Infusion Of Monoclonal Antibody Research Articles

Rituximab for the treatment of lupus erythematosus panniculitis

Lupus erythematosus panniculitis (LEP) or lupus profundus (LP) is a clinical variant of lupus eryhematosus that involves the deep dermis and the subcutaneous fat and is associated with tender subcutaneous nodules or plaques, with occasional ulceration, atrophy, and scarring. The management of this entity can be difficult because of the lack of response to conventional treatments, such as systemic steroids and antimalarials. The two patients of this study presented LP refractory to several therapies that demonstrated a remarkable improve to the infusion of the anti-CD20 monoclonal antibody, rituximab at a dosage of 375 mg/m²/week. After the first infusion, painful lesions had resolved without the appearance of new lesions. Rituximab may be an effective treatment for patients with LP when other therapies are ineffective. To date, there is only one case report of LEP treated with rituximab in the literature.

Drug Treatment of Eosinophilic Oesophagitis

Eosinophilic oesophagitis is a clinicopathological disease characterized by oesophageal eosinophilia and gastrointestinal symptoms. Currently, the optimal treatment regimens remain unclear. The pathogenesis of eosinophilic oesophagitis appears to involve immune dysregulation, while acid reflux may have a secondary role; the mainstays in treatment are aimed principally at these dual processes. While a trial of a PPI is worthwhile it is likely that PPI therapy is treating concurrent acid reflux rather than true eosinophilic oesophagitis. Dietary elimination with elemental feed is safe but poorly tolerated. Swallowed topical steroids are the mainstay of commercially available therapies. Both fluticasone and budesonide have been proven to be beneficial both symptomatically and in reducing oesophageal eosinophil counts in the short and medium term. Basic studies have determined a role for IL-5 in oesophageal remodelling in eosinophilic esophagitis. Initial clinical studies have shown single or multiple infusions of monoclonal antibody to IL-5 to be well tolerated and to cause a long-term decrease in both peripheral and sputum eosinophil count in these eosinophil driven conditions. At present, swallowed corticosteroids are the mainstay of treatment for patients with eosinophilic oesophagitis in patients failing PPI therapy. Studies have been heterogenous in their diagnostic criteria for eosinophilic oesophagitis and in the definition of response to therapy, making comparison of results difficult.

Vaccine model of antiphospholipid syndrome induced by tetanus vaccine

Successful induction of antiphospholipid syndrome (APS) in two different non-autoimmune prone mouse strains, BALB/c and C57BL/6, was achieved by tetanus toxoid (TTd) hyperimmunization using different adjuvants (glycerol or aluminium hydroxide), and different adjuvant pretreatments (glycerol or Complete Freund's Adjuvant (CFA)). APS had different manifestations of reproductive pathology in BALB/c and C57BL/6 mice: fetal resorption (as a consequence of extreme T-cell activation obtained in the course of pretreatment), and lowering of fecundity (as a consequence of polyclonal B-cell stimulation), respectively. In BALB/c mice fetal resorption coincided with glycerol and CFA pretreatments, while in C57BL/6 mice lowering of fecundity was most obvious in CFA-pretreated mice immunized with TTd in aluminium hydroxide. Both molecular mimicry and polyclonal B-cell activation occur in APS induction, with molecular mimicry effects being dominant in BALB/c mice, and polyclonal cell activation being dominant in C57BL/6 mice. Confirmation of molecular mimicry effects, which in the condition of T-cell stimulation generated fetal resorptions in the BALB/c strain, was achieved by passive infusion of monoclonal antibody (MoAb) T-26 specific for TTd and anti-β(2)-glycoprotein I obtained after TTd hyperimunization. High polyclonal B-cell activation in C57BL/6 mice prevented fetal resorption but induced fecundity lowering, as was the case in passive administration of MoAb T-26 in this mouse strain. Passive infusion of anti-idiotypic MoAb Y7 into C57BL/6 mice induced fetal resorptions and confirmed the above suggestion on the protective role of polyclonal B-cell stimulation in fetal resorptions.

