Production of a factor (CIF) from normal fibroblast cells inhibiting tumor necrosis factor/cachectin production.

Murine embryonic fibroblast cells produce a factor designated cytotoxin-inhibiting factor (CIF) which inhibits tumor necrosis factor (TNF) and interleukin 1 production as well as tumoricidal activity by lipopolysaccharide-activated macrophages. This study determines the physiologic conditions of CIF production in serum-free medium. CIF production was largely dependent upon the presence of lipopolysaccharide. A quantitative correlation between fibroblast cell number, lipopolysaccharide concentration, and incubation time was established. Evidence is presented that CIF inhibited the production or release of TNF. CIF did not destroy TNF after production and release nor did it sequester secreted TNF. The supernatant fluids which inhibited TNF production did not suppress the capability of resting macrophages to phagocytize opsonized sheep erythrocytes, suggesting that only functions expressed in the activated state are inhibited.

Macrophage activation by the polysaccharide arabinogalactan isolated from plant cell cultures of Echinacea purpurea.

In this study, acidic arabinogalactan, a highly purified polysaccharide from plant cell cultures of Echinacea purpurea, with a molecular weight of 75,000, was effective in activating macrophages to cytotoxicity against tumor cells and micro-organisms (Leishmania enriettii). Furthermore, this polysaccharide induced macrophages to produce tumor necrosis factor (TNF-alpha), interleukin-1 (IL-1), and interferon-beta 2. Arabinogalactan did not activate B cells and did not induce T cells to produce interleukin-2, interferon-beta 2, or interferon-gamma, but it did induce a slight increase in T-cell proliferation. When injected ip, this agent stimulated macrophages, a finding that may have therapeutic implications in the defense against tumors and infectious diseases.

Tumour necrosis factor.

Tumour necrosis factor was originally thought to kill tumour cells but not normal cells and to be a principal mediator in macrophage-mediated killing of tumour cells. It is now known to have a broad spectrum of additional activity ranging from regulatory effects on normal cells to inhibitory effects on viruses and parasites.

Poliovirus retention in soil columns after application of chemical- and polyelectrolyte-conditioned dewatered sludges.

The transport of poliovirus type 1 (strain LSc) was studied in Red Bay sandy loam columns that were treated with chemical- or polyelectrolyte-conditioned dewatered sludges and then leached with natural rainwater under saturated flow conditions. Poliovirus was concentrated in the alum and ferric chloride sludges that were produced following the flocculation of virus-seeded raw sewage. Virtually complete inactivation of the virus was observed following the flocculation of raw sewage or the stabilization of alum and ferric chloride sludges with lime at pH 11.5. Poliovirus was also concentrated in polyelectrolyte-conditioned dewatered sludge that was produced from virus-seeded, anaerobically digested sludge. Despite the saturated flow conditions for a sustained period, no viruses were detected in the leachates of the soil columns that were treated with these chemical and chemically treated sludges. Since the viruses were mostly associated with the solids in these sludge samples, it is believed that they were immobilized along with the sludge solids in the top portion of the soil columns.

Cell-associated tumor necrosis factor (TNF) as a killing mechanism of activated cytotoxic macrophages.

Different macrophage populations were investigated for their abilities to secrete tumor necrosis factor (TNF) and to lyse TNF-susceptible tumor cells. In this way we could demonstrate that TNF-secretion, although a feature of all activated macrophage populations, is no absolute requirement for the killing of the TNF-sensitive Wehi 164 target. Macrophage cytotoxicity against this cell but not against the TNF-resistant P815 mastocytoma, was completely inhibitable by a specific anti-TNF serum also in the absence of measurable secreted TNF. Moreover the TNF-dependent lysis of tumor cells could also be performed by activated macrophages that had been fixed with paraformaldehyde before the addition of the target cells. In the indirect radioimmunoassay, TNF could be demonstrated on the surface of fixed effector cells. Our results must be interpreted in terms of membrane-associated TNF as the lytic principle for TNF-susceptible tumor cells.

Gamma interferon priming of mouse and human macrophages for induction of tumor necrosis factor production by bacterial lipopolysaccharide.

Priming of macrophages from both murine and human sources by recombinant immune interferons from Escherichia coli (r-IFN-gamma s) and activation by lipopolysaccharide (LPS) resulted in the production of tumor necrosis factor (TNF). r-IFN-gamma alone did not induce TNF production by macrophages; for this to occur, the second signal provided by small amounts (nanograms) of LPS was required. The small amounts of LPS alone were insufficient to activate the macrophages for TNF production. Priming by r-IFN-gamma was not necessary when larger amounts of LPS were employed, although an enhancement of yield resulted. Priming could also be demonstrated in vivo. Inoculation of r-IFN-gamma into mice resulted in increased yields of TNF following LPS challenge 12 hours later.

Natural production and release of tumour necrosis factor.

