Doses Of TNF Research Articles

Human lymphotoxin mutein lacks hypotensive activity but has higher in vivo antitumor activity than lymphotoxin or tumor necrosis factor.

A serious drawback of tumor necrosis factor alpha (TNF) as a clinical antitumor agent is that it also has hypotensive activity. To overcome this problem, derivatives of its sister cytokine lymphotoxin (TNF-beta or LT) were prepared. One of them, mutein 2 (Mut2) has a deletion of amino acids 1-7 but contains substituted amino acids, Met-Phe-Pro at positions 8-10 of the mature human LT. This mutein has no hypotensive activity at the maximum dose (10 mg/kg) tested on rats. In contrast, a much lower dose (1 mg/kg) of TNF and LT caused a significant blood pressure drop. In vivo studies revealed that Mut2 was more effective than TNF or LT against MethA (a mouse tumor line) as judged by the therapeutic ratio [calculated as LD50 (dose that kills 50% of the animals)/ED50 (dose that reduces the tumor size by 50%)]. With five other different mouse tumors and two different human tumors, Mut2 was also effective and the effectiveness was comparable or superior to that of TNF or LT. These results suggest the possibility that this derivative may be usable as a clinical antitumor agent without the serious side effects associated with TNF.

Alpha1-Antitrypsin inhibits the lethal response to TNF in mice.

alpha1-Antitrypsin, an acute-phase reactant in many species, protects significantly against the lethality induced by TNF or endotoxin in mice. The protection is optimal with a single dose of at least 300 microg i.p. or 100 microg i.v. given 2 h before a lethal challenge, either with a low dose of TNF in the presence of galactosamine or a higher dose of murine TNF alone. Under optimal conditions, the drop in body temperature, the release of liver transaminases, and the increase in clotting time are also inhibited. alpha1-Antitrypsin does not protect against a lethal dose of platelet-activating factor. It is suggested that the protection is due to reduced release of platelet-activating factor.

TNF-alpha and doxorubicin in hyperthermic perfusion for limb sarcomas

Eighteen patients, subdivided into groups of three, were perfused for 90 min with escalating doses of TNF-alpha (0.5-3.3 mg) and standard doses of doxorubicin (bolus 0.7-1.4 mg/kg) at a tumor temperature of at least 41 degrees C, with the aim to ascertain the maximum tolerable dose (MTD) and the activity of TNF-alpha combined with doxorubicin in hyperthermic antiblastic perfusion (HAP) for patients with limb sarcomas, candidates for amputation. Tumor response was assessed both pathologically and radiologically. Severe systemic toxicity (WHO) was observed in only 2 patients. Locoregional toxicity (Wieberdink's) was grade I in 3 patients, grade II or III in 10 and grade IV in 5. A strict correlation between the TNF dosage and the grade of limb reaction was found, grade IV being retrieved only with TNF dose >1 mg and/or muscular temperature >41.5 degrees C. Tumor necrosis was evaluated in 16 patients: in 11 (68.8%) it scored more than 75% while in 5 it was 25 to 75%. Four cases (25%) had 100% tumor histological necrosis. Limb sparing surgery was feasible in 13 (81%). Our findings suggest that this is a well-tolerated and highly active regimen in HAP.

Transforming growth factor-beta 1 inhibits the production of IL-8 and the transmigration of neutrophils through activated endothelium.

