rhTNF Alpha Research Articles

Inhibition of Glucagon-Signaling and Downstream Actions by Interleukin 1β and Tumor Necrosis Factor α in Cultured Primary Rat Hepatocytes

In cultured rat hepatocytes, glucagon increased the phosphoenolpyruvate carboxykinase (PCK1) mRNA by increasing cellular cAMP concentrations. The proinflammatory cytokines rhIL1beta and rhTNF alpha impaired the increase both in cAMP and PCK1 mRNA. Glucose formation from glycogen stimulated by glucagon was also attenuated by the cytokines, very likely due to the attenuation of the cAMP increase. Treatment of hepatocytes with the phosphodiesterase inhibitor IBMX or the inhibitory G-protein (G i) inactivating compound pertussis toxin did not abolish the inhibition of the glucagon-stimulated increase in cAMP by the cytokines indicating that phosphodiesterase and G i were not involved. The activation of adenylate cyclase by forskolin enhanced cAMP and PCK1 mRNA. Again, rhIL1beta and rhTNF alpha attenuated the increase in PCK1 mRNA, however, not that in cAMP. The stimulation of PCK1 mRNA increase with the nonhydrolyzable cAMP analogue CPT-cAMP was inhibited by rhIL1beta and rhTNF alpha indicating interference independent of changes in cAMP levels. It is concluded that rhIL1beta and rhTNF alpha inhibited glucagon-stimulated signal transduction at the site of cAMP formation. In addition, glucagon-stimulated PCK1 mRNA was attenuated independent of cAMP formation very likely on the transcriptional and/or post-transcriptional level.

Hemodynamic effects of nitric oxide synthase inhibition at steady state and following tumor necrosis factor-alpha-induced myodepression.

Nitric oxide (NO) has been proposed as a common mediator of tumor necrosis factor-alpha (TNF alpha)-induced vasodilation and myocardial dysfunction. Accordingly, we performed an extensive assessment of the influence of NO synthase inhibition on left ventricle (LV) and circulatory performance in conscious dogs at steady state and after establishment of TNF alpha mediated myodepression. Autonomically blocked, chronically instrumented dogs were studied at steady state and 6 h after initiation of a 1-h rhTNF alpha infusion (40 micrograms/kg). Ventricular performance was evaluated using the pressure-volume framework. Dogs were then treated with either NG-nitro-L-arginine methylester (L-NAME, 40 mg/kg bolus) or angiotensin II (250-500 ng/kg). L-NAME, under control conditions or following recombinant human (rh) TNF alpha-induced ventricular dysfunction, produced marked increases in afterload with attendant increases in LV pressure, volume, and prolonged isovolumic relaxation without adversely influencing coronary blood flow. regardless of whether the dogs received rhTNF alpha, L-NAME did not affect the slopes of the end-systolic pressure-volume and stroke-work (SW)-end-diastolic volume (EDV) relations (force-based measure of contractility), whereas the slope of the dP/dtmax-EDV relation, a velocity dependent parameter of LV systolic function, declined. Overall ventricular performance, as seen by the circulation, was reduced by L-NAME in control as well as rhTNF alpha-treated dogs, evidenced by rightward shifts of the SW-EDV and dP/dtmax-EDV relations. Similar findings were observed in the separate cohorts of dogs, at steady state and 6 h after rhTNF alpha, following angiotensin II at matched systolic pressure. Systemic NO synthase inhibition with L-NAME does not acutely reverse rhTNF alpha-induced myocardial dysfunction. The detrimental influence of L-NAME on LV size, relaxation, and velocity-based measures of contractility is likely attributable to its effects on increasing afterload.

Thrombocytopenia and complement activation under recombinant TNF alpha/IFN gamma therapy in man.