Tumour necrosis factor (TNF) was first described as an oncolytic factor found in sera of animals injected (primed) with reticuloendothelial stimulators and subsequently (days later) given lipopolysaccharide (LPS). TNF is not found in the serum of 'primed' animals but can be found in animals given LPS alone when sensitive assays are employed. TNF appears almost immediately upon LPS injection, reaches a maximum from about 1.5-2 hours and disappears rapidly thereafter, and is almost undetectable by 4-6 hours. When such mice are injected again with LPS, they are unresponsive (tolerized) and do not produce TNF again, at least for seven days. Other unrelated substances, such as muramyl dipeptide, viruses and mitogens, also induce TNF production. A high percentage of patients with some parasitic infections (but not cancers) demonstrate low levels of TNF in their sera; thus, they do not seem to be tolerized but produce it continuously. TNF can also be produced in macrophage cultures by treatment with LPS, muramyl dipeptide and other substances. Again, it appears almost immediately and synthesis is maintained for about 8-12 hours. Synthesis is dependent upon the continuous presence of LPS. After synthesis stops it cannot be reinitiated by adding more LPS; thus, the macrophages also appear to be tolerized. Macrophage cell lines eventually become sensitive again after cultivation in LPS-free conditions. Synthesis of TNF is inhibited by actinomycin D or cycloheximide, indicating that it is an inducible protein. Its production is also inhibited by glucocorticoids and prostaglandin E2, indicating that these substances play important roles in the regulation of TNF synthesis.

Production of tumor necrosis factor in unprimed mice: mechanism of endotoxin-mediated tumor necrosis.

Tumor necrosis factor (TNF) was detected in the sera of normal mice, unprimed by reticuloendothelial system (RES) stimulators, when such mice were injected with lipopolysaccharide (LPS). Amounts of TNF were approximately 200-fold less than those found in Corynebacterium parvum-primed mice. No TNF activity was detected in the sera of mice not administered LPS. TNF induction in unprimed mice was refractory to repeated administration of endotoxin, thus exhibiting a tolerance phenomenon. TNF produced in unprimed mice eluted similarly to Mycobacterium bovis, strain BCG-primed TNF on Sephacryl S-200 and DEAE Sephacel columns and was neutralized by rabbit antisera raised to partially purified BCG-primed TNF. When BALB/c mice having 7-day old subcutaneous Meth A tumor implants were administered TNF antiserum, endotoxin-induced hemorrhagic necrosis was largely prevented. These findings strongly suggest that endotoxin-induced hemorrhagic necrosis of tumors is mediated through TNF production and action.

Requirement for the continual presence of lipopolysaccharide for production of tumor necrosis factor by thioglycollate-induced peritoneal murine macrophages.

This work demonstrates the need for the continued presence of lipopolysaccharide (LPS) for tumor necrosis factor (TNF) production by thioglycollate-induced peritoneal macrophages. Removal of LPS at any time resulted in the abrupt cessation of further TNF production. The readdition of LPS resulted in further production of TNF but the yield was limited to the amount that would have been produced had the LPS not been removed.

Pharmacokinetics of murine tumor necrosis factor.

The in vivo administration of tumor necrosis factor (TNF) provides a new approach to the immunotherapeutic treatment of tumors. We evaluated the pharmacokinetics of murine tumor necrosis factor in mice as a model for application in the human system. TNF had a clearance of 0.013 ml/min/g and a serum half life of 10.5 minutes. Its volume of distribution was consistent with the extracellular space. This information can provide parameters by which to select optimal modes of treatment for eradication of in vivo neoplasms.

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.

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.

Rat lung macrophage tumor cytotoxin production: impairment by chronic in vivo cigarette smoke exposure.

Macrophages in the presence of bacteria-derived lipopolysaccharide (LPS) stimuli produce a soluble cytotoxin which is toxic to tumor cells. In this study, we examined various parameters of cytotoxin production from pulmonary lavage cells obtained from Fisher 344 cesarean-derived rats. Cultures of macrophages were derived from pulmonary lavage cells and stimulated in vitro with LPS. Cytotoxin production was assayed in vitro using an L-929 cell target assay. Pulmonary lavage preparations contained a relatively pure population of macrophages, and adherence studies revealed that nonadherent lavage cells contributed negligible amounts of cytotoxin, indicating that macrophages were responsible for cytotoxin production. After LPS stimulation, cytotoxin production became maximal within 10 h and thereafter plateaued. Doses of LPS above 0.1 microgram/ml were optimal for production, and in the absence of LPS, no cytotoxin was detected. Because cigarette smoke is the major etiological factor in the development of lung cancers and because smoking is known to profoundly alter the function of alveolar macrophages in humans and experimental animals, subsequent experiments examined the role of chronic cigarette smoke exposure on tumoricidal activity of lung macrophages. Rats were exposed in vivo for 8 wk to either cigarette smoke or air (sham-treated controls). When lavage cells were cultured and stimulated with LPS (1 microgram/ml), 5- to 10-fold less cytotoxin was produced by lavage cells from rats exposed to cigarette smoke. Similarly, using a direct cytotoxicity assay, lung macrophages of smoke-exposed animals also revealed marked impairment in cytotoxicity against L-929 cell targets, and this was noted over a wide range of macrophage:tumor target cell ratios. Another product of macrophages, interferon, was also decreased in rats exposed in vivo to cigarette smoke when compared to sham-treated controls. These results suggest that cigarette smoke exposure may impair pulmonary macrophage-mediated tumor defense mechanisms.

