Scott K Dessain

Lankenau Institute for Medical Research, Wynnewood, Oklahoma, United States

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Publications (39)234.15 Total impact

  • No preview · Article · Aug 2015 · Cancer Research
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    ABSTRACT: Alzheimer's disease (AD) and familial Danish dementia (FDD) are degenerative neurological diseases characterized by amyloid pathology. Normal human sera contain IgG antibodies that specifically bind diverse preamyloid and amyloid proteins and have shown therapeutic potential in vitro and in vivo. We cloned one of these antibodies, 3H3, from memory B cells of a healthy individual using a hybridoma method. 3H3 is an affinity-matured IgG that binds a pan-amyloid epitope, recognizing both Aβ and λ Ig light chain (LC) amyloids, which are associated with AD and primary amyloidosis, respectively. The pan-amyloid-binding properties of 3H3 were demonstrated using ELISA, immunohistochemical studies, and competition binding assays. Functional studies showed that 3H3 inhibits both Aβ and LC amyloid formation in vitro and abrogates disruption of hippocampal synaptic plasticity by AD-patient-derived soluble Aβ in vivo. A 3H3 single-chain variable fragment (scFv) retained the binding specificity of the 3H3 IgG and, when expressed in the brains of transgenic mice using an adeno-associated virus (AAV) vector, decreased parenchymal Aβ amyloid deposition in TgCRND8 mice and ADan (Danish Amyloid) cerebral amyloid angiopathy in the mouse model of FDD. These data indicate that naturally occurring human IgGs can recognize a conformational, amyloid-specific epitope and have potent anti-amyloid activities, providing a rationale to test their potential as antibody therapeutics for diverse neurological and other amyloid diseases.
    No preview · Article · Apr 2015 · The Journal of Neuroscience : The Official Journal of the Society for Neuroscience