Infusions of recombinant human tumor necrosis-alpha plus recombinant human interferon-gamma (rhTNF alpha/rhIFN gamma) were assessed in two patients with Ewing's sarcoma. We analyzed platelet count, coagulation and the terminal complement complex (TCC). During cycles with continuous rhTNF alpha-infusions we found a rapid, marked decrease of platelet count (minus 90% of initial values) and a simultaneous increase of TCC (plus 84% of initial values) at day 4. At days 5-7 a spontaneous increase of platelet count and decrease of TCC were visible. Short-term infusion led to a milder, continuous decrease of platelet counts and to a moderate, progressive increase of TCC at days 5-7. Bleeding occurred only as petechia and mild hemoglobinuria. There was no effect related to the dosage of rhTNF alpha or rhIFN gamma. Relevant differences were seen only in the variable time courses of rhTNF alpha application. Ex vivo analysis of one patient's platelets showed no cytokine-related effect on induced aggregation according to Born. Additionally, we analyzed in vitro effects of the cytokines on platelet count, platelet aggregation, and the assembly of TCC in platelet membranes. No effects were found after incubation of platelet-rich plasma (PRP) with 1000 pg/ml rhTNF alpha and/or 50 pg/ml rhIFN gamma. Fluid-phase and membrane-bound TCC did not change after incubation of PRP with cytokines. A slightly time-dependent increase of TCC without alteration of platelet count and platelet function did not agree with the assumption of a direct injury to platelets. We assume a cytokine-mediated role of the endothelium in platelet loss.

Antitumor activity of recombinant human tumor necrosis factor-alpha (rH-TNF alpha) and liposome-entrapped rH-TNF alpha.

The antitumor activities of recombinant human tumor necrosis factor-alpha (rH-TNF alpha) and liposome-entrapped rH-TNF alpha were evaluated in various glioma cell lines and a rat brain T9 gliosarcoma model. rH-TNF alpha had a direct cytotoxic activity against various glioma cell lines in vitro, and indirect cytotoxic activity against gliosarcoma (T9) in vivo. Liposome-entrapped rH-TNF alpha had increased direct cytotoxic activity in vitro, and against experimentally induced brain tumors in vivo. The effects in vivo were probably due to vascular damage of the tumor vessels as shown by histological examination and activation of cytotoxic macrophages as shown in vitro. These results indicate that the general or local administration of liposome-entrapped rH-TNF alpha may become a useful adjunct treatment for malignant brain tumor.

Infiltration of neutrophils by intrapleural injection of tumour necrosis factor, interleukin‐1, and interleukin‐8 in rats, and its modification by actinomycin D

1. To assess in vivo chemotactic activity of tumour necrosis factor (TNF), interleukin-1 (IL-1), IL-8, and cytokine-induced neutrophil chemoattractant (CINC), we injected these cytokines into the pleural cavity of rats. 2. CINC (0.1-1 microgram) and recombinant human IL-8 (rhIL-8, 0.2-5 micrograms) caused neutrophil infiltration into the rat pleural cavity in a dose-dependent fashion, peaking at 3 h. The number of leukocytes in the peripheral blood did not change significantly. 3. RhTNF alpha and rhIL-1 alpha also induced neutrophil accumulation. The dose response curves of rhTNF alpha (0.67 ng-6.7 micrograms) and rhIL-1 alpha (0.45 ng-4.5 micrograms) at 3 h were bell shaped. On the other hand, unlike CINC and rhIL-8, rhTNF alpha and rhIL-1 alpha caused transient marked leukopenia at 3 h in a simple dose-dependent fashion. 4. Concomitant injection of actinomycin D dose-dependently and completely at 10 micrograms inhibited neutrophil infiltration induced by rhTNF alpha (0.67 microgram) and rhIL-1 alpha (0.45 microgram) at 3 h. However, that induced by CINC or rhIL-8 was not affected by actinomycin D. 5. Peaking at 1 h, CINC production in the pleural cavity was found after intrapleural injection of rhTNF alpha (0.67 microgram) or rhIL-1 alpha (0.45 microgram), but not after that of rhIL-8 (5 micrograms). The CINC production induced by rhTNF alpha or rhIL-1 alpha and the neutrophil infiltration was suppressed by concomitant injection of actinomycin D (1 and 10 micrograms). 6. These results indicate that CINC and IL-8 themselves are direct chemoattractants for neutrophils, whereas TNF and IL-1 induce neutrophil infiltration indirectly via newly synthesized mRNA for chemotactic protein including CINC, which may be involved in neutrophil emigration at local inflammatory sites in rats.