A central mechanism of inflammation is the activation of vascular endothelium by the inflammatory cytokines TNF-alpha and IL-1. These cytokines induce the expression of adhesion molecules, the elaboration of chemokines, and the transendothelial migration of white cells. TGF-beta 1 has anti-inflammatory properties, is expressed in the vessel wall, and has previously been shown to inhibit leukocyte adhesiveness to the endothelium at least in part by inhibiting the expression of E-selectin. We now show that TGF-beta 1 also inhibits the migration of neutrophils through endothelial monolayers activated by TNF-alpha. At a dose of 10 U/ml TNF-alpha, the transmigration of neutrophils was inhibited 42.7 +/- 7.9% (n = 8) by 0.2 ng/ml TGF-beta 1. Furthermore, TGF-beta 1 inhibited, in a time- and dose-dependent fashion, the elaboration of IL-8 by TNF-activated endothelial cells by between 33 and 78% (TNF doses from 100 down to 0.1 U/ml) and the elaboration of mRNA for IL-8 by 69%. TGF-beta 1 treatment did not significantly alter the TNF-induced IL-8 mRNA stability, suggesting that the mechanism of action of TGF-beta 1 is on gene transcription. Neutrophil transmigration through cytokine-activated endothelium involves both IL-8-dependent and IL-8-independent mechanisms. Using an anti-IL-8 Ab, we show that TGF-beta 1 inhibits only the IL-8-dependent pathway, but does not affect the IL-8-independent transendothelial migration mechanism. These and our previous results show that TGF-beta1, achieves its anti-inflammatory properties by inhibiting the expression of at least two genes, E-selectin and IL-8, which are essential in the inflammatory pathway.

Tumor necrosis factor effects on ascites formation in an experimental tumor model.

In humans, treatment of malignant ascites with bolus TNF leads to resolution of the ascites. In an experimental model NMRI nude mice were inoculated intraperitoneally with human NIH-OVCAR3 adenocarcinoma cells, resulting in production of ascites and intraperitoneal tumor growth. Ascites formation and tumor growth after IP injection of recombinant human TNF was determined. Depending on the treatment schedule, a dual effect of TNF on the development of ascites was seen. Doses of TNF (1-10 micrograms/g) given once per week completely prevented ascites production, whereas the same doses of TNF given on a daily schedule induced enhanced ascites formation in an inverse TNF dose relationship. The area of tumor cell-covered peritoneal lining corresponded to these findings, indicating a correlation of tumor mass with ascites production. In an attempt to prevent renewal of ascites after drainage, neither inhibition nor enhancement in ascites production was seen when TNF was given five times per week. However, doses of 10 micrograms/g of TNF once per week led to almost complete inhibition of ascites reappearance. Histological examination of animals that received repeated TNF treatment demonstrated chronic peritonitis with strong stromal proliferation, angiogenesis, and increased adhesion of tumor cells to the peritoneum.

High-dose tumor necrosis factor alpha produces an impairment of hamster diaphragm contractility. Attenuation with a prostaglandin inhibitor.

We have investigated the influence of the cytokine tumor necrosis factor alpha (TNF alpha), an important mediator of sepsis, on in vitro hamster diaphragm contractility. Costal diaphragm strips were excised and mounted on an experimental apparatus consisting of a force transducer and servomotor. Preparations were randomized to incubation in one of the following solutions: (1) indomethacin 10(-6) M (n = 5); (2) TNF alpha (0.1 ng/ml) (n = 5); (3) TNF alpha (500 ng/ml) (n = 5); and (4) TNF alpha (500 ng/ml) plus indomethacin (10(-6)) (n = 5). Baseline contractile parameters measured at optimal length included twitch and tetanic tension, half relaxation time, time to peak tension, force frequency response (10-80 Hz), and fatigability to response to repetitive stimulation. After 90-min incubation in one of the solutions, an identical stimulation protocol was repeated. Initial twitch and tetanus parameters were similar between groups. Maximal twitch tension and tetanic tension decreased significantly, as did tetanic stimulations at 10-80 Hz in the TNF group (500 ng/ml) (p < 0.05). Coincubation with indomethacin decreased but did not completely abolish changes in diaphragm function caused by the higher dose of TNF. There were no significant changes in twitch or tetanus parameters, or in response to repetitive stimulation after incubation in the lower dose TNF group (0.1 ng/ml). We conclude that TNF causes impairment of in vitro diaphragm contractility at high incubation concentrations of TNF and that this effect can be partially blocked by prostaglandin synthetase inhibition. No significant deleterious effect on in vitro contractility was detected at concentrations of TNF similar to serum levels in human sepsis.

Effects of tumor necrosis factor alpha on skeletal muscle amino acid metabolism studied in-vivo.

