Tumor Necrosis Factor Antagonism Research Articles

Design of Clinical Trials for Mild to Moderate Ulcerative Colitis

Most patients with ulcerative colitis (UC) have mild to moderate disease, for which 5-aminosalicylates (5-ASAs) have remained the mainstay of treatment because of their efficacy, low cost, and excellent safety profile.1–3 However, a substantial proportion of patients fail to maintain remission with 5-ASAs alone and require additional therapy.3 To date, 5 classes of advanced treatments have been approved for the management of moderately to severely active UC: tumor necrosis factor antagonism, integrin antagonism, interleukin-12/23 blockade, Janus kinase inhibition, and sphingosine-1-phosphate receptor modulation.

Granuloma annulare skin profile shows activation of T-helper cell type 1, T-helper cell type 2, and Janus kinase pathways

Granuloma annulare (GA) is an inflammatory skin disorder. Localized GA is often self-resolving, but generalized GA is often recalcitrant to treatments. There are no targeted treatments for GA, largely due to lack of mechanistic understanding. Recently, tumor necrosis factor antagonism showed promise in GA, suggesting an underlying immune pathogenesis. To elucidate the immune pathogenesis and identify potential therapeutic targets for GA. Lesional and nonlesional skin biopsy samples were obtained from patients with GA and evaluated for a large array of inflammatory markers compared with inflammatory markers from normal skin of healthy individuals. We found differential expression of many inflammatory genes compared with normal skin. These genes were associated with T-helper (Th) cell type 1/innate immunity (tumor necrosis factor-α, interleukin [IL]-1β, IL-12/23p40, signal transducer and activator of transcription 1, chemokine [C-X-C motif] ligand 9/10), Janus kinase signaling, and Th2 (IL-4, IL-31, chemokine (C-C motif) ligands 17 and 18; P<.05). Unexpectedly, IL-4 showed significant upregulation in GA lesional skin vs control skin (15,600-fold change). Limited sample size. Our findings shed light on the inflammatory pathways of GA, supporting the notion that immune mechanisms could be driving disease, as suggested by the promising data of tumor necrosis factor-α inhibitors in GA. The significant Janus kinase and particularly Th2 signaling in GA advocates for the investigation of specific Janus kinase- and Th2- targeted drug therapy.

New Approaches in Tumor Necrosis Factor Antagonism for the Treatment of Psoriatic Arthritis: Certolizumab Pegol.

The pathogenesis of psoriatic arthritis (PsA) is still under discussion but great advances have been made in the last 2 decades that confirm the central role of tumor necrosis factor-α (TNF-α) in its inflammatory milieu. New therapeutic approaches have been proposed, and new molecules with anti-TNF-α activity have been chemically altered to improve their pharmacological properties. Certolizumab pegol (CZP) is a PEGylated Fc-free anti-TNF that has been shown clinically to be effective in the treatment of rheumatoid arthritis (RA), skin psoriasis, and PsA. This article summarizes available data on its clinical efficacy and safety profile in the treatment of patients with PsA.

Targeting inflammation in type 2 diabetes by antibody-mediated Tyro-3, Axl, Mer receptor activation.

Multiple mechanisms can cause type 2 diabetes, and the relative contribution of each remains equivocal. Notably, all of these mechanisms are associated with inflammatory response. Some evidence from basic research included islet-derived interleukin-1β (IL-1β) production under hyperglycemia or hyperlipidemia, abundant secretion of tumor necrosis factor (TNF) and monocyte chemoattractant protein 1 (MCP1) by hypertrophy adipocytes, and macrophage infiltration closely linked with insulin resistance1. Furthermore, epidemiological studies have shown elevated circulating levels of C-reactive protein, IL-1β and interleukin-6 (IL-6) in patients with type 2 diabetes. Current medications for type 2 diabetes are insulin, metformin, sulphonylureas, thiazolidinedione, α-glucosidase inhibitors, incretin hormone-based therapy and sodium-dependent glucose cotransporter inhibitors. Those therapeutic targets were mainly focused on hyperglycemia improvement, and adverse effects were still unresolved. Therefore, researchers should not only consider glycemia palliation, but also modulate hyperactivation of the immune system by metabolic stress. The proof-of-concept studies can be briefly categorized into TNF antagonism, inhibitor of nuclear factor-kappa B kinase β/nuclear factor-kappa B inhibition, IL-1 receptor blockade and IL-1β antagonism. Each item will be further discussed respectively.