Activation of NADPH-Oxidase and Its Associated Whole-cell H+ Current in Human Neutrophils by Recombinant Human Tumor Necrosis Factor α and Formyl-Methionyl-Leucyl-Phenylalanine

Proton accumulation and efflux associated specifically with NADPH oxidation in neutrophils remains to be elucidated. Using confocal fluorescence and patch-clamp recordings from single human neutrophils, in the presence of protein kinase C inhibitors, we studied the transient cytosolic acidification and whole-cell H+ current induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP) and recombinant human tumor necrosis factor alpha (rhTNF alpha). Intracellular pH changes were monitored utilizing the ratiometric imaging of the dual emission fluoroprobe, carboxyseminaphthorhodafluor-1, AM acetate. Bath application of 1000 units/ml rhTNF alpha or 0.1 microM fMLP changed the fluorescence of fluoroprobe-loaded cells, indicating generation of cytosolic H+ ions. In the absence of Ca2+ in the pipette solution, exposure of cells to rhTNF alpha or fMLP for 10 s activated voltage-dependent H+ currents. From tail current analysis, the threshold voltage for H+ current activation was approximately -50 mV. These fMLP- or rhTNF alpha-activated voltage-dependent H+ currents were augmented further in the presence of 0.1 mM of NADPH in the pipette solution, and they were inhibited by bath application of 50 microM of apocynin, an NADPH oxidase inhibitor. These results indicate that rhTNF alpha- or fMLP-induced NADPH oxidase in human neutrophils gives rise to the activation of voltage-dependent H+ currents.

Thermal enhancement of both tumour necrosis factor alpha-induced systemic toxicity and tumour cure in rats

In vitro and in vivo studies have suggested synergistic anti-tumour activity of combined hyperthermia and tumour necrosis factor alpha (TNF-alpha). However, some studies indicated an increased systemic toxicity of TNF by additional hyperthermia. The aim of this study was to obtain starting dosages for a clinical phase I study on the application of deep local hyperthermia and systemic TNF. We investigated the effect of local hyperthermia on the toxicity and efficacy of systemic TNF. Rats (Wag/Rij) carrying a subcutaneously transplanted osteosarcoma in the hind leg received a single intravenous dose of recombinant human (rh) TNF-alpha, either at normothermia or at hyperthermia, by positioning the tumour bearing hind leg in a water bath of 43 degrees C. Dose-effect curves for lethality and tumour cure were established and LD50 and TCD50 values were calculated. Systemic toxicity was increased by local hyperthermia. The LD50 values (+/- s.e.) were 1088 (+/- 61) micrograms kg-1 at normothermia and 205 (+/- 23) micrograms kg-1 at hyperthermia, resulting in a thermal enhancement ratio (TER) of 5.3. Following normothermia, tumour cures were observed at TNF concentrations of 1000-1300 micrograms kg-1, while this was observed at doses of 50-300 micrograms kg-1 when combined with hyperthermia (TCD50 values of 1211 and 188 micrograms kg-1 respectively), resulting in a TER of 6.4. Systemic toxicity and anti-tumour activity of TNF are both increased by local hyperthermia. A safe starting dose for the combined clinical treatment would be 10% of the dose of TNF-alpha that has been recommended for phase II studies on intravenous bolus administration of TNF-alpha at normothermia. In view of the large variability in tumour sensitivity for TNF-alpha, the clinical usefulness of this combined treatment modality has to be determined.

Cytostatic activity of alveolar macrophages from smokers and nonsmokers: role of interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha.