Phase I trial of a novel human monoclonal antibody mAb216 in patients with relapsed or refractory B-cell acute lymphoblastic leukemia

This phase I trial was conducted to determine the safety and pharmacokinetics of monoclonal antibody 216, a human monoclonal Immunoglobulin M antibody targeting a linear B-cell lactosamine antigen, administered alone and in combination with vincristine in patients with relapsed or refractory B-cell acute lymphoblastic leukemia, and to preliminarily assess tumor targeting and efficacy. Three cohorts of patients received escalating doses of monoclonal antibody 216 administered as an intravenous infusion. In the case of poor response to the first dose of monoclonal antibody 216 alone, defined as less than 75% reduction in peripheral blood blast count, a second dose of the antibody with vincristine was given between days 4 and 7. Responses were assessed weekly until day 35. Serum concentration of monoclonal antibody 216 was measured before and after infusion. Monoclonal antibody 216 targeting was determined with an anti-idiotypic antibody to monoclonal antibody 216 and preliminary efficacy was analyzed by changes in peripheral blood blasts. Thirteen patients were enrolled. One episode of grade 3 epistaxis was the only dose-limiting toxicity observed. All patients showed a poor response to the first monoclonal antibody 216 infusion with a decrease in peripheral blasts from 6-65% in 9 patients. In 8 patients, addition of vincristine to monoclonal antibody 216 resulted in an average reduction of the peripheral blasts of 81%. One patient without peripheral blasts achieved a hypoplastic marrow without evidence of leukemia after one infusion of monoclonal antibody 216 and monoclonal antibody 216/vincristine each. Monoclonal antibody 216 was detected on peripheral blasts in all patients. Treatment with monoclonal antibody 216 in combination with vincristine is feasible and well tolerated in patients with relapsed or refractory B-cell acute lymphoblastic leukemia. Binding of monoclonal antibody 216 to leukemic blasts was efficient, and favorable early responses were observed.

Case of ABO-Incompatible Living Donor Kidney Transplantation without Blood Products in a Jehovah's Witness

ABO-incompatible kidney transplantations have been performed successfully in Korea without splenectomy using plasmapheresis, anti-CD20 monoclonal antibody infusions and other immunosuppressants. However, there is no report of a case of ABO-incompatible kidney transplantation in a Jehovah’s Witness. Hence, we report our experience of successful ABO-incompatible kidney transplantation without blood products in a Jehovah’s Witness. The recipient was treated with six sessions of plasmapheresis and he received intravenous rituximab before transplantation. Immunosuppressive regimen consisted of tacrolimus, mycophenolate mofetil and steroid. The replacement fluid for plasmapheresis was 5% albumin solution instead of fresh frozen plasma. We measured the clotting factors before and after plasmapheresis and used cryoprecipitate to prevent bleeding.

Combination of epitope-optimized DNA vaccination and passive infusion of monoclonal antibody against HER2/neu leads to breast tumor regression in mice

HER2/neu is an oncogene amplified and over-expressed in 20-30% of breast adenocarcinomas. Treatment with the humanized monoclonal antibody trastuzumab has shown efficacy in combination with cytotoxic agents, although resistance occurs over time. Novel approaches are needed to further increase antibody efficacy. In this study, we provide evidence in a mouse breast cancer therapeutic tumor model that the combination of active immunization with a modified HER2/neu DNA vaccine and passive infusion of an anti-HER2/neu monoclonal antibody leads to significant regression of established tumors. Our data indicate that combination therapy with a HER2/neu DNA vaccine and trastuzumab may have clinical activity in breast cancer patients.

Immune modulation with weekly dosing of an agonist CD40 antibody in a phase I study of patients with advanced solid tumors

Background: Single-dose infusion of the agonistic anti-CD40 monoclonal antibody (mAb) CP-870,893 accomplishes immune activation and clinical responses in patients with advanced cancers, but repeat dosing of this agent has not been reported.Patients and methods: Patients with advanced solid tumor malignancies received weekly intravenous infusions of CP-870,893 in four dose level cohorts. Safety and immune pharmacodynamics were assessed.Results: Twenty-seven patients were enrolled. The most common adverse event was transient, infusion-related cytokine release syndrome (CRS). Dose-limiting toxicities included grade 3 CRS and grade 3 urticaria; the maximum tolerated dose (MTD) was estimated to be 0.2 mg/kg. Seven patients (26%) had stable disease as the best clinical response; no partial or complete responses were observed. At the MTD, patient B lymphocytes exhibited persistently increased expression of costimulatory and adhesion molecules without resetting to baseline between doses. In 4 of 8 patients (50%) evaluated at the MTD, there were marked declines in total CD3+ T lymphocytes, as well as CD4+ and CD8+ subsets.Conclusions: Weekly infusions of the agonist CD40 antibody CP-870,893 were well-tolerated, but there was little clinical activity in advanced cancer patients. Correlative studies demonstrate chronic B cell activation and in some patients, T cell depletion. Longer dosing intervals may be desirable for optimal immune pharmacodynamics.