The present study was performed to determine the chronology of the effects of a single 50 ug subcutaneous dose of TNF on food intake, weight gain, and skeletal muscle protein metabolism in normal rats. Earlier work demonstrated that a single subcutaneous dose of 50 ug of tumor necrosis factor alpha (TNF) significantly increased skeletal muscle protein synthesis and breakdown in the tumor bearing rat [1]. Some of the earlier work demonstrated that TNF can reduce food intake, weight gain and enhance muscle catabolism. Twenty-five male Sprague Dawley rats were randomized assigned to treatment or saline arms of the study. Rates of in vivo incorporation of L-1-14C-leucine into skeletal muscle were measured by the flooding dose technique. Rats were studied 6 and 60 hours after TNF or saline. Six hours after administration of the TNF, the total skeletal muscle amino acid concentration was significantly reduced by 20%. The greatest reductions were seen in lysine, arginine, and isoleucine (39-53%) followed by serine, tyrosine, ornithine, threonine and alanine (18-32%). Despite this drop in skeletal muscle amino acid concentrations, the rate of skeletal muscle protein synthesis was similar to the controls (12.2 +/- 4.1 vs 13.8 +/- 3.7 %/day, mean +/- sd, saline vs TNF treated, respectively). Dietary intake (8.2 +/- 0.5 vs 7.3 +/- 1.1 g/day) and weight gain (7.1 +/- 1.1 vs 9.1 +/- 3.8 g/day) were not affected by TNF administration. However, there was a significant increase in skeletal muscle protein synthesis rate in the TNF treated group after 60 hours (17.8 +/- 4.0 vs 12.2 +/- 4.1 %/day) but not after 6 hours (13.8 +/- 3.7 vs 13.7 +/- 3.3 %/day) compared to saline treated rats, respectively. TNF administration after 60 hours was not associated with an elevated skeletal muscle 3-methyl-histidine concentration or a reduced nitrogen balance. These data suggest that at a 50 ug subcutaneous dose of TNF, an early (6 hours) effect is to reduce skeletal muscle of amino acids without effecting either synthesis or breakdown. A later effect (60 hours) is to normalize skeletal muscle amino acid concentration and to increase skeletal muscle protein synthesis. This suggests that TNF may acutely alter amino acid transport as one of its modes of action.

Contribution of TNF and of LPS in endotoxemic shock in mice. A reappraisal

Species of mice have a different sensitivity to LPS. The mechanisms underlying these differences are not clear. We have investigated the contribution of TNF and of LPS in inducing lethality in endotoxemic models using LPSsensitive C57BI/6 and Balb/c mice, OF1 mice with an intermediate sensitivity, and LPS-resistant C3H/HeJ mice. Our observations showed that TNF largely contributed to lethality, since anti-TNF antibodies protected sensitive Balb/c mice from death over a large range of LPS concentrations. OF1 mice were relatively insensitive to LPS and this was associated with a lesser production of TNF. Similarly, OF1 mice had a reduced sensitivity to challenge with recombinant TNF than Balb/c mice. These observations, therefore, indicated that TNF production and sensitivity were determinant for outcome upon LPS challenge. LPS levels were similar in Balb/c, C57BI/6, and OF1 mice, suggesting that a difference in LPS clearance did not contribute to the differences in sensitivity to LPS. The contribution of the combination of both TNF and LPS in endotoxemic shock was investigated with the LPS-resistant C3H/HeJ mice. While these mice were resistant to challenge with either LPS or a low dose of TNF, combination of non lethal concentrations of LPS and TNF induced death. These data, thus, suggest that while TNF is critical for mediating LPS-induced death, the combination of both LPS and TNF act synergistically in contributing to death, particularly in animal species with reduced sensitivity to LPS.

TGF-beta and endothelial cells inhibit VCAM-1 expression on human vascular smooth muscle cells.