Several functions of alveolar macrophages (AM) are modified by cigarette smoking. AM are the first line of defense in bronchoalveolar spaces and could be depressed in their cytotoxicity to tumor cells in smokers. An assay using A549 cells (human lung adenocarcinoma) as target cells was performed to assess cytostasis mediated by AM and their supernatants (SN) from healthy smokers (n = 8) and nonsmokers (n = 6). Contact-mediated cytostasis was decreased in AM of smokers (n = 8) relative to nonsmokers (n = 6) (22.9 +/- 5.7% versus 42.7 +/- 6.0% [+/- SEM], P < 0.04) and increased after lipopolysaccharide (LPS) stimulation in both groups (34.5 +/- 5.3% versus 46.8 +/- 5.2%, NS). Cytostasis induced by SN from nonstimulated AM was low in both groups and was still lower in smokers after LPS exposure (19.3 +/- 4.5% versus 34.5 +/- 4.8%, P < 0.04). Among cytotoxic factors produced by macrophages, interleukin (IL)-1 beta, IL-6, and tumor necrosis factor alpha (TNF alpha) may play an important role in cytostasis. Recombinant human (rH) IL-1 beta and rHTNF alpha had a moderate cytostatic activity, which was additive, whereas rHIL-6 had no significant activity on A549 cells. Bioactive IL-1 beta, IL-6, and TNF alpha were therefore measured in macrophage SN. Their levels tended to be lower in smokers than in nonsmokers and were much increased after LPS stimulation. Levels of the three cytokines were also found to correlate with each other; furthermore, a good correlation between cytokine levels in SN and cytostasis was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis factor alpha (TNF alpha) downregulates c-kit proto- oncogene product expression in normal and acute myeloid leukemia CD34+ cells via p55 TNF alpha receptors

Tumor necrosis factor alpha (TNF alpha), as a modulator of hematopoiesis, interacts with many growth factor receptors, such as interleukin-3, granulocyte-macrophage colony-stimulating factor (CSF), and granulocyte-CSF receptors. Here, we studied the interactions between TNF alpha and the stem cell factor (SCF) receptor, c-kit, in normal CD34+ hematopoietic progenitors and their leukemic counterpart, ie, acute myeloid leukemic (AML) CD34+ cells coexpressing c-kit antigen. The results showed that (1) incubation of normal bone marrow mononuclear cells with 200 U/mL rhTNF alpha for 20 hours induced a diminution of 31.2% +/- 5.2% of CD34+ cells coexpressing c-kit; (2) the same decrease was observed using purified CD34+ cells and, furthermore, their proliferative response to SCF was inhibited by 31.5% +/- 7.3% after exposure to TNF alpha; (3) similar experiments performed on CD34+ c-kit+ AML cells from 11 patients gave comparable results. Further analysis at the mRNA level indicated that TNF alpha decreased c-kit mRNA transcripts. Moreover, using monoclonal antibodies against the two types of TNF alpha receptors, p75 and p55, we showed that the downregulation of c-kit proto-oncogene product by TNF alpha, on normal and leukemic CD34+ cells, was exclusively mediated by the TNF alpha p55 receptor. Therefore, we conclude that TNF alpha acts as a downregulator of the SCF receptor expression.

Tumor Necrosis Factor α (TNFα) Downregulates c-kit Proto-Oncogene Product Expression in Normal and Acute Myeloid Leukemia CD34+ Cells Via p55 TNFα Receptors

Tumor necrosis factor alpha (TNF alpha), as a modulator of hematopoiesis, interacts with many growth factor receptors, such as interleukin-3, granulocyte-macrophage colony-stimulating factor (CSF), and granulocyte-CSF receptors. Here, we studied the interactions between TNF alpha and the stem cell factor (SCF) receptor, c-kit, in normal CD34+ hematopoietic progenitors and their leukemic counterpart, ie, acute myeloid leukemic (AML) CD34+ cells coexpressing c-kit antigen. The results showed that (1) incubation of normal bone marrow mononuclear cells with 200 U/mL rhTNF alpha for 20 hours induced a diminution of 31.2% +/- 5.2% of CD34+ cells coexpressing c-kit; (2) the same decrease was observed using purified CD34+ cells and, furthermore, their proliferative response to SCF was inhibited by 31.5% +/- 7.3% after exposure to TNF alpha; (3) similar experiments performed on CD34+ c-kit+ AML cells from 11 patients gave comparable results. Further analysis at the mRNA level indicated that TNF alpha decreased c-kit mRNA transcripts. Moreover, using monoclonal antibodies against the two types of TNF alpha receptors, p75 and p55, we showed that the downregulation of c-kit proto-oncogene product by TNF alpha, on normal and leukemic CD34+ cells, was exclusively mediated by the TNF alpha p55 receptor. Therefore, we conclude that TNF alpha acts as a downregulator of the SCF receptor expression.