A Randomized Controlled Trial of the Tumor Necrosis Factor Antagonist Infliximab for Treatment-Resistant Depression

Increased concentrations of inflammatory biomarkers predict antidepressant nonresponse, and inflammatory cytokines can sabotage and circumvent the mechanisms of action of conventional antidepressants. To determine whether inhibition of the inflammatory cytokine tumor necrosis factor (TNF) reduces depressive symptoms in patients with treatment-resistant depression and whether an increase in baseline plasma inflammatory biomarkers, including high-sensitivity C-reactive protein (hs-CRP), TNF, and its soluble receptors, predicts treatment response. Double-blind, placebo-controlled, randomized clinical trial. Outpatient infusion center at Emory University in Atlanta, Georgia. A total of 60 medically stable outpatients with major depression who were either on a consistent antidepressant regimen (n = 37) or medication-free (n = 23) for 4 weeks or more and who were moderately resistant to treatment as determined by the Massachusetts General Hospital Staging method. Three infusions of the TNF antagonist infliximab (5 mg/kg) (n = 30) or placebo (n = 30) at baseline and weeks 2 and 6 of a 12-week trial. The 17-item Hamilton Scale for Depression (HAM-D) scores. No overall difference in change of HAM-D scores between treatment groups across time was found. However, there was a significant interaction between treatment, time, and log baseline hs-CRP concentration (P = .01), with change in HAM-D scores (baseline to week 12) favoring infliximab-treated patients at a baseline hs-CRP concentration greater than 5 mg/L and favoring placebo-treated patients at a baseline hs-CRP concentration of 5 mg/L or less. Exploratory analyses focusing on patients with a baseline hs-CRP concentration greater than 5 mg/L revealed a treatment response (≥50% reduction in HAM-D score at any point during treatment) of 62% (8 of 13 patients) in infliximab-treated patients vs 33% (3 of 9 patients) in placebo-treated patients (P = .19). Baseline concentrations of TNF and its soluble receptors were significantly higher in infliximab-treated responders vs nonresponders (P < .05), and infliximab-treated responders exhibited significantly greater decreases in hs-CRP from baseline to week 12 compared with placebo-treated responders (P < .01). Dropouts and adverse events were limited and did not differ between groups. This proof-of-concept study suggests that TNF antagonism does not have generalized efficacy in treatment-resistant depression but may improve depressive symptoms in patients with high baseline inflammatory biomarkers. clinicaltrials.gov Identifier: NCT00463580.

Synthesis of Vinigrol

The important biological properties, such as platelet aggregation inhibition, antihypertensive activity, and tumor necrosis factor antagonism, coupled with a high degree of structural complexity have rendered vinigrol a target of widespread interest in the synthetic community. Key transformations in the present approach include a highly selective 1,3-dipolar cycloaddition to give tetracycle C, a Saegusa deamination of bromo­isoxazole E and a Shapiro reaction to complete the carbon skeleton.

Systemic sarcoidosis with bone marrow involvement responding to therapy with adalimumab: a case report

IntroductionSarcoidosis is an inflammatory disorder characterized by the presence of non-caseating granulomas in affected organs. The presence of CD4-positive T lymphocytes and macrophages in affected organs suggests an ongoing immune response. Systemic corticosteroids remain the mainstay of treatment, but therapy is often limited by adverse effects. This is the first report of the use of adalimumab (HUMIRA®, Abbott Laboratories, North Chicago, IL, USA), an anti-tumor necrosis factor monoclonal antibody, in a patient with systemic sarcoidosis with bone marrow involvement.Case presentationA 42-year-old African-American man with a medical history significant for hypertension and diabetes mellitus presented with anemia and thrombocytopenia of two months duration. The patient underwent physical examination, bone marrow aspiration and biopsy, chest X-ray, acid-fast bacilli stain, computed tomography with contrast, and additional laboratory tests. He was diagnosed with systemic sarcoidosis with splenomegaly and bone marrow involvement. Drug therapy included prednisone, which had to be discontinued owing to adverse effects, and adalimumab.ConclusionThis is the first report describing the use of adalimumab in a patient with systemic sarcoidosis with bone marrow involvement. Tumor necrosis factor antagonism with adalimumab was efficacious and well-tolerated in this patient and may be considered as a treatment option for similar cases.