Vascular smooth muscle cells (VSMCs) are normally devoid of the adhesion protein vascular cell adhesion molecule-1 (VCAM-1), which has, however, been observed on human VSMCs in atheroma. We now show that cultured human saphenous vein VSMCs express small amounts of VCAM-1 and that the cytokine tumor necrosis factor-alpha (TNF-alpha) induces, in a time- and dose-dependent fashion, a significant increase in its expression. Interleukin (IL)-4, IL-1, and to a lesser extent interferon gamma have similar effects. TNF-alpha-stimulated human VSMCs demonstrate increased binding of T lymphocytes that is totally VCAM-1 mediated. The cytokine transforming growth factor-beta (TGF-beta) at 2.0 ng/mL inhibited basal VCAM-1 expression by 84 +/- 8% and the induction by TNF-alpha by between 56 +/- 16% and 77 +/- 15% depending on the dose of TNF. Furthermore, coculture on opposing sides of a polycarbonate filter of human VSMCs with human umbilical vein endothelial cells also inhibited the induction of VCAM-1 by 47 +/- 6%. As active TGF-beta is produced upon the coculture of VSMCs and endothelial cells, we suggest that the close physical proximity of these cells in vivo is responsible for the lack of expression of VCAM-1 on VSMCs and that the interruption of this contact in atheroma is an important pathogenic event. As VCAM-1 not only serves as an adhesion molecule but also as a costimulator of immune cells, its expression may be crucial in the propagation of vascular lesions.

Temporal effects of tumor necrosis factor-α on intracellular survival of Mycobacterium paratuberculosis

The causative agent in Johne's disease is Mycobacterium paratuberculosis, an intracellular pathogen which causes enteritis in ruminants. Little is known about interactions between the host cell (macrophage) and M. paratuberculosis; however, this bacterium is able to evade normal host immune defenses and cause a chronic infective state. In the present study, we evaluated whether activation of a murine macrophage cell line (J774.16) by pretreatment with recombinant murine tumor necrosis factor alpha (TNF) prior to infection with M. paratuberculosis would affect their ability to restrict growth and kill the ingested bacteria. A murine cell line was utilized owing to difficulty in obtaining bovine reagents and lack of a continuous bovine macrophage cell line for repeated experimentation. After 4 h of infection, numbers of viable bacteria in cell lysates were significantly lower for macrophages pretreated with 1000 IU TNF ml −1. The rate of bacterial growth as assessed by BACTEC radiometric culture system was also reduced at this time point. Upon further extension of the infection period to 72 h, we observed that moderate doses of TNF (10–1000 IU ml −1) significantly increased the number of viable M. paratuberculosis recovered whereas the highest dose of TNF (4000 IU ml −1) effectively reduced bacterial numbers. These data indicate that TNF can either enhance or reduce macrophage mycobactericidal and mycobacteriostatic activity depending upon both the level of TNF to which cells are exposed and the duration of infection.

Cytotoxic interactions of tumor necrosis factor, melphalan and 41.8 °C hyperthermia

Experience with limb perfusion-hyperthermia, TNF, and l-PAM suggests dramatic clinical responses in sarcoma and malignant melanoma. To extrapolate these results to clinical 41.8 °C whole-body hyperthermia (WBH) and systemic therapy, we studied the cytotoxic interactions of TNF, l-PAM and hyperthermia in L929 cells. The optimal sequence was TNF preceding 41.8 °C hyperthermia by 48 h, and l-PAM given simultaneously with heat. Trimodality synergism between TNF, hyperthermia and l-PAM was demonstrated. Non-cytotoxic doses of TNF had a superadditive interaction with l-PAM/heat. Conversely, non-cytotoxic doses of l-PAM had super-additive interactions with TNF followed by hyperthermia. Relative to therapeutic index, we studied WBH, l-PAM and TNF in non-tumor bearing mice. The optimal trimodality sequence did not result in increased normal tissue toxicity compared to l-PAM alone. The concentrations and sequencing of TNF and l-PAM studied are consistent with clinical application to WBH.