Activation of autoreactive T-lymphocytes by cultured syngeneic glomerular mesangial cells

The capacity of intrinsic, glomerular mesangial cells (MC) to cause an autoreactive response of syngeneic lymphocytes in vitro are presented. Initial experiments demonstrated the MHC class II dependent capacity of MC to present exogenous antigen to sensitized lymph node lymphocytes (LN) and to activate naive, allogeneic LN in the absence of a nominal antigen. However, the most striking finding of the present investigation was that mouse MC (C57BL/6 or DBA/2) augmented a significant activation of naive, syngeneic lymphocytes. The extent of the proliferative lymphocyte response was comparable to that observed after stimulation with allogeneic MC. Moreover, during syngeneic coculture substantial amounts of interferon bioactivity were generated. Equipotent concentrations of rm IFN-gamma were sufficient to induce class II MHC expression of mouse MC. In control experiments the macrophage cell line, IC-21 (C57BL/6), or freshly prepared DBA/2 mouse peritoneal macrophages did not elicit a syngeneic LN response. Using MC, which had not been pretreated, the MC-specific LN stimulation occurred after prolonged periods of coculture. The stimulation index (S.I.) was 9.77 after 144 hours compared with LN controls (S.I. = 1). However, a 48 hour pretreatment of MC with either rm IFN-gamma alone or in combination with rh TNF-alpha and/or the continuous presence of rm IL-1 alpha during coculture periods from 72 to 144 hours substantially enhanced the proliferative LN response. Analysis of non-adherent LN by flow cytometry (FACS) after 96 or 120 hours coculture with MC revealed an increased ratio of Thy1.2+ to B220+ cells with a predominant rise of L3T4+ T-helper cells compared to Lyt2+ cytotoxic T-cells. Furthermore, immune fluorescence microscopy showed that a fraction of Thy1.2+ lymphoblasts adhered to MC. FACS analysis of these adherent LN after detachment demonstrated that in comparison to cocultures with untreated MC, cocultures of LN with IFN-gamma/TNF-alpha pre-treated MC resulted in a 24.4% increase of Thy1.2+ cells, with 89% of these being L3T4+ T-helper lymphocytes. In conclusion, autoreactivity of preferentially T-helper cells to cocultured glomerular MC was shown, which may represent a useful model of T-lymphocyte dependent glomerulonephritis.

Experimental treatment of equine sarcoid using a xanthate compound and recombinant human tumour necrosis factor alpha.

A xanthate compound with antiviral and antitumoural activities, tricyclodecan-9-yl-xanthogenate (D609) in combination with the potassium salt of the lauric acid (KC12) and, in a further investigation, the above-mentioned substances together with recombinant human TNF alpha (rh-TNF alpha), were tested on equine sarcoid tumours for therapeutic efficacy. A pilot investigation on 5 healthy horses showed that the compounds were well-tolerated; apart from a local, temporary oedema at the injection site, no other clinical symptoms were observed after subcutaneous administration of volumes from 0.1 to 10 ml per injection. The tested concentrations of D609 and KC12 (5 mg/ml solution) and of rh-TNF alpha (50 micrograms/ml) were used for the treatment experiments. The repeated injections of the compounds to 11 sarcoid affected horses were also well-tolerated, except by one horse. In this case the treatment had to be interrupted after two injections because of severe reaction, i.e. fever and lameness due to oedemas. Five horses (n = 6 sarcoids) were treated by local, subcutaneous injection of D609 and KC12 under the tumour at intervals of 3 weeks. On one periocular sarcoid the compounds were applied as an ointment. After a follow-up period of 18 months, 5 tumours did completely regress and one remained unchanged. The periocular tumour showed a reduction in size. Five horses (n = 9 sarcoids) were then treated with a combination of D609, KC12 and rh-TNF alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon gamma and tumour necrosis factor alpha induce a synergistic antiproliferative response in human Ewing's sarcoma cells in vitro.