Anti-PrPC monoclonal antibody infusion as a novel treatment for cognitive deficits in an Alzheimer's disease model mouse.

BackgroundAlzheimer's Disease (AD) is the most common of the conformational neurodegenerative disorders characterized by the conversion of a normal biological protein into a β-sheet-rich pathological isoform. In AD the normal soluble Aβ (sAβ) forms oligomers and fibrils which assemble into neuritic plaques. The most toxic form of Aβ is thought to be oligomeric. A recent study reveals the cellular prion protein, PrPC, to be a receptor for Aβ oligomers. Aβ oligomers suppress LTP signal in murine hippocampal slices but activity remains when pretreated with the PrP monoclonal anti-PrP antibody, 6D11. We hypothesized that targeting of PrPC to prevent Aβ oligomer-related cognitive deficits is a potentially novel therapeutic approach. APP/PS1 transgenic mice aged 8 months were intraperitoneally (i.p.) injected with 1 mg 6D11 for 5 days/week for 2 weeks. Two wild-type control groups were given either the same 6D11 injections or vehicle solution. Additional groups of APP/PS1 transgenic mice were given either i.p. injections of vehicle solution or the same dose of mouse IgG over the same period. The mice were then subjected to cognitive behavioral testing using a radial arm maze, over a period of 10 days. At the conclusion of behavioral testing, animals were sacrificed and brain tissue was analyzed biochemically or immunohistochemically for the levels of amyloid plaques, PrPC, synaptophysin, Aβ40/42 and Aβ oligomers.ResultsBehavioral testing showed a marked decrease in errors in 6D11 treated APP/PS1 Tg mice compared with the non-6D11 treated Tg groups (p < 0.0001). 6D11 treated APP/PS1 Tg mice behaved the same as wild-type controls indicating a recovery in cognitive learning, even after this short term 6D11 treatment. Brain tissue analysis from both treated and vehicle treated APP/PS1 groups indicate no significant differences in amyloid plaque burden, Aβ40/42, PrPC or Aβ oligomer levels. 6D11 treated APP/PS1 Tg mice had significantly greater synaptophysin immunoreactivity in the dentate gyrus molecular layer of the hippocampus compared to vehicle treated APP/PS1 Tg mice (p < 0.05).ConclusionsEven short term treatment with monoclonal antibodies such as 6D11 or other compounds which block the binding of Aβ oligomers to PrPC can be used to treat cognitive deficits in aged AD transgenic mice.

Anti-PrPC monoclonal antibody infusion as a novel treatment for Aß oligomer cognitive deficits

Background: Alzheimer’s Disease (AD) is the most common of the conformational neurodegenerative disorders characterized by the conversion of biological protein to the b-sheet-rich pathological Ab isoform. Ab forms toxic oligomers and fibrils which assemble into neuritic plaques. AD pathology also includes the abnormal phosphorylation of tau protein which forms neurofibrillary tangles. A recent study reveals the cellular prion protein, PrP, to be a major receptor for Ab oligomers, considered the most toxic form of Ab. Ab oligomers suppress LTP signal in murine hippocampal slices but activity remains when pretreated with the PrP monoclonal antibody, 6D11, which binds competitively to PrP. Targeting of PrP to prevent Ab oligomer-related cognitive deficits is a potential novel therapeutic target. Methods: APP/PS1 transgenic mice aged 8 months were intraperitoneally (i.p.) injected with 1mg 6D11 daily for 2 weeks (n 1⁄4 10). For controls, APP/PS1 (n 1⁄4 7) and wild-type mice (n 1⁄4 8) were given i.p. control injections. The mice were then subjected to behavioral testing by radial arm maze to assess the effect of 6D11 treatment on cognition. Animals adapted to their environment for 3 days before 7 consecutive days of training sessions. Animals were then tested for 10 days where each of the 8 arms was baited with sugar water. Water-restricted mice were permitted to enter every arm until all 8 rewards were consumed. The number of errors was recorded for each mouse each day. At the conclusion of behavioral testing, animals were sacrificed and brain tissue will be analyzed biochemically and immunohistochemically for the presence of amyloid plaques and Ab oligomers. Results: Behavioral tests show a marked decrease in errors between APP/PS1 treated and non-treated groups (p < 0.0001). Treated APP/PS1 Tg mice behaved the same as wild-type controls indicating a recovery in cognitive learning, even after this short term 6D11 treatment. Brain tissue samples from both treated and non-treated APP/ PS1 groups indicate no significant differences in amyloid plaque burden, suggesting the cognitive effects were due to 6D11-PrP interactions. Conclusions: Monoclonal antibodies such as 6D11 or other compounds with a high affinity for PrP can be used to treat cognitive deficits in aged AD transgenic mice by competitively binding the major Ab oligomer receptor.