Hepatic mitochondrial enzyme activity and serum amino acid composition in rats treated with tumor necrosis factor

The biochemical integrity of hepatocellular mitochondria was investigated in rats treated with small doses of human recombinant tumor necrosis factor-alpha (Hur-TNF;50-100 micrograms/kg/d injected intraperitoneally for 5 d) by measuring the activities of three mitochondrial enzymes, glutamate dehydrogenase, succinate dehydrogenase and malate dehydrogenase. The activity of glutamate dehydrogenase (a mitochondrial matrix enzyme) was 20% to 34% lower than that of control rats (P = 0.02 to 0.0003). The activities of succinate dehydrogenase (an inner mitochondrial membrane enzyme) and malate dehydrogenase (a mitochondrial matrix and cytosolic enzyme) showed no significant difference. The effect of TNF on serum amino acid composition was studied using pair-fed, weight-matched partners to eliminate any effect of the reduction of food intake due to TNF treatment. The results for the TNF-treated rats showed a significant (P < 0.05) increase in the concentration of 12 of the 21 amino acids measured (range = 33% to 140%). Of these, major increases were observed in the urea cycle intermediates, ornithine (140%) and arginine (59%), as well as proline (94%), alanine (41%), valine (61%), leucine (64%), isoleucine (63%), and aspargine (71%). Since previous studies have shown that the treatment of rats with the same low doses of TNF did not cause any change in mitochondrial ultrastructure detectable by electron microscopy, these results suggest that significant biochemical changes in amino acid metabolism occur as a result of a decrease in mitochondrial glutamate dehydrogenase activity.

Inhibitory effect of the human recombinant tumor necrosis factor on the growth of the Morris hepatoma in rats

The effect of the human recombinant tumor necrosis factor alpha (h rec TNF-alpha) on the transplantable Morris hepatoma 5123 was studied in Buffalo rats. The cytokine was repeatedly administered intratumorly (i.t.) in a dose of 1.5 x 10(4) U once a day in a cycle of four and eight days. The control groups consisted of animals given saline i.t. The experiments revealed an inhibitory effect of the h rec TNF-alpha upon the growth of neoplastic tumors. The biometric parameters of the tumors indicated that the inhibition of the Morris hepatoma was most effective after eight repeated doses of TNF. After injections of TNF-alpha, the tumors presented extensive hemorrhagic necrosis, the regressive alterations being found mainly in the central and intermediate tumor zones. In the early phase of the tumor growth, neoplastic tissue necrosis prevailed, as well as hemorrhages within the necrotic masses, necrosis of the blood vessel walls and thrombi in their lumina. In the later period, numerous fibres of the fibrous tissue, richly vascularized, occurred in the peripheral and intermediate zones. Clusters of eosinophilic granulocytes and macrophages with apoptotic bodies in the cytoplasm were seen on the border of the necrotic foci.

In vivo production of exotoxin A and its role in endogenous Pseudomonas aeruginosa septicemia in mice

We have examined the production of Pseudomonas aeruginosa exotoxin A (ETA) and its role in endogenous bacteremia in mice. Mice given P. aeruginosa D4 orally died of bacteremia between days 10 and 13 following cyclophosphamide-induced leukocytopenia. In this model, serum endotoxin was detected beginning on day 7 by the Limulus assay and P. aeruginosa was cultured from blood beginning on day 9. ETA and tumor necrosis factor alpha (TNF) were also detected in serum by enzyme-linked immunosorbent assay beginning on day 9. Purified ETA did not stimulate the production of TNF in normal mice primed with a synthetic derivative of muramyl dipeptide in the absence of endotoxin. However, ETA enhanced and primed endotoxin-induced TNF production in mice. The mortality rate of mice given ETA mutant PAO-PRI (5.0%) was significantly lower than that of mice given the parent strain (78.8%). These data indicate that ETA may be an important factor in the occurrence of P. aeruginosa bacteremia and/or the death of mice. Also, ETA may be responsible for enhancing the production of a lethal dose of TNF in the presence of endotoxin in P. aeruginosa bacteremia.

Coagulation disorders in septic shock.