Three human cell lines derived from Ewing's sarcoma (RM-82, VH-64, and WE-68) were investigated to establish the influence of recombinant human interferon gamma (rhIFN gamma) and tumour necrosis factor alpha (rhTNF alpha) on cell proliferation and survival and to characterize IFN gamma and TNF alpha receptor expression. Incorporation of [3H]thymidine into cells was inhibited by rhIFN gamma after 24 h of incubation. Half-maximal inhibition was observed with 10-80 U/ml rhIFN gamma. A maximal effect (50%-70% inhibition of cell proliferation) was achieved by treatment of cells with 250 U/ml rhIFN gamma. The influence of rhTNF alpha on proliferation was found to differ among cell lines and varied with the concentration and the duration of exposure of cells to this cytokine. In WE-68 and VH-64 cells [3H]thymidine incorporation was not affected by rhTNF alpha up to 2000 U/ml after 96 h of incubation, whereas in RM-82 cells the incorporation was inhibited by 35% after 48 h of incubation with 100 U/ml rhTNF alpha. However, all cell lines showed a synergistic antiproliferative response to the combination of rhIFN gamma and rhTNF alpha after 24 h of incubation. The human recombinant cytokines interleukin(IL)-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-6 and granulocyte/macrophage-colony-stimulating factor, tested alone and in combination with rhIFN gamma and rhTNF alpha, had no influence on cell proliferation. Binding studies in the cell lines with 125I-rhIFN gamma revealed a dissociation constant (Kd) of 160-306 pM and approximately 8000-13,500 receptors/cell. Binding experiments with 125I-rhTNF alpha indicated 430-1250 receptors/cell with Kd ranging from 13 pM to 162 pM. These data indicate that, among various cytokines, only IFN and TNF alpha are capable of potently reducing Ewing's sarcoma cell growth in vitro. Our data suggest that IFN alone or in combination with TNF alpha may be useful in the design of novel strategies in Ewing's sarcoma therapy.

The 55-kD tumor necrosis factor receptor on human keratinocytes is regulated by tumor necrosis factor-alpha and by ultraviolet B radiation.

In previous studies we showed that cultured human keratinocytes expressed the 55-kD TNF receptor (TNFR) and that its expression the important for TNF alpha-mediated upregulation of intercellular adhesion molecule-1 (ICAM-1) expression on keratinocytes. Because factors that either reduce or enhance TNFR expression are likely to have a major impact on the biological effects of TNF alpha on keratinocytes, these studies were conducted to determine the factors that regulate its expression on keratinocytes. Using reverse transcriptase polymerase chain reaction, human keratinocytes were shown to lack 75-kD TNFR expression, indicating that TNF responsiveness of human keratinocytes critically depended on regulation of 55-kD TNFR expression. Human keratinocyte 55-kD TNFR surface and mRNA expression was found to be regulated in vitro by recombinant human (rh) TNF alpha. Stimulation of keratinocytes with rhTNF alpha initially decreased, but later increased, 55-kD TNFR surface expression. This biphasic modulation of 55-kD TNFR surface expression was associated with concomitant changes in 55-kD TNFR mRNA expression. Ultraviolet B (UVB) radiation, a well-known inducer of synthesis and secretion of TNF alpha by human keratinocytes, was found to mimic TNF alpha-induced modulation of 55-kD TNFR surface and mRNA expression via a TNF alpha-mediated autocrine regulatory mechanism. Production of soluble 55-kD TNFR by human keratinocytes remained unaffected by TNF alpha stimulation or UVB irradiation. These studies provide clear evidence that membrane expression of the human 55-kD TNFR may be regulated in human keratinocytes by the ligand itself: TNF alpha. Since in previous studies UVB irradiation transiently inhibited TNF alpha-induced human keratinocyte ICAM-1 expression, it is proposed that UVB radiation-induced biphasic modulation of human keratinocyte 55-kD TNFR expression may affect the capacity of these cells to respond to TNF alpha.