Insights into the Structural Basis of the GADD45β-mediated Inactivation of the JNK Kinase, MKK7/JNKK2

NF-kappaB/Rel factors control programmed cell death (PCD), and this control is crucial to oncogenesis, cancer chemoresistance, and antagonism of tumor necrosis factor (TNF) alpha-induced killing. With TNFalpha, NF-kappaB-mediated protection involves suppression of the c-Jun-N-terminal kinase (JNK) cascade, and we have identified Gadd45beta, a member of the Gadd45 family, as a pivotal effector of this activity of NF-kappaB. Inhibition of TNFalpha-induced JNK signaling by Gadd45beta depends on direct targeting of the JNK kinase, MKK7/JNKK2. The mechanism by which Gadd45beta blunts MKK7, however, is unknown. Here we show that Gadd45beta is a structured protein with a predicted four-stranded beta-sheet core, five alpha-helices, and two acidic loops. Association of Gadd45beta with MKK7 involves a network of interactions mediated by its putative helices alpha3 and alpha4 and loops 1 and 2. Whereas alpha3 appears to primarily mediate docking to MKK7, loop 1 and alpha4-loop 2 seemingly afford kinase inactivation by engaging the ATP-binding site and causing conformational changes that impede catalytic function. These data provide a basis for Gadd45beta-mediated blockade of MKK7, and ultimately, TNFalpha-induced PCD. They also have important implications for treatment of widespread diseases.

Vasculoprotective Effects of Anti-Tumor Necrosis Factor-α Treatment in Aging

Vascular aging is associated with dysregulation of tumor necrosis factor (TNF)-alpha expression. TNF-alpha is a master regulator of vascular proatherogenic phenotypic changes, and it has been linked to endothelial dysfunction and apoptosis. To test the hypothesis that anti-TNF-alpha treatment exerts vasculoprotective effects in aging, aged (29 months old) F344 rats were treated with etanercept (1 mg/kg/week for 4 weeks), which binds and inactivates TNF-alpha. In aged carotid arteries, relaxations to acetylcholine were decreased, and endothelial O2* production was increased (as shown by dihydroethidine fluorescence measurements). Etanercept treatment significantly improved responses to acetylcholine and decreased vascular NAD(P)H oxidase activity and expression. In aged carotid and coronary arteries, there were increases in DNA fragmentation rate and caspase 3/7 activity (indicating an increased rate of apoptotic cell death), which were attenuated by etanercept treatment. In aged vessels, there was an up-regulation of inflammatory markers, including inducible nitric-oxide synthase and intercellular adhesion molecule-1, which was decreased by etanercept treatment. In carotid arteries of young animals, recombinant TNF-alpha elicited endothelial dysfunction, oxidative stress, and increased apoptosis and proinflammatory gene expression, mimicking many of the symptoms of vascular aging. Thus, we propose that anti-TNF-alpha treatment exerts anti-aging vasculoprotective effects.

Distal lower extremity paresthesia and foot drop developing during adalimumab therapy

The development of tumor necrosis factor inhibitor biologic therapy is arguably one of the most significant achievements in the treatment of rheumatic diseases to date. Neurologic events suggestive of demyelination have been reported for patients receiving treatment with the antitumor necrosis factor agents etanercept and infliximab. We describe the onset of lower extremity paresthesia and foot drop in a patient who was receiving adalimumab for the treatment of psoriasis and examine the relationship of tumor necrosis factor antagonism and demyelinating disease.

Additive bone‐protective effects of anabolic treatment when used in conjunction with RANKL and tumor necrosis factor inhibition in two rat arthritis models