  • No preview · Article · Oct 2014 · Cancer Research
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    ABSTRACT: An essential requirement for eradication of poliomyelitis is the elimination of circulating vaccine derived polioviruses (cVDPV) and polioviruses excreted by chronically infected individuals with immunodeficiencies (iVDPV). As part of a post-eradication risk management strategy, a human monoclonal antibody (mAb) therapeutic could play a role in halting excretion in asymptomatic carriers and could be used, in combination with vaccines and antiviral drugs, to protect polio-exposed individuals. Cross-neutralizing mAbs may be particularly useful, as they would reduce the number of mAbs needed to create a comprehensive PV therapeutic. We cloned a panel of IgG mAbs from OPV-vaccinated, IPV-boosted healthy subjects. Many of the mAbs had potent neutralizing activities against PV wild-type (WT) and Sabin strains, and two of the mAbs, 12F8 and 1E4, were significantly cross-reactive against types 1 and 2 and types 1 and 3, respectively. Mapping the binding epitopes using strains resistant to neutralization (escape mutants) suggested that cross-specific PV binding epitopes may primarily reside within the canyon region, which interacts with the cellular receptor molecule CD155 and the cross-neutralizing chimpanzee/human mAb, A12. Despite their close proximity, the epitopes for the 12F8 and 1E4 mAbs on Sabin 1 were not functionally identical to the A12 epitope. When tested together, 12F8 and 1E4 neutralized a diverse panel of clinically relevant PV strains and did not exhibit interference. Virus mutants resistant to the anti-poliovirus drug V-073 were also neutralized by the mAbs. The 12F8 and 1E4 mAbs may suitable for use as anti-PV therapeutics.
    No preview · Article · May 2014 · Antiviral research
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    ABSTRACT: Although the World Health Organization recommends the use of in vitro techniques to qualify rabies vaccine lot release, very limited proposals have been made to arrive at a harmonized approach for wide scale usage. The present study proposed and evaluated the use of a novel avidin-biotin ELISA as an alternative to these in vivo tests in rabies vaccine manufacture. This assay utilized a neutralizing pan reactive monoclonal antibody (mAb) reactive with the conserved site-II of the natively folded rabies glycoprotein. Linear regression analysis of the in vitro glycoprotein estimates with the in vivo potency values, showed a good correlation (r(2)=0.8) with veterinary vaccines, but a poor correlation (r(2)=0.2) with human vaccines. However, we could qualitatively arrive at cut-off glycoprotein estimates from the ELISA, above which all the vaccines were declared to be protective by mouse challenge studies (>2.5IU/dose).
    Full-text · Article · Nov 2013 · Vaccine
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    ABSTRACT: Immune complexes formed between monoclonal antibodies (mAbs) and toxins can neutralize toxicity in vivo by multiple mechanisms. Toxin sequestration and clearance by mAbs may be improved by enhancing their ability to bind to red blood cells (RBCs) through immune adherence. This can be achieved by converting the mAbs to heteropolymers (HPs), which are antigen-specific mAbs cross-linked to mAbs targeting the complement receptor (CR1), a protein that is expressed on the surface of RBCs in primates and mediates delivery of complement C3b-containing immune complexes to tissue macrophages. Conversion of mAbs to HPs has been shown to enhance clearance of multivalent antigens from the blood circulation, but the interaction of HPs with monovalent toxins has not been examined. Using botulinum neurotoxin (BoNT) as a model system, we studied the effect of conversion of a pair of BoNT-specific mAbs into HPs on toxin neutralization and handling in vivo. Two HPs given in combination had 166-fold greater potency than un-modified mAbs, neutralizing 5000 LD50 BoNT, when tested in transgenic mice expressing human CR1 on RBC membranes. Improvement required adherence of BoNT to the RBC in vivo and 2 HPs, rather than an HP+mAb pair. The HP pair bound BoNT to RBCs in the circulation for 2h, in comparison to BoNT-neutralizing anti-serum, which induced no detectable RBC binding. HP pairs exhibited enhanced uptake by peritoneal macrophages in vitro, compared to pairs of mAbs or mAb+HP pairs. In a post-exposure therapeutic model, HPs gave complete protection from a lethal BoNT dose up to 3h after toxin exposure. In a pre-exposure prophylaxis model, mice given HP up to 5 days prior to BoNT administration were fully protected from a lethal BoNT dose. These studies elucidate general mechanisms for the neutralization of toxins by HP pairs and demonstrate the potential utility of HPs as BoNT therapeutics.
    Full-text · Article · Oct 2013 · Molecular Immunology

  • No preview · Article · Jul 2013 · Alzheimer's and Dementia
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    ABSTRACT: Botulinum neurotoxin (BoNT) is produced by Clostridium botulinum and associates with nontoxic neurotoxin-associated proteins to form high-molecular weight progenitor complexes (PCs). The PCs are required for the oral toxicity of BoNT in the context of food-borne botulism and are thought to protect BoNT from destruction in the gastrointestinal tract and aid in absorption from the gut lumen. The PC can differ in size and protein content depending on the C. botulinum strain. The oral toxicity of the BoNT PC increases as the size of the PC increases, but the molecular architecture of these large complexes and how they contribute to BoNT toxicity have not been elucidated. We have generated 2D images of PCs from strains producing BoNT serotypes A1, B, and E using negative stain electron microscopy and single-particle averaging. The BoNT/A1 and BoNT/B PCs were observed as ovoid-shaped bodies with three appendages, whereas the BoNT/E PC was observed as an ovoid body. Both the BoNT/A1 and BoNT/B PCs showed significant flexibility, and the BoNT/B PC was documented as a heterogeneous population of assembly/disassembly intermediates. We have also determined 3D structures for each serotype using the random conical tilt approach. Crystal structures of the individual proteins were placed into the BoNT/A1 and BoNT/B PC electron density maps to generate unique detailed models of the BoNT PCs. The structures highlight an effective platform that can be engineered for the development of mucosal vaccines and the intestinal absorption of oral biologics.
    Full-text · Article · Mar 2013 · Proceedings of the National Academy of Sciences
  • Minal Dhamankar · Scott K Dessain

