were plated on fibroblast monolayers clear granule formation in all the vacuoles was seen 2 days later. It increased progressively in size and staining intensity, until the vacuoles transformed into typical mast cell granules. By the fourth day the vacuolated cells attained the typical mast cell morphology and the histamine content greatly increased (from 0.12 microgram per 10(6) vacuolated cells to 3.02 micrograms per 10(6) mast cells). These mast cells were readily degranulated by monoclonal anti-DNP-BSA IgE, and the antigen, releasing 90% of the histamine. The study shows that mucosal mast cells formation from 'large lymphoid-like' cells present in the blood and in the lymph, is stimulated by TCF. The condensation of the metachromatic material and histamine synthesis depends on other cells, presumably fibroblasts which comprise the principal cell in the embryonic skin monolayers. The mechanism of the fibroblast influence is not yet known.

Recognition and lysis of altered-self cells by macrophages. I. Modification of target cells by 2,4,6-trinitrobenzene sulphonic acid

Peritoneal exudate macrophages from normal, untreated or thioglycollate-elicited mice, lysed syngeneic fibroblasts and lymphoblasts modified by 2,4,6-trinitrobenzene sulphonic acid (TNBS) in vitro. Optimal lysis of the hapten-modified cells by elicited macrophages was usually seen after 18 hr of co-cultivation at E:T ratios of 10:1-30:1. Cytotoxicity was expressed by macrophages depleted of T cells, and was not potentiated by LPS. Allogeneic TNBS-modified cells were lysed by non-immune, non-activated macrophages to the same extent as syngeneic modified targets, indicating that genetic restriction does not appear to play a role in macrophage-mediated cytolysis of TNBS-modified cells.

Non-immunological recognition and killing of xenogeneic cells by macrophages. III. Destruction of fish cells by murine macrophages

Non-immune non-activated murine peritoneal macrophage killed in vitro fish (Cyprinus carpio) PHA-induced lymphoblasts. Addition of PHA and WGA to effector-target cell cultures did not potentiate the killing. This killing (xenolysis) was expressed by non-elicited and thioglycollate-elicited macrophages as well as by macrophages depleted of lymphocytes. It is suggested that mammalian macrophages have a xenolytic potential towards phylogenetically distant species which is analogous to the capacity of invertebrate phagocytes to destroy xenografts.

Non-immunological recognition and killing of xenogeneic cells by macrophages. II. Mechanism of killing

Macrophages are cytotoxic to chicken embryonic fibroblasts without either previous activation or lymphocyte assistance. This cytotoxic activity (xenolysis) is expressed by non-activated macrophages from athymic mice as well as by pure macrophage populations. Neither macrophage lysate nor supernatants of macrophages cultivated with fibroblasts cause xenolysis. Unlike macrophage tumoricidal activity, killing of xenogeneic cells is not dependent on specific serum factors and is expressed by macrophages from a lipopolysaccharide (LPS) unresponsive strain (C3H/HeJ). Xenolysis is expressed also by trypsin-treated macrophages and by macrophages from 5-day-old cultures. Killing of chicken fibroblasts by macrophages is not affected by hydrocortisone (100 micrograms/ml) gold salt (1 mg/ml) and colchicine (100 micrograms/ml). On the other hand, cytochalasin B (10 micrograms/ml) completely abolishes the killing, probably by interfering with macrophage mobility and extension of filopodia toward the targets. It is suggested that the xenolytic activity of macrophages represents a primitive trait of phagocytes which assists the body in defence against multicellular parasites.

Non-immunological recognition and killing of xenogeneic cells by macrophages. I. Repertoire of recognition

Non-immune non-activated mouse peritoneal macrophages efficiently kill in vitro xenogeneic fibroblasts from various avian species (xenolysis). The killing was less effective for rat and human fibroblasts. Macrophages of all inbred strains tested demonstrated xenolytic activity although they differed in destruction efficiency. Recognition and killing of target fibroblasts were not dependent on the presence of Ca++ and Mg++. Lysis of SPEFAS chicken fibroblasts free of viral antigen expression (gs-chf-) suggests that foreign recognition by macrophages does not involve viruses. Administration of anti-H-2 antiserum and of rabbit anti-macrophage serum (AMS) as well as addition of various carbohydrates or their derivatives to macrophages interacted with fibroblasts, failed either to block or identify foreign recognition sites on macrophages. Morphological studies by scanning electron microscopy showed protrusions of macrophage filopodia unidirected to the target xenogeneic fibroblast.

Mouse macrophage functions under the influence of factors released by spleen cells preincubated with the methanol extraction residue (MER) tubercle bacillus fraction

Exposure of mouse peritoneal macrophages in vitro to the nonspecific immunomodulator MER (methanol extraction residue fraction of phenol killed, acetone washed tubercle bacilli) failed to heighten their phagocytic and bacteriostatic activities toward Staphylococcus albus, even when amounts of the agent below the threshold of gross toxicity were employed. In contrast, exposure of such macrophages to supernatants of whole splenocyte suspensions that had been obtained from normal donors and were incubated with MER resulted in consistent potentiation of both phagocytosis and bacteriostasis. The findings suggest that the MER effect on macrophages function is mediated, in this system, by soluble lymphocyte product(s).

Enhanced polymorphonuclear chemotaxis - a common feature of diseases responsive to colchicine

Increased chemotactic activity of peripheral polymorphonuclear (PMN) cells has been described in disease states of different etiology and may represent a common pathway in the generation of an inflammatory reaction. The suppressive effect of colchicine on PMN chemotaxis may explain its effect in apparently unrelated disorders.

Artificial binding of macrophages to syngeneic cells elicits cytostasis but not cytolysis

Artificial binding of mouse peritoneal macrophages to syngeneic embryonic fibroblasts by means of rabbit anti-mouse anti-macrophage serum or Con-canavalin A inhibited the proliferation of syngeneic target cells without destroying them. It is suggested that an intimate membranal contact between macrophages and target cells triggered cytostasis, whereas cytotoxicity requires an additional step of foreign recognition.

Leukocyte chemotaxis in recurrent polyserositis (familial Mediterranean fever)

Polymorphonuclear leukocyte chemotaxis was investigated in 35 patients with recurrent polyserositis during attacks and during spontaneous or colchicine-induced remissions. Chemotaxis was found to be unchanged in the attack-free period in untreated patients, increased by about 50% during attacks, and decreased by about 50% during colchicine treatment.

Effect of colchicine on polymorphonuclear leucocyte chemotaxis in human volunteers

1 The effect of colchicine on polymorphonuclear leucocyte chemotaxis was assessed in eight healthy volunteers. Four of them received 1.0 mg colchicine and the other four received placebo daily for 8 successive days. 2 Chemotaxis decreased significantly within 24 h of the ingestion of colchicine; the values remained low throughout the 8 days of treatment and returned to normal within 48 h of cessation of medication. 3 There were no significant changes in the placebo treated subjects.

Phagocyte functions in familial Mediterranean fever

Monocytes derived from peripheral blood of patients with familial Mediterranean fever (F.M.F.) demonstrated lower phagocytic capacity for Shigella flexneri and depressed bactericidal activity against S. albus when compared to monocytes from healthy individuals. Treatment of patients with colchicine did not alter these functions. On the other hand, chemokinesis of PMN of F.M.F. patients was enhanced especially during attacks. Colchicine treatment decreased significantly the PMN chemotactic migration.