Tumor‐necrosis factor can enhance radio‐antibody uptake in human colon carcinoma xenografts by increasing vascular permeability

Marked differences in the tumor uptake of a 125I-labeled monoclonal antibody (MAb) directed against carcinoembryonic antigen (CEA) were observed in 4 serially transplanted human colorectal carcinomas in nude mice. A comparative study showed that elevated values of measurable tumor vascular parameters, such as permeability, blood flow and blood volume, correlated better with high MAb tumor uptake than the concentration of target antigen in the tumor. In an attempt to modify the vascular parameters and to determine if this could increase antibody uptake by the tumor, rhTNF alpha (TNF) was injected i.t. or i.v. and antibody localization experiments were performed immediately thereafter. Results showed that the permeability of the tumor vessels increased 8 to 10 fold 1 hr after i.t. injection of TNF as compared to control tumors injected with saline. Tumor uptake of 125I-labeled anti-CEA MAb, was 3 times higher 2 hr after i.v. injection and still 27% higher 22 hr later, as compared to results from controls. Intravenous injection of TNF simultaneously with the 125I-labeled anti-CEA MAb also resulted in a 2-fold increase in tumor uptake 4 hr after injection, but the increase was no longer significant 24 hr after injection. Interestingly after i.v. injection of TNF, the MAb concentration in the blood and other normal tissues, such as liver, kidneys, lungs and heart was decreased, resulting in significantly higher ratios of tumor to normal tissue. Taken together the results demonstrate that injection of TNF can increase tumor vascular permeability and improve radio-antibody uptake. This raises the possibility of increasing the radiation dose delivered by antibody to the tumor in the course of radioimmunotherapy.

Recombinant human tumor necrosis factor alpha induces calcium oscillation and calcium-activated chloride current in human neutrophils. The role of calcium/calmodulin-dependent protein kinase.

The role of calcium in the action of tumor necrosis factor (TNF) on human neutrophils is not clear. With fluorescent cytometry, using the visible wavelength calcium probe, fluo-3, and patch clamping, we investigated whether TNF induces cytosolic free Ca2+ changes and Ca(2+)-activated Cl- current, respectively. Bath application of 1000 units/ml recombinant human TNF alpha (rhTNF alpha) induced a rise in cytosolic free Ca2+ in 75% of fluo-3-loaded cells, 25% of which displayed irregular patterns of oscillation. Addition of rhTNF alpha activated Cl- current in 80% of tested cells; the activated current was blocked by 10 microM 5-nitro-2-3-phenylpropylamino)benzoic acid, a Cl- channel blocker. The current was similarly activated by 1 microM ionomycin, a Ca2+ ionophore. To study the mechanism by which rhTNF alpha induced Ca(2+)-activated Cl- current, we examined the involvement of calcium/calmodulin-dependent protein kinase (CaM kinase). With intracellular application of the Ca2+ chelator 1,2-bis (2-aminophenoxy)ethane-N,N,N',N'-tetraacetate (5 mM), the calmodulin antagonist (2 microM), CaM kinase II-(290-309), or the inhibitory peptide (10 microM), CaM kinase II-(273-302), the current was no longer activated by rhTNF alpha. The intracellular application of the control peptide (10 microM), CaM kinase II-(284-302), or the protein kinase C (PKC) inhibitory, PKC-(19-36), or control, [Glu27]PKC-(19-36), peptide (5 microM) did not block the rhTNF alpha-induced Cl- current. These results show that Ca2+ changes are associated with the effects of rhTNF alpha and that CaM kinase plays a role in the mechanism underlying rhTNF alpha-induced activation of Ca(2+)-activated Cl- current in human neutrophils.

Left ventricular systolic and diastolic dysfunction after infusion of tumor necrosis factor-alpha in conscious dogs.

We used a load-insensitive index of systolic left ventricular (LV) function and an analysis of diastolic pressure-dimension relationships to test the hypothesis that recombinant human (rh) tumor necrosis factor-alpha (TNF alpha) impairs LV function in dogs. Animals were studied 7-10 d after aseptic implantation of instrumentation to monitor cardiac output, external anterior-posterior LV diameter, and LV and pleural pressures. Data were analyzed from seven dogs that received active rhTNF alpha (100 micrograms/kg over 60 min) and from five dogs that received heat-inactivated rhTNF alpha. At 24 h after infusion of active rhTNF alpha, the slope of the LV end-diastolic dimension-stroke work relationship decreased significantly, indicating a decrement in LV systolic contractility. Simultaneously, LV unstressed dimension increased significantly, suggesting diastolic myocardial creep. The end-diastolic relationship between LV transmural pressure and normalized LV dimension (strain) was markedly displaced to the left, suggesting increased diastolic elastic stiffness. Despite these changes in LV performance, cardiac index was maintained by tachycardia. The abnormalities in LV function were resolved by 72 h. We conclude that rhTNF alpha reversibly impairs LV systolic and diastolic function in unanesthetized dogs. Because dysfunction occurs greater than 6 h after the infusion of rhTNF alpha and persists for 24-48 h, the mechanism underlying this phenomenon may involve secondary mediators or a change in myocardial gene expression.