To investigate whether the bone-preserving effects of a RANKL antagonist or a tumor necrosis factor (TNF) antagonist could be further improved by the addition of a bone anabolic agent in inflammatory arthritis. Lewis rats with either adjuvant-induced arthritis (AIA) or collagen-induced arthritis (CIA) were treated for 10 days with PEGylated soluble tumor necrosis factor receptor type I (PEG sTNFRI), interleukin-1 receptor antagonist (IL-1Ra), osteoprotegerin (OPG), parathyroid hormone (PTH), or combinations of these agents starting on day 4 after disease onset. Treatment effects were assessed clinically, radiologically, and histologically, and by morphometry for the extent of paw swelling, bone erosive changes, and synovial inflammation. Paw swelling and synovial inflammation were significantly inhibited by PEG sTNFRI in AIA and CIA, and by IL-1Ra in CIA. OPG and PTH had no significant effect on these parameters. Analysis of bone erosion revealed a significant bone-sparing effect of monotherapy with PEG sTNFRI or OPG in both models, whereas IL-1Ra was only effective in CIA. PTH treatment alone did not show a bone-protective effect in either model. With the combination of PEG sTNFRI and PTH, erosion scores (-74% in AIA and -61% in CIA versus controls) were significantly lower than those elicited by PEG sTNFRI alone (-41% and -29%, respectively, versus controls). Similar results were also obtained with the combination of OPG and PTH (-88% in AIA and -73% in CIA, compared with -70% and -55%, respectively, with OPG monotherapy). Coadministration of IL-1Ra and PTH had no synergistic bone-sparing effect. Morphometric analysis revealed that the addition of PTH to PEG sTNFRI or OPG resulted in higher bone volume and higher osteoblast numbers in both AIA and CIA. The bone-protective effects resulting from RANKL or TNF antagonism can be further improved by the addition of a bone anabolic agent.

Effect of tumor necrosis factor antagonism on allergen-mediated asthmatic airway inflammation

To assess whether tumor necrosis factor (TNF) antagonism can attenuate eosinophilic airway inflammation in patients with mild-to-moderate allergic asthma. Randomized, double-blind, placebo-controlled trial. National Institutes of Health (NIH) Clinical Center. Twenty-six patients with mild-to-moderate allergic asthma, receiving only inhaled beta-2-agonists, who demonstrated both an early and late phase response to inhalational allergen challenge. Injection of a soluble TNF receptor (TNFR:Fc, etanercept, Enbrel) or placebo, 25mg subcutaneously, twice weekly for 2 weeks, followed by a bronchoscopic segmental allergen challenge. The primary outcome measure was whether TNFR:Fc can access the lung and inhibit TNF bioactivity. Secondary outcome measures included pulmonary eosinophilia, Th2-type cytokines, and airway hyperresponsiveness. Anti-TNF therapy was associated with transient hemiplegia in one patient, which resulted in suspension of the study. Data from the 21 participants who completed the study were analyzed. Following treatment, patients receiving anti-TNF therapy had significantly increased TNFR2 levels in epithelial lining fluid (ELF) (P<0.001), consistent with delivery of TNFR:Fc to the lung. TNF antagonism did not attenuate pulmonary eosinophilia and was associated with an increase in ELF IL-4 levels (P=0.033) at 24h following segmental allergen challenge. TNF antagonism was not associated with a change in airway hyperresponsiveness to methacholine. TNF antagonism may not be effective for preventing allergen-mediated eosinophilic airway inflammation in mild-to-moderate asthmatics. Transient hemiplegia, which may mimic an evolving stroke, may be a potential toxicity of anti-TNF therapy.

Electro-gene therapy of collagen-induced arthritis by using an expression plasmid for the soluble p75 tumor necrosis factor receptor-Fc fusion protein.

Tumor necrosis factor (TNF) is a proinflammatory cytokine involved in the pathogenesis of rheumatoid arthritis, and antagonism of TNF may reduce the activity of the disease. Among a number of techniques for gene transfer in vivo, the direct injection of plasmid DNA into muscle is simple, inexpensive, and safe. In this study, we attempted to treat collagen-induced arthritis (CIA) with anti-TNF gene therapy by transferring the plasmid encoding soluble p75 TNF receptor linked to the Fc portion of human IgG1 (sTNFR:Fc) using in vivo electroporation. DBA/1 mice were immunized with bovine type II collagen and boosted with the same antigen. At 2 days after boosting, the plasmid vector containing cDNA for the sTNFR:Fc was injected into one selected site in the gastrocnemius muscle followed by electroporation. Serum levels of sTNFR:Fc reached 2.3 ng/ml on day 5 when gene expression reached its peak. Macroscopic analysis of paws for redness, swelling and deformities showed that the onset of moderate-to-severe CIA in mice treated with sTNFR:Fc was prevented on a significant level compared with the control mice (P<0.05). The beneficial effect of sTNFR:Fc DNA transfer lasted for at least 18 days following treatment. In addition, both the synovitis and the erosion of cartilage in the knee joints were dramatically reduced in mice treated with sTNFR:Fc (P<0.05). The expression of IL-1beta and IL-12 in the paw was also decreased by sTNFR:Fc treatment (P<0.01) while there was little change in the levels of IL-17 and vWF. These data showed that sTNFR:Fc expression plasmid was effective in the prevention of CIA, and in vivo electroporation-mediated gene transfer may provide a new approach to cytokine therapy in autoimmune arthritis.