    No preview · Article · Apr 2012 · Clinical advances in hematology & oncology: H&O

  • No preview · Article · Jul 2011 · Alzheimer's and Dementia
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    ABSTRACT: The emergence of a novel strain of pandemic influenza (pH1N1) in 2009 presented significant challenges to health care facilities worldwide. In our academic community medical center in suburban Philadelphia, we noted our first pH1N1 diagnosis in September 2009. We sought to assess the impact of pH1N1 disease on our hospitalized patient population. We prospectively collected clinical and epidemiological data on 29 consecutive patients that were admitted to our hospital with a primary or secondary diagnosis of influenza from October 1-November 30, 2009. Data were obtained through care of the patients and chart review. Prominent symptoms on admission included fever, hypoxia, cough, myalgias, and diarrhea, with leukocytosis and neutrophilia. Pre-existing medical conditions included asthma, pregnancy, immunosuppressive therapy, and sickle cell disease. All but 5 of the patients were under 60 years of age. Three patients had culture-documented bacterial or mycoplasma infections. All but two of the patients received oseltamivir. Six required admission to the intensive care unit but only one patient died. Our population of hospitalized patients with novel pH1N1 influenza demonstrated many of the features that have been associated with pH1N1 disease in other populations. Most of the patients were women and none of the patients died directly as a complication of influenza. We observed a cluster of patients with a tetrad of features comprising a history of asthma, obesity, female gender, and African-American race. Individuals with this constellation of factors should be specifically targeted for pH1N1 vaccination.
    Preview · Article · Jun 2011 · The Open Respiratory Medicine Journal
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    ABSTRACT: Botulinum neurotoxin (BoNT) potently inhibits cholinergic signaling at the neuromuscular junction. The ideal countermeasures for BoNT exposure are monoclonal antibodies or BoNT antisera, which form BoNT-containing immune complexes that are rapidly cleared from the general circulation. Clearance of opsonized toxins may involve complement receptor-mediated immunoadherence to red blood cells (RBC) in primates or to platelets in rodents. Methods of enhancing immunoadherence of BoNT-specific antibodies may increase their potency in vivo. We designed a novel fusion protein (FP) to link biotinylated molecules to glycophorin A (GPA) on the RBC surface. The FP consists of an scFv specific for murine GPA fused to streptavidin. FP:mAb:BoNT complexes bound specifically to the RBC surface in vitro. In a mouse model of BoNT neutralization, the FP increased the potency of single and double antibody combinations in BoNT neutralization. A combination of two antibodies with the FP gave complete neutralization of 5,000 LD50 BoNT in mice. Neutralization in vivo was dependent on biotinylation of both antibodies and correlated with a reduction of plasma BoNT levels. In a post-exposure model of intoxication, FP:mAb complexes gave complete protection from a lethal BoNT/A1 dose when administered within 2 hours of toxin exposure. In a pre-exposure prophylaxis model, mice were fully protected for 72 hours following administration of the FP:mAb complex. These results demonstrate that RBC-targeted immunoadherence through the FP is a potent enhancer of BoNT neutralization by antibodies in vivo.
    Full-text · Article · Mar 2011 · PLoS ONE

  • No preview · Article · Jul 2010 · Alzheimer's and Dementia
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    ABSTRACT: We have previously shown that a subpopulation of naturally occurring human IgGs were cross-reactive against conformational epitopes on pathologic aggregates of Aβ, a peptide that forms amyloid fibrils in the brains of patients with Alzheimer disease, inhibited amyloid fibril growth, and dissociated amyloid in vivo. Here, we describe similar anti-amyloidogenic activity that is a general property of free human Ig γ heavy chains. A γ1 heavy chain, F1, had nanomolar binding to an amyloid fibril-related conformational epitope on synthetic oligomers and fibrils as well as on amyloid-laden tissue sections. F1 did not bind to native Aβ monomers, further indicating the conformational nature of its binding site. The inherent anti-amyloidogenic activity of Ig γ heavy chains was demonstrated by nanomolar amyloid fibril and oligomer binding by polyclonal and monoclonal human heavy chains that were isolated from inert or weakly reactive antibodies. Most importantly, the F1 heavy chain prevented in vitro fibril growth and reduced in vivo soluble Aβ oligomer-induced impairment of rodent hippocampal long term potentiation, a cellular mechanism of learning and memory. These findings demonstrate that free human Ig γ heavy chains comprise a novel class of molecules for developing potential therapeutics for Alzheimer disease and other amyloid disorders. Moreover, establishing the molecular basis for heavy chain-amyloidogenic conformer interactions should advance understanding on the types of interactions that these pathologic assemblies have with biological molecules.
    Full-text · Article · Nov 2009 · Journal of Biological Chemistry