Abnormalities in coagulation and fibrinolysis are frequently observed in septic shock. The most pronounced clinical manifestation is disseminated intravascular coagulation. Recent studies in human volunteers and animal models have clarified the early dynamics and route of activation of both coagulation and fibrinolytic pathways. In healthy subjects subjected to a low dose of either endotoxin or TNF an imbalance in the procoagulant and the fibrinolytic mechanisms is apparent, resulting in a procoagulant state. Also in patients with septic shock a dynamic process of coagulation and fibrinolysis is ongoing with evidence of impaired fibrinolysis. These abnormalities have prognostic significance; the extent of disturbances of coagulation and fibrinolysis is related to the development of multiple organ failure and death.

Augmentation of monocyte-mediated cytocidal activity by a low dose tumour necrosis factor measured by the kinetic colorimetric microplate assay

This paper describes a simple kinetic colorimetric assay for the quantitation of human peripheral blood monocyte-mediated cytotoxic activity against tumour cells. Isolated effector monocytes were cultured overnight with an increasing number of target cells in 96-well microplates. Cytotoxic activity of monocytes was determined by modified nitroblue tetrazolium (MTT) dye assay using standard ELISA reader offering possible automation. The test was performed with three different effector/target cell ratios using a fixed number of monocytes. This allowed the expression of cytotoxic activity of monocytes in cytotoxic activity units. The assay was found to be a simple method to demonstrate that low doses of TNF (1 U/ml) enhanced monocyte-mediated cytotoxicity.

Chronic intraperitoneal infusion of low doses of tumor necrosis factor α in rats induces a reduction in plasma triglyceride levels

Single and repeated bolus injections of tumor necrosis factor α (TNF) in laboratory animals have been reported to result in hypertriglyceridaemia, suggesting that TNF is a mediator of hypertriglyceridaemia occurring during infection. However, as during infection production of TNF is probably chronically elevated, we determined the effects of continuous infusion of low doses of TNF on plasma levels of triglycerides and cholesterol. Male rats, bearing a venous catheter to allow repeated blood sampling, were intraperitoneally equipped with osmotic minipumps which continuously delivered TNF or saline for 7 days. Infusion of rats with doses of TNF as low as 4.0 and 8.0 μg/24 h resulted in significant decreases in plasma levels of triglycerides as compared with those after saline infusion. Although plasma triglyceride concentrations were persistently lower in TNF than in saline animals throughout the study period, the differences were most prominent during the first days and reached statistical significance at day 1, 3, 4 and 5 and of the 4.0 μg experiment and on day 1, 2 and 3 of the 8.0 μg experiment. This suppression of plasma triglyceride concentrations was not accompanied by changes in plasma cholesterol levels. No effects of chronic TNF treatment on food intake, body weight change and rectal temperature of the animals were observed. These findings indicate that chronic infusion of low doses of TNF induces hypotriglyceridaemia in rats. The role of TNF as a factor in mediating hypertriglyceridaemia during infectious diseases needs to be reconsidered.

Effects of tumor necrosis factor, lipopolysaccharide, and IL-4 on the expression of vascular cell adhesion molecule-1 in vivo. Correlation with CD3+ T cell infiltration.

We have injected human TNF, LPS, and IL-4 into the skin of baboons to examine regulation of endothelial leukocyte adhesion molecules (ELAM) in vivo and to determine which endothelial adhesion molecules correlate temporally and spatially with cytokine-induced T cell infiltration. The expression of adhesion molecules ELAM-1 (E-selectin), VCAM-1, and ICAM-1 (CD54) were quantified by immunocytochemical staining of frozen sections obtained from skin biopsies; T cell infiltration was measured by immunocytochemical staining of CD3+ T cells in serial sections. We found that injection of TNF causes late (24 to 48 h) T cell infiltration whereas injection of LPS, in doses that do not cause tissue necrosis, does not. The ability of TNF (but not LPS) to recruit T cells correlates with the ability of TNF to cause sustained endothelial cell adhesion molecule expression. Expression of VCAM-1 on post-capillary venules showed the highest degree of spatial localization with infiltrates. IL-4, although not proinflammatory by itself, can cause T cell infiltration in combination with an ineffective dose of TNF. The ability of IL-4 to augment TNF-induced inflammation best correlates with the ability of the combination of IL-4 and TNF to increase endothelial VCAM-1 expression. In contrast, IL-4 does not promote T cell infiltration or endothelial VCAM-1 expression in combination with LPS. In cytokine-injected tissues, VCAM-1 is also expressed on connective tissue cells other than endothelium, including smooth muscle and perineural cells, where it is induced by cytokines in parallel with endothelial VCAM-1. Overall, our data support the hypothesis that endothelial VCAM-1 expression contributes to T cell extravasation at sites of inflammation. Furthermore, we find that IL-4, a product a Ag-activated T cells, can interact with TNF to selectively promote VCAM-1 expression and the development of T cell-rich infiltrates, characteristic of Ag-induced inflammatory reactions.