Valutazione economica di Infliximab (Remicade®) vs Etanercept (Enbrel®) nel trattamento dell’artrite reumatoide

Rheumatoid arthritis is one of the most severe chronic pathologies, affecting the whole organism, with invalidating outcomes that affect the quality of life of the patients. Its prevalence is estimated to be about 0,5% in Italy, with elevated costs for the national health system (NHS) and the society, in spite of the best treatment with traditional therapies that include anti-inflammatory and disease modifying antirheumatic drugs (DMARDs). The introduction of new drugs with biological activity, mainly acting through an antagonism of tumor necrosis factor (anti-TNF), is a great advance in the management of the disease, as their use has been shown to be effective in slowing the progression of the joint damage, and sometimes in reversing it,. The present article present a cost-minimization study conducted by comparing the two anti-TNFs available in Italy, etanercept and infliximab, assuming equal efficacy and approached from the perspectives of the Italian NHS and society. Only differential costs were considered, i.e. drug acquisition, drug administration and patient monitoring costs, and the analysis comprised two treatment years, in order two account for the cost differences between the first treatment year and the following. The analysis showed that infliximab represents the more convenient alternative from both the NHS and the society points of view, mainly due to lower drug acquisition costs, which offset the higher drug administration costs: the total two year treatment costs per patient with etanercept resulted of 20.173 euro and 22.164 euro from the societal and NHS perspectives, respectively, while the same costs resulted of 13.715 euro and 14.795 euro with infliximab. These results were tested with thorough sensitive analyses, conducted by varying the principal cost and time consumption estimates, that showed that etanercept results less convenient in all the hypothesis tested.

Timing of tumor necrosis factor antagonism is critical in determining outcome in murine lethal acute pancreatitis

Tumor necrosis factor (TNF) is produced in large amounts within the pancreas, lungs, and liver during severe acute pancreatitis and is believed to mediate many of the detrimental consequences typical of this disease. Investigations into the benefit of TNF antagonism have suggested that TNF may also mediate processes that are protective to the host. With the hypothesis that timing plays a role in these dissenting views, TNF was antagonized either prophylactically or therapeutically with a recombinant form of the soluble type I TNF receptor (TNFbp) during a lethal model of necrotizing pancreatitis induced by feeding a choline-deficient diet. Mortality was determined for 10 days in 390 female mice divided into three groups: control, TNFbp early (time, 0 to 5 days), and TNFbp late (time, 1.5 to 5 days). Pancreatitis severity and cytokine production were assessed daily. Animals in the control group had a 75% mortality rate that was significantly decreased by prophylactic TNF blockade (64%, p < 0.05). Delaying TNF antagonism until serum cytokines were elevated and pancreatitis was manifest decreased mortality to 42% (p < 0.001 versus control, p < 0.01 versus early). Early and late TNF blockade decreased pancreatic edema and serum amylase, lipase, interleukin-1, and interleukin-6 (all p < 0.05) but not TNF. Late antagonism typically resulted in the greatest attenuation of all these parameters. Blockade of TNF by the administration of a soluble TNF receptor attenuates the severity of pancreatitis, decreases the production of associated inflammatory cytokines, and significantly improves survival. Delaying antagonism until pancreatitis is manifest and circulating cytokines are elevated but not yet maximal appears to be more protective than simple prophylactic TNF antagonism.

Physiologic Concentrations of TNFα and IL-1β Released from Reperfused Human Intestine Upregulate E-Selectin and ICAM-1