Physical and biological properties of cyclopolymers related to DIVEMA ("pyran copolymer").

A series of copolymers related in structure to the 1:2 alternating cyclocopolymer of divinyl ether and maleic anhydride (DIVEMA) have been shown to possess antitumor properties. The synthesis and structures of these copolymers are discussed, and their effectiveness as antitumor agents is presented. Certain of the copolymers have been prepared in controlled molecular weight ranges using chain transfer agents, and the resultant copolymers finally fractionated via use of solvent-nonsolvent systems. These samples of narrow molecular weight distribution have been evaluated for their antitumor properties and have been found to be quite effective.

Production of a cytotoxin from phorbol myristate acetate-treated human promyelocytes.

Human promyelocytic leukemia cells, when differentiated into macrophages by treatment with phorbol myristate acetate, secrete a cytolytic factor. Enhanced production was achieved when the cultures were treated with bacterial lipopolysaccharide (LPS). Production of the factor was inhibited when cultures were treated with dactinomycin immediately after LPS treatment. Tritirachium alkaline proteinase treatment inactivated the factor, indicating that it has an essential protein moiety. The molecular weight was found to be approximately 40,000 by Sephacryl S-200 gel filtration. The factor was stable at 56 degrees C for 30 minutes, but 80% of the activity was inactivated at 70 degrees C in 30 minutes. The factor was destroyed (96%) by dialysis against 0.01 M HCl (pH 2) for 14 hours. The cytolytic factor had little activity on normal fibroblasts, but it was able to significantly kill transformed cells in vitro.

Comparison of in vitro cell cytotoxic assays for tumor necrosis factor.

Four published in vitro assays which measure cell cytotoxicity were compared utilizing murine tumor necrosis factor. These included determination of residual cell number by crystal violet staining in the presence and absence of actinomycin D, lack of viability as determined by neutral red uptake, and [3H]thymidine release in cytotoxin treated L929 cells. Treatment of cells with actinomycin D followed by crystal violet staining was the most sensitive method measured. However, addition of actinomycin D to the neutral red uptake assay could be shown to be even more sensitive. Additionally, it was shown how actinomycin D dosage, cell seeding density and time of incubation affect TNF titer.

In vitro production of rabbit macrophage tumor cell cytotoxin.

Rabbit pulmonary lavage cells, consisting mostly of macrophages (90-95%), cultured in the presence of LPS, secreted tumor cell cytotoxin that was similar to tumor necrosis serum cytotoxin. A similar cytotoxin was produced by phorbol-ester-pretreated rabbit bone marrow cells and by blood mononuclear cells when cultured in the presence of LPS. All cytotoxins had molecular weights of approximately 48,000 daltons by gel filtration and eluted from DEAE-Sephadex between 0.28 and 0.32 M NaCl. All were stable to 56 degrees C for 60 min, but labile to 70 degrees C for 20 min. B16C3 melanoma cells and mouse embryo fibroblasts were resistant to the cytotoxins. By 3 h in culture, all effector cells secreted detectable cytotoxin levels. Kinetics of cytotoxin production differed for effector cells derived from the different tissues. No additional cytotoxin production could be demonstrated after 30 h in pulmonary lavage or bone marrow cell cultures, despite a change to fresh medium with LPS. Actinomycin D (I microgram/ml) added with LPS inhibited cytotoxin production (greater than 95%) by pulmonary lavage cells. Delaying addition of actinomycin D after LPS treatment demonstrated that messenger RNA production for cytotoxin was completed by 2 to 6 h.

A photometric and plaque assay for macrophage mediated tumor cell cytotoxicity.

Pretreatment of L-929 cells for 2-3 h with 2 micrograms/ml actinomycin D followed by washing rendered them exceedingly sensitive to the direct cytotoxic effects of murine and rabbit macrophages. We exploited the tremendous increase in sensitivity of L-929 cells to effector cell mediated cytotoxicity by demonstrating simple and convenient photometric and plaque assays capable of being completed in 18 h for the quantitation of macrophage mediated tumor cell killing. The plaques demonstrated were generally visible to the unaided eye and were linearly related to the number of effector cells plated indicating that a plaque represented multitarget cytolysis attributed to a single effector cell. Unlike previously described assays, the effector:target ratios demonstrated were extremely low. Using the described techniques, it was estimated that a single macrophage could kill from approximately 10 to 1000 actinomycin D pretreated and washed target cells. In the presence of LPS-activated effector cells, the majority of these targets that stained with eosin Y did so in a cluster pattern, indicating cytotoxicity rather than mere detachment from the monolayer surface.