Intracerebroventricular infusion of monoclonal antibody or its derived Fab fragment against misfolded forms of SOD1 mutant delays mortality in a mouse model of ALS

The finding of a secretion pathway and toxicity for mutant superoxide dismutase 1 (SOD1) raised up the possibility of using immunization approaches to reduce or neutralize the burden of toxic SOD1 species in the nervous system. Here we tested a passive immunization approach based on intracerebroventricular infusion in G93A-SOD1 mice of monoclonal antibodies specific to misfolded forms of SOD1 (mSOD1). We tested two monoclonal antibodies that bind distinct epitopes in mSOD1 and that do not bind to intact wild-type (WT) SOD1. One antibody succeeded in reducing the level of mSOD1 by 23% in the spinal cord and in prolonging the lifespan of G93A-SOD1 mice in proportion to the duration of treatment. However, another monoclonal antibody binding to a different SOD1 epitope failed to confer protection indicating that not all anti-SOD1 antibodies might be suitable for immunotherapy. Interestingly, the variable Fab fragment of an anti-SOD1 antibody was sufficient to confer some protection in G93A-SOD1 mice. The partial dispensability of Fc region should offer some advantages for development of immunotherapy with antibodies of smaller molecular size and low immunogenicity. From these results, we propose that passive immunization strategies should be considered as potential avenues for treatment of familial amyotrophic lateral sclerosis caused by SOD1 mutations.

Anti-Cytokine Therapeutics: History and Update

Anti-cytokine therapy has promoted a revolution in the treatment of several inflammatory disorders during the past 10 years. Despite their medical and commercial success, they exhibit several drawbacks: difficulties of production, excessive costs, and a few side-effects. A promising alternative to the passive infusion of monoclonal antibodies or soluble cytokine receptors is the use of the active anti-cytokine immune therapy (ACIT). Surprisingly, clinical studies suggested the interest of this approach during the late 1980's, even before the advent of anti-cytokine passive immunotherapy. In this review, we first explain the involvement of several cytokines in many common diseases involving cytokine overproduction, and identify key targets for anti-cytokine treatments. We then present an update on current advances in preclinical and clinical development of passive anti-cytokine therapeutic approaches. We further discuss progresses in the promising field of active anti-cytokine immunotherapy. Cytokine receptors biologics and small molecules developed using structure/function information, which also constitute important options for treating the cytokine-mediated diseases, are not discussed in this review.

A case of “refractory” lupus erythematosus profundus responsive to rituximab [case report

Lupus erythematosus profundus is a rare complication of systemic lupus erythematosus characterized by the presence of deep, tender subcutaneous nodules. A 22-year-old African-American female with extensive lupus profundus resistant to conventional therapies was treated with two infusions of the anti-CD20 monoclonal antibody, rituximab, at a dosage of 1,000 mg each. The patient demonstrated a remarkable clinical response as indicated by the disappearance of the nodules. B-cell depletion therapy with rituximab used alone or in combination with other therapies may be a viable option in patients with lupus profundus refractory to current therapies.

An audit of hospital based outpatient infusions and a pilot program of community-based monoclonal antibody infusions

Infliximab, a chimeric monoclonal antibody to tumour necrosis factor alpha, is administered as an intravenous infusion requiring a costly hospital day case or inpatient admission. An audit of all current therapies given by intravenous infusions in an outpatient setting in St Vincent's University Hospital (SVUH) was undertaken. Furthermore, in conjunction with TCP homecare, we established in a general practise health clinic, the first Irish community infusion centre for the administration of infliximab in August 2006. All outpatient departments indicated that they would favour a centralized hospital infusion unit. There were no adverse events and the mean global satisfaction improved in the community infliximab infusion pilot programme of seven patients. This study suggests efficiencies in providing centralized infusion facilities, while the community based infusion of infliximab is feasible and safe in this small cohort and identifies the community infusion unit as a viable and cost efficient alternative for administration of infliximab.