Intestinal ischemia–reperfusion (I/R) causes local and distant tissue injury via neutrophil (PMN) activation and adhesion. Endothelial cell adhesion molecules (E-selectin, ICAM-1) mediate the adhesion and transmigration of PMN in the microcirculation. Expression of these receptors is influenced by cytokines. To determine the physiologic concentrations of two specific cytokines involved in I/R, tumor necrosis factor (TNF) and interleukin-1 (IL-1), human intestinal segments were exposed to 30 min of ischemia followed by reperfusion. Venous effluent samples were obtained; enzyme immunoassays measured maximum concentrations of TNF (30.5 ± 1.0 pg/ml) and IL-1 (59.0 ± 6.0 pg/ml). Cultured human endothelial cells were then exposed to physiologic concentrations of human recombinant TNF (10 pg/ml) and IL-1 (10 pg/ml), individually and in combination. Flow cytometric analysis of receptor expression demonstrated upregulation of E-selectin as early as 2 hr (P< 0.05) with maximum effects at 4 hr. At 4 hr, E-selectin expression (% shift from baseline) was greater with TNF and IL-1 combined (50.9 ± 2.9,P< 0.01) than with either cytokine alone (TNF 34.6 ± 4.0; IL-1 23.5 ± 4.0,P< 0.01). ICAM-1 receptor expression began at 4 hr with maximum effects at 24 hr. ICAM-1 expression after TNF and IL-1 exposure (15.4 ± 1.3,P< 0.001) was also greater than TNF (10.9 ± 0.3,P< 0.01) or IL-1 (3.1 ± 1.5) alone. TNF and IL-1 are present in venous effluent in concentrations capable of increasing PMN adhesion in the microcirculation. These findings support a role for these cytokines in local and distant organ injury from I/R. Since combined effects are greater than either cytokine alone, antagonism of both TNF and IL-1 may be required for a therapeutic benefit in clinical applications.

Effects of antirheumatic agents on cytokines

A review of the literature concerning the effects of traditional antirheumaticdrugs on cytokines and the cytokine and anticytokine approaches already used in the therapy of rheumatoid arthritis (RA) is presented. Many antirheumatic drugs are capable of cytokine modulation in vitro. Corticosteroids inhibit the transcription of a broad spectrum of genes including those encoding monocyte, T cell-derived cytokines and several hemopoietic growth factors, whereas drugs such as cyclosporin A and d -penicillamine interfere with T cell activation more specifically by suppressing i,nterleukin 2 (IL-2) production. The in vivo effects of drug therapy on cytokines in RA patients are less well established. Gold compounds reduce circulating IL-6 levels and the expression of monocyte- derived cytokines, such as IL-1, tumor necrosis factor (TNF), and IL-6, in the rheumatoid synovium. Decreases in circulating IL-6, soluble IL-2 (sIL-2R), and TNF receptors and in synovial fluid IL-1 levels have been reported with methotrexate. Reductions in circulating IL-6 and sIL-2R concentrations have also been observed with cyclosporin and corticosteroids, whereas azathioprine reduces IL-6 but not sIL-2R. Studies on sulfasalazine are conflicting and the in vivo effects of D-penicillamine and antimalarials have not been studied yet. Interferon γ therapy is not effective in RA but may prove a useful antifibrotic for systemic sclerosis. Colony stimulating factors improve the granulocytopenia associated with Felty's syndrome or drug toxicities but can induce arthritis flares and should be reserved to treat infectious complications. Promising results are being obtained with selective antagonism of TNF and IL-1 in RA, and combinations of anticytokine strategies with traditional antirheumatic drugs have been already envisaged. These should preferably be based in a broader knowledge of the effects of antirheumatic agents on the cytokine network.

A tumor necrosis factor (TNF) receptor-IgG heavy chain chimeric protein as a bivalent antagonist of TNF activity.

Using a multistep polymerase chain reaction method, we have produced a construct in which a cDNA sequence encoding the extracellular domain of the human 55-kD tumor necrosis factor (TNF) receptor is attached to a sequence encoding the Fc portion and hinge region of a mouse IgG1 heavy chain through an oligomer encoding a thrombin-sensitive peptide linker. This construct was placed downstream from a cytomegalovirus promoter sequence, and expressed in Chinese hamster ovary cells. A secreted protein, capable of binding TNF and inactivating it, was produced by the transfected cells. Molecular characterization revealed that this soluble version of the TNF receptor was dimeric. Moreover, the protein could be quantitatively cleaved by treatment with thrombin. However, the monovalent extracellular domain prepared in this way has a greatly reduced TNF inhibitory activity compared with that of the bivalent inhibitor. Perhaps because of its high affinity for TNF, the chimeric protein is far more effective as a TNF inhibitor than are neutralizing monoclonal antibodies. This molecule may prove very useful as a reagent for the antagonism and assay of TNF and lymphotoxin from diverse species in health and disease, and as a means of deciphering the exact mechanism through which TNF interacts with the 55-kD receptor.