The role of TNF in septic ARDS

This study was performed to demonstrate the role of TNF in septic ARDS. The interaction with neutrophil and TNF was examined in both in vitro and in rat experimental observation. The results obtained are as follows: Serum level of natural TNF was significantly increased immediately after the endotoxin injection into the rat vein. In in vitro observation, TNF activated neutrophil and enhanced super oxide production and elastase was released from neutrophil. On the other hand, TNF was inactivated by contact with elastase released from activated PMNs both in dose and in time dependently. Also, in the in vivo study, the serum level of natural TNF that was enhanced by endotoxin injection was continued for a longer period in neutropenic rats than in the normal rat. The lung tissue injury such as cell infiltration, capillary congestion and increased intrapulmonary fluid in morphometric determination were observed only when the extremely high dose of TNF was injected. These findings were more significantly observed in the neutropenic rats than in the normal neutrophil rat. The weaker interaction of PMNs elastase to TNF is suspected in such neutropenic animals. From the above, the role of TNF in septic ARDS may be explained as follows: By endotoxin injection, TNF is released from stimulated macrophages. The released TNF activates neutrophil which plays the main role of septic ARDS. In the usual system, lung tissue damage induced by TNF is inhibited, because TNF is inactivated by elastase released from activated PMNs. However, in neutropenic state, PMNs elastase is not enough to inhibit the TNF action, then the tissue damage is directly induced by TNF. As my conclusion, the role of TNF in septic ARDS is to provide two different ways by the host is condition. One is to activate neutrophils in the usual condition and the another is to introduce direct damage of lung tissue in the neutropenic state.

Concomitant treatment of MBT-2 bladder tumour by tumour necrosis factor alpha and interferon alpha in conjunction with delayed type hypersensitivity immunotherapy

In our previous study [9], we reported the anti-tumour effect of TNF on mouse bladder tumour (MBT-2) both in vivo and in vitro. Inoculation of a single dose of TNF alone caused significant but transient tumour growth inhibition. Subsequent repeated doses of TNF did not sustain or augment the anti-tumour effect. The current experiments were undertaken to assess the anti-tumour activity of (i)-concomitant treatment of TNF-A and IFN-A against MBT-2 bladder tumour and (ii)-concomitant TNF + IFN-A treatment in conjunction with T-DTH (delayed-type hypersensitivity) immunotherapy. Systemic administration of multiple doses of TNF + IFN-A in vivo caused initial partial tumour regression followed by tumour growth inhibition up to 14 days following treatment. This combined treatment showed an enhanced anti-tumour effect compared to TNF-A treatment alone. Immunotherapy of MBT-2 tumour-bearing mice with T-DTH "immune" effector cells alone did not cause significant tumour growth inhibition. In contrast, concomitant administration of both T-DTH effector cells and TNF + IFN-A in MBT-2 tumour-bearing mice resulted in significant tumour growth inhibition for up to 16 days. The immune effector cells conferring immunotherapy were isolated from the spleens of tumour-immunized, "DTH-primed" animals and were characterized as Lyt 1+2- helper/DTH T cells (CD4+ phenotype). These cells mediate both DTH response to MBT-2 tumour antigens as well as anti-MBT-2 tumour protection. In vitro treatment of the "immune" cells with TNF-A resulted predominantly in the proliferation of Lyt 1+ T cells versus Lyt 2+ cells.(ABSTRACT TRUNCATED AT 250 WORDS)