INTRAPARENCHYMAL AND INTRATUMORAL INTERSTITIAL INFUSION OF ANTI-GLIOMA MONOCLONAL ANTIBODY 8H9

Interstitial infusion, a form of local delivery that bypasses the blood-brain barrier, has been shown to afford high regional concentrations of a therapeutic molecule while avoiding systemic exposure. The distribution of monoclonal antibodies administered via interstitial infusion has not been characterized, and this is salient in light of the potential sequestration by epitopes expressed by targeted tissue. Interstitial delivery of murine immunoglobulin G1 monoclonal antibody (MAb) 8H9 was investigated in a rodent model for the potential treatment of infiltrative gliomas. MAb 8H9 was infused in varying concentrations and volumes into previously untreated animals and into an immunoreactive U87 xenograft to evaluate distributive potential. Previously untreated animals and athymic rats bearing U87 xenografts underwent variable infusions into the striatum or grafted tumor, respectively. Animals were sacrificed at multiple time points, and the volume of 8H9 distribution was determined using a new semiautomated technique. Increasing both the volume and dose of 8H9 infusion increased the volume of distribution. Distribution was significantly greater at 24 hours after infusion than at 1 hour. Interstitial infusion of MAb 8H9 resulted in a positive relationship between the volume of distribution and either the infusion volume or infusion dose. No significant difference in the volume of distribution was seen between antibodies in naïve striatum and U87 xenografts. Antibody distribution was effectively augmented by convection and diffusion after delivery. Finally, intratumoral interstitial infusion of a reactive MAb has been performed similarly to delivery to a normal brain. This finding is encouraging from a therapeutic standpoint, given the clinical need to affect large domains of these infiltrative tumors.

Implications of IV monoclonal antibody infusion reaction for the patient, caregiver, and practice: results of a multicenter study

Targeted monoclonal antibodies (MoAbs) have become a promising treatment option for patients with cancer. However, there is a risk of developing infusion reactions (IRs) with MoAbs. This study was conducted to evaluate the impact of IRs on staff time and costs among patients receiving an initial infusion of cetuximab (Erbitux) and rituximab (Rituxan). A prospective multicenter study involving time and motion and activity sampling methods was conducted among patients with cancer receiving their first outpatient infusion of cetuximab or rituximab. Patients were observed from initiation of MoAb infusion to the end of the clinic visit. IRs were classified as absent, mild/moderate, and severe/life threatening. Staff time and costs were estimated for preparation and administration of MoAb, other chemotherapy agents, and for management of IRs. Resource costs were compared across IR groups within each MoAb. Among 161 patients enrolled, 32% of 71 patients on cetuximab and 39% of 90 patients on rituximab experienced IRs. Treatment of patients who experienced IRs required more staff time (31-80% more time) and resulted in higher human resource costs (increase of 17-65 US dollars) than patients who did not experience IRs. IRs following cetuximab and rituximab administration are common and are associated with measurably increased costs of care. The frequency of IRs suggests the importance of identifying clinical guidelines for intervention and management.

Effect of intraventricular infusion of anti-prion protein monoclonal antibodies on disease progression in prion-infected mice

It is well known that anti-prion protein (PrP) monoclonal antibodies (mAbs) inhibit abnormal isoform PrP (PrPSc) formation in cell culture. Additionally, passive immunization of anti-PrP mAbs protects the animals from prion infection via peripheral challenge when mAbs are administered simultaneously or soon after prion inoculation. Thus, anti-PrP mAbs are candidates for the treatment of prion diseases. However, the effects of mAbs on disease progression in the middle and late stages of the disease remain unclear. This study carried out intraventricular infusion of mAbs into prion-infected mice before and after clinical onset to assess their ability to delay disease progression. A 4-week infusion of anti-PrP mAbs initiated at 120 days post-inoculation (p.i.), which is just after clinical onset, reduced PrPSc levels to 70-80 % of those found in mice treated with a negative-control mAb. Spongiform changes, microglial activation and astrogliosis in the hippocampus and thalamus appeared milder in mice treated with anti-PrP mAbs than in those treated with a negative-control mAb. Treatment with anti-PrP mAb prolonged the survival of mice infected with Chandler or Obihiro strain when infusion was initiated at 60 days p.i., at which point PrPSc is detectable in the brain. In contrast, infusion initiated after clinical onset prolonged the survival time by about 8 % only in mice infected with the Chandler strain. Although the effects on survival varied for different prion strains, the anti-PrP mAb could partly prevent disease progression, even after clinical onset, suggesting immunotherapy as a candidate for treatment of prion diseases.