A role for tumour necrosis factor‐α in the human mixed lymphocyte culture reaction

The possible role and influence of tumour necrosis factor-alpha (TNF-alpha) in the human mixed lymphocyte culture (MLC) reaction was investigated. Polyclonal rabbit sera to recombinant human-TNF-alpha (rhTNF-alpha) consistently inhibited the MLC, and this could be reversed by simultaneous addition of rhTNF-alpha to the culture medium. Under optimal cell culture conditions, the exogenous addition of 1000 U/mL of rh TNF-alpha had a variable but generally small enhancing effect on the MLC reaction. Additional studies have clearly highlighted the importance of MLC assay conditions in influencing the effect of exogenous rhTNF-alpha. Enhancement of the MLC reaction was only consistently observed under suboptimal cell culture conditions. While the present study clearly supports an important role for TNF in controlling the proliferative response in the human MLC reaction it also highlights the influence of in vitro tissue culture conditions in determining the effect of exogenous TNF-alpha in this assay.

DNA Fragmentation and Cytotoxicity by Recombinant Human Tumor Necrosis Factor in L929 Fibroblast Cells.

Induction of cell DNA fragmentation by treatment of recombinant human Tumor Necrosis Factor alpha (rhTNF alpha) was examined by using mouse L929 cells derived from mouse fibroblast cells. The amount of DNA fragments derived from rhTNF alpha-treated cells, detected by alkaline elution technique, was smaller than that derived from X-irradiated cells. The rhTNF alpha caused the DNA fragmentation depending on its incubation time and concentration. The DNA damage caused by rhTNF alpha treatment correlated with its cytotoxicity. This result suggested that the DNA fragmentation is one of causes of cell death. The treatment with proteinase K of DNA obtained from rhTNF alpha-treated cells did not increase the amount of DNA fragmentation, which indicates that rhTNF alpha causes DNA-fragmentation but not DNA-protein cross-linking.

Two Distinct Effects of Recombinant Human Tumor Necrosis Factor-a on Osteoclast Development and Subsequent Resorption of Mineralized Matrix*

The multifunctional cytokine tumor necrosis factor-alpha (TNF alpha) stimulates osteoclastic resorption. It is not known which steps in osteoclast formation are affected by TNF alpha. We have investigated the effects of recombinant human TNF alpha (rhTNF alpha) on osteoclast development and osteoclastic resorption in two different in vitro resorption systems which are each characterized by a different stage of development of the osteoclast. The effects were further compared to those of bovine PTH-(1-84). rhTNF alpha at concentrations between 0.01-50 ng/ml (3 x 10(-13) to 1.5 x 10(-9) M) did not alter the activity of mature osteoclasts, measured as 45Ca release in fetal mouse radii. In the osteoclast precursor-dependent system (fetal mouse metacarpals) rhTNF alpha had a biphasic effect. It stimulated resorption dose-dependently from 0.01 ng/ml onward, with a maximal response at 0.5 ng/ml. At concentrations above 10 ng/ml rhTNF alpha, resorption was inhibited. In experiments in which irradiation was used to block replication, it was found that TNF alpha stimulates the proliferation of osteoclast progenitors at both low and high concentrations. As a result, at relatively low concentrations, more osteoclasts were formed in the calcified matrix, coinciding with an increased release of 45Ca. However, at relatively high concentrations, the increase in osteoclast progenitors did not lead to increased resorption, since the putative osteoclast progenitors were arrested in the periosteum. In comparison, bovine PTH-(1-84) stimulated resorption independent of proliferation by enhancing the differentiation of postmitotic osteoclast precursors and activating mature osteoclasts. In conclusion, the effects of TNF alpha on osteoclastic resorption are dependent on the stage of osteoclast development and the concentrations applied.