  • No preview · Article · Jul 2009 · Alzheimer's and Dementia
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    ABSTRACT: The evaluation of antithrombotic agents for secondary stroke prevention has focused on stroke reduction. The aim of this analysis was to focus specifically on the increase in bleeding risk. The annualized rates of total and major bleeding events in secondary stroke prevention trials of antithrombotics were assessed and cross compared. A Medline search for major randomized clinical studies with a follow-up duration of > or =1 year identified 13 studies. Pooled data sets were used to compare mean bleeding rates for aspirin (< or =325 mg/day), clopidogrel, anticoagulants (warfarin and other vitamin K antagonists), aspirin plus clopidogrel, and aspirin plus extended-release dipyridamole (ER-DP). Total bleeding occurred at mean rates of 4.8% with aspirin (< or =325 mg/day) alone, 2.9% with clopidogrel alone, 3.6% with aspirin plus ER-DP, 10.1% with aspirin plus clopidogrel, and 16.8% with anticoagulation. Major bleeding occurred at mean rates of 1% with aspirin (< or =325 mg/day) alone, 0.85% with clopidogrel, 0.93% with aspirin plus ER-DP, 1.7% with aspirin plus clopidogrel, and 2.5% with anticoagulation. In conclusion, the combination of aspirin and clopidogrel is associated with significantly greater bleeding than either aspirin (< or =325 mg/day) or clopidogrel alone. Aspirin plus ER-DP has a greater bleeding rate than clopidogrel but a lower rate than aspirin (< or =325 mg/day) alone.
    No preview · Article · Apr 2009 · The American journal of cardiology
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    ABSTRACT: Hemophagocytic lymphohistiocytosis is an immune-mediated syndrome that typically has a rapidly progressive course that can result in pancytopenia, coagulopathy, multi-system organ failure and death. A 57-year-old Caucasian woman was referred in fulminant hemophagocytic lymphohistiocytosis, with fever, pancytopenia, splenomegaly, mental status changes and respiratory failure. She was found to have stage IV classical Hodgkin lymphoma, in addition to Epstein-Barr virus and cytomegalovirus viremia. Her presentation was preceded by a 3-year prodrome consisting of cytopenia and fever that were partially controlled by steroids and azathioprine. Fulminant hemophagocytic lymphohistiocytosis may follow a prodromal phase that possesses features suggestive of a chronic form of hemophagocytic lymphohistiocytosis, but which may also resemble immune cytopenias of other causes. A diagnosis of hemophagocytic lymphohistiocytosis should be considered in the setting of chronic pancytopenia.
    Preview · Article · Jan 2009 · Journal of Medical Case Reports
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    ABSTRACT: A severe form of encephalitis associated with antibodies against NR1-NR2 heteromers of the NMDA receptor was recently identified. We aimed to analyse the clinical and immunological features of patients with the disorder and examine the effects of antibodies against NMDA receptors in neuronal cultures. We describe the clinical characteristics of 100 patients with encephalitis and NR1-NR2 antibodies. HEK293 cells ectopically expressing single or assembled NR1-NR2 subunits were used to determine the epitope targeted by the antibodies. Antibody titres were measured with ELISA. The effect of antibodies on neuronal cultures was determined by quantitative analysis of NMDA-receptor clusters. Median age of patients was 23 years (range 5-76 years); 91 were women. All patients presented with psychiatric symptoms or memory problems; 76 had seizures, 88 unresponsiveness (decreased consciousness), 86 dyskinesias, 69 autonomic instability, and 66 hypoventilation. 58 (59%) of 98 patients for whom results of oncological assessments were available had tumours, most commonly ovarian teratoma. Patients who received early tumour treatment (usually with immunotherapy) had better outcome (p=0.004) and fewer neurological relapses (p=0.009) than the rest of the patients. 