Amyloid β Protein Dimer-Containing Human CSF Disrupts Synaptic Plasticity: Prevention by Systemic Passive Immunization

The current development of immunotherapy for Alzheimer's disease is based on the assumption that human-derived amyloid beta protein (Abeta) can be targeted in a similar manner to animal cell-derived or synthetic Abeta. Because the structure of Abeta depends on its source and the presence of cofactors, it is of great interest to determine whether human-derived oligomeric Abeta species impair brain function and, if so, whether or not their disruptive effects can be prevented using antibodies. We report that untreated ex vivo human CSF that contains Abeta dimers rapidly inhibits hippocampal long-term potentiation in vivo and that acute systemic infusion of an anti-Abeta monoclonal antibody can prevent this disruption of synaptic plasticity. Abeta monomer isolated from human CSF did not affect long-term potentiation. These results strongly support a strategy of passive immunization against soluble Abeta oligomers in early Alzheimer's disease.

A critical role for extracellular protein disulfide isomerase during thrombus formation in mice

Thiol isomerases, including protein disulfide isomerase (PDI), catalyze disulfide oxidation, reduction, and isomerization, thereby playing an important role in protein synthesis. To determine whether extracellular PDI mediates thrombus formation in an animal model, PDI expression, platelet accumulation, and fibrin generation were monitored in the blood vessels of mice by intravital fluorescence microscopy following laser-induced arteriolar injury. A time-dependent increase in PDI was observed in murine thrombi following injury. Infusion of the PDI inhibitor bacitracin or a blocking monoclonal antibody against PDI inhibited platelet thrombus formation and fibrin generation. Fibrin deposition is normal in mice lacking the G protein-coupled platelet receptor Par4, although there is no stable accumulation of platelets. Infusion of monoclonal antibodies against PDI into the circulation of Par4(-/-) mice prior to vessel wall injury inhibited fibrin generation. These results indicate that PDI is required in vivo in mice for both fibrin generation and platelet thrombus formation.

Protein Disulfide Isomerase Is Required for Fibrin Generation and Platelet Thrombus Formation In Vivo.

Thiol isomerases catalyze disulfide oxidation, reduction and isomerization, playing an important role during protein synthesis. Recent studies suggest a role for protein disulfide isomerase (PDI), a prototype of the thiol isomerase family, in platelet function and regulation of tissue factor activity (Essex and Li. Curr Drug Targets. 2006; Chen and Hogg. J Thromb Haemost. 2006). To determine the role of intravascular PDI during thrombus formation, PDI expression, platelet accumulation, and fibrin generation were monitored following laser-induced arteriolar injury in the mouse cremaster muscle by intravital fluorescence microscopy. PDI antigen exhibited a time-dependent increase in the developing thrombus after vessel wall injury and remained associated with the thrombus. Infusion of bacitracin, a non-specific inhibitor of thiol isomerases, into the circulation inhibited platelet thrombus formation and fibrin generation in a dose-dependent manner. Infusion of a function-blocking monoclonal antibody to PDI (RL90) into the circulation of a wild type mouse also resulted in dose-dependent inhibition of platelet accumulation and fibrin generation. To determine whether PDI inhibits fibrin formation by blocking tissue factor activation, or by preventing platelet activation and the development of the membrane surface that is required for assembly of the tenase and the prothrombinase complex in vivo, we explored fibrin formation in mice lacking protease-activated receptor-4 (Par4). Although there is no stable accumulation of platelets and no platelet activation, fibrin formation is normal in the Par4 null mouse (Vandendries et al, Proc Natl Acad Sci USA. 2007), suggesting that fibrin generation in the laser-induced vessel injury model is independent of platelet activation. Infusion of the function-blocking anti-PDI antibody (RL90) into the circulation of a Par4 null mouse prior to vessel wall injury inhibited fibrin generation. These results indicate that PDI is required to generate tissue factor in a form that leads to thrombin generation and fibrin formation during thrombus development and is required for thrombus formation.

Tumor Necrosis Factor Blockade: Mechanism of Action

Modulation of the immune response with tumor necrosis factor (TNF) blockers is not a new treatment strategy for many inflammatory disorders; however, relatively little is known about their specific mechanism of action. Understanding the mode of action, pharmacology, and pharmacokinetics of the monoclonal TNF antibodies, infliximab and adalimumab, and the soluble TNF receptor, etanercept, may therefore enable us to account for their differing clinical profiles. The aim of this supplement is to explore the roles and mechanisms of TNF and TNF blockade using in vitro pharmacological and in vivo animal modeling experiments, and in vivo studies of the effects of etanercept on the inflammatory cascade in patients with psoriasis.