75 patients recovered or had mild deficits and 25 had severe deficits or died. Improvement was associated with a decrease of serum antibody titres. The main epitope targeted by the antibodies is in the extracellular N-terminal domain of the NR1 subunit. Patients' antibodies decreased the numbers of cell-surface NMDA receptors and NMDA-receptor clusters in postsynaptic dendrites, an effect that could be reversed by antibody removal. A well-defined set of clinical characteristics are associated with anti-NMDA-receptor encephalitis. The pathogenesis of the disorder seems to be mediated by antibodies.
    Full-text · Article · Nov 2008 · The Lancet Neurology
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    ABSTRACT: The affinity-matured human antibody repertoire may be ideal as a source for antibody therapeutics against infectious diseases and bioterror agents. Hybridoma methods for cloning these antibodies have many potential advantages, including convenience, high-yield antibody expression, and the ability to capture the antibodies in their native configurations. However, they have been hindered by hybridoma instability and limited accessibility of antigen-specific, class-switched human B-cells. Here, we describe an efficient, three-step method that uses human peripheral blood B-cells to produce stable hybridoma populations that are highly-enriched for affinity-matured human IgG antibodies. Peripheral blood mononuclear cells (PBMCs) are (a) selected for expression of CD27, a marker of post-germinal center B-cells, (b) cultured in vitro to promote B-cell proliferation and class-switching, and (c) fused to a genetically modified myeloma cell line. Using this strategy, we cloned 5 IgG antibodies that bind botulinum neurotoxins (BoNT), the causes of the food-borne paralytic illness, botulism, and Category A Select Bioterror agents. Two of these antibodies bind BoNT with low picomolar affinities. One (30B) is the first high-affinity human antibody to bind serotype B BoNT, and another (6A) is able to neutralize a lethal dose of serotype A BoNT in vivo in pre- and post-exposure models. This optimized hybridoma method will broadly enable access to the native human antibody repertoire.
    No preview · Article · May 2008 · Journal of Immunological Methods
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    ABSTRACT: Affinity-matured human antibodies have demonstrated efficacy as countermeasures for exposure to botulinum neurotoxin (BoNT), which is the cause of the disease botulism category A select bioterror agent. Little is known, however, about the potential role of natural (un-mutated) antibodies in the protective immune response to BoNT. Here we describe the cloning of two human IgM antibodies that bind serotype A BoNT. Both are un-mutated IgM antibodies, consistent with an origin in naive B cells. One of the antibodies is able to fully neutralize a lethal dose of serotype A BoNT in vivo. These results suggest that the natural human antibody repertoire may play a role in protection from exposure to biological toxins.
    No preview · Article · Apr 2008 · Hybridoma (2005)

Publication Stats

4k Citations
234.15 Total Impact Points


  • 2008-2015
    • Lankenau Institute for Medical Research
      Wynnewood, Oklahoma, United States
  • 2009
    • Thomas Jefferson University Hospitals
      Filadelfia, Pennsylvania, United States
  • 2005-2008
    • Thomas Jefferson University
      • • Cardeza Foundation for Hematologic Research
      • • Division of Hospital Medicine
      • • Department of Medical Oncology
      Philadelphia, Pennsylvania, United States
  • 2004
    • Whitehead Institute for Biomedical Research
      Cambridge, Massachusetts, United States
  • 2001-2002
    • Harvard Medical School
      Boston, Massachusetts, United States
  • 1998-2000
    • Massachusetts General Hospital
      Boston, Massachusetts, United States