scholarly journals The monoclonal antibody 26 raised against tetanus toxoid also recognizes tetanus toxin and β2-glycoprotein I - its binding properties in vitro and potential applications

2009 ◽  
Vol 74 (3) ◽  
pp. 245-257 ◽  
Author(s):  
Aleksandra Inic-Kanada ◽  
Marijana Stojanovic ◽  
Irena Zivkovic ◽  
Vladimir Petrusic ◽  
Ljiljana Dimitrijevic
Keyword(s):  
Tetanus Toxoid ◽  
Tetanus Toxin ◽  
Molecular Mimicry ◽  
Cross Reactivity ◽  
Affinity Constant ◽  
Glycoprotein I ◽  
Relative Affinity ◽  
Potential Applications ◽  
Scatchard Plots

A murine monoclonal IgG1 antibody, marked as MAb26, specific for tetanus toxoid has been immunochemically characterized. By performing enzyme-linked immunosorbent assays (ELISAs) and western blot analyses, it was demonstrated that MAb26 reacted with tetanus toxoid, tetanus toxin and ?2-glycoprotein I (?2GPI). According to the results, MAb26 recognized the sequential epitope on the tetanus heavy chain. The affinity constant, calculated from Scatchard plots of MAb26 binding to tetanus toxoid, was 1.145?108 M-1 and the measurement of the relative affinity of MAb26 by ELISA using thiocyanate elution showed a significantly higher affinity of MAb26 to the toxoid (p = 0.0012) in comparison to the toxin. Additionally, the reactivity of MAb26 toward the toxoid forms increased when the tetanus toxin was detoxified using 8 mM and higher formaldehyde concentrations. The similarity of the tetanus toxoid to several sera proteins, either at the level of its conformation (IL-1?) or at the level of peptide sequences (?2GPI, laminin) favors its role in autoimmunity by the mechanism of molecular mimicry. As the induction of an autoimmune disease is dependent on the breakdown of tolerance, which could be the result of an overt hyperstimulation, the control of the presence and concentration of self-reactive epitopes in vaccine preparations is a prerequisite. In this study, it was shown that MAb26 can: 1) discriminate between the tetanus toxin and different toxoid forms, which makes it a good candidate for antibody control during vaccine preparation; 2) due to its cross-reactivity with ?2GPI, it could provide information on the presence of a potentially dangerous sequential epitope expressed at the protein surface.

scholarly journals Beta 2-glycoprotein I is a requirement for anticardiolipin antibodies binding to activated platelets: differences with lupus anticoagulants

Blood ◽  
1993 ◽  
Vol 81 (5) ◽  
pp. 1255-1262 ◽  
Author(s):  
W Shi ◽  
BH Chong ◽  
CN Chesterman
Keyword(s):  
Cross Reactivity ◽  
Anticardiolipin Antibodies ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Glycoprotein I ◽  
Activated Platelets ◽  
Major Interest ◽  
Thrombin Activation ◽  
Beta 2

Abstract Antiphospholipid (aPL) antibodies are of major interest not only because the lupus anticoagulant (LA) causes an inhibition of in vitro blood coagulation, but also because the presence of aPL antibodies confers a risk of thrombosis. The inhibition of in vitro phospholipid- dependent coagulation (LA) is thought to be caused by the binding of LA to procoagulant phospholipid surfaces, thus impeding the clotting process. Another class of aPL antibodies are those originally described to be directed against negatively charged phospholipids, in particular cardiolipin (ACA). ACA are usually directed against a complex antigen consisting of negatively charged phospholipid and a plasma protein, beta 2-glycoprotein I (beta 2-GPI). Further, there is antibody heterogeneity even within individual patients so that ACA and LA are separable using physicochemical techniques such as ion exchange chromatography and chromatofocusing. Using such techniques we have enriched Ig fractions for LA and ACA from two patient plasmas. The majority of Ig with LA activity had a pI of 7.2 to 7.3 whereas ACA had a pI of 5.0 to 5.2. Using these enriched fractions labeled with [125I]- iodine we have shown that LA binds to platelets in a specific and saturable manner. Binding is dependent on thrombin activation. [125I]- ACA behaves differently. Like LA, binding is specific and dependent on thrombin activation but in this case requires the presence of beta 2- GPI. ACA, in the presence of beta 2-GPI, competes for binding with LA suggesting the same or contiguous site. There is no cross-reactivity of these antibodies with GPIIb/IIIa and the most likely binding site is phospholipid. In neither case does LA nor ACA have an effect on thrombin-induced release of serotonin or beta-thromboglobulin nor do they affect platelet aggregation induced by a number of agonists. This antibody binding may play an etiological role in thrombocytopenia associated with aPL, but does not explain thrombosis on the basis of hyperaggregability or increased platelet release.

scholarly journals Case Report: Circulating Anti-SARS-CoV-2 Antibodies Do Not Cross-React With Pemphigus or Pemphigoid Autoantigens

2021 ◽  
Vol 8 ◽  
Author(s):  
Michael Kasperkiewicz ◽  
Marta Bednarek ◽  
Stefan Tukaj
Keyword(s):  
Molecular Mimicry ◽  
Case Series ◽  
Cross Reactivity ◽  
Limited Information ◽  
Serum Samples ◽  
Type Vii Collagen ◽  
Autoimmune Bullous Diseases ◽  
Extracellular Molecules ◽  
Immunogenic Proteins

It is hypothesized that SARS-CoV-2 has the potential to elicit autoimmunity due to molecular mimicry between immunogenic proteins of the virus and human extracellular molecules. While in silico and in vitro evaluation of such immune cross-reactivity of human antibodies to SARS-CoV-2 proteins with several different tissue antigens has been described, there is limited information specifically pertaining to the immunological effects of COVID-19 and vaccines against SARS-CoV-2 on the development of autoimmune bullous diseases (AIBDs). Twelve seropositive post-COVID-19 individuals and 12 seropositive healthy volunteers who received two doses of the mRNA COVID-19 vaccine from Pfizer-BioNTech have been included in this case series investigation. Serum samples of these blood donors were tested for autoantibodies to the main immunobullous autoantigens, i.e., desmoglein 1, desmoglein 3, envoplakin, BP180, BP230, and type VII collagen. Our study revealed that none of the 24 anti-SARS-CoV-2 IgG-positive subjects had concomitant antibody reactivity with any of the tested autoantigens. These results argue against a relationship between SARS-CoV-2 infection/vaccines and AIBDs with respect to disease-triggering antibody cross-reactivity.

Thrombogenicity of β2-glycoprotein I–dependent antiphospholipid antibodies in a photochemically induced thrombosis model in the hamster

Blood ◽  
2003 ◽  
Vol 101 (1) ◽  
pp. 157-162 ◽  
Author(s):  
Milosz Jankowski ◽  
Ingrid Vreys ◽  
Christine Wittevrongel ◽  
Doris Boon ◽  
Jos Vermylen ◽  
...  
Keyword(s):  
Antiphospholipid Antibodies ◽  
Arterial Thrombosis ◽  
Thrombus Formation ◽  
Immunohistochemical Analysis ◽  
Cross Reactivity ◽  
High Dose ◽  
Thrombosis Model ◽  
Glycoprotein I ◽  
Antigen Antibody

Abstract We previously showed that β2-glycoprotein I (β2GPI)–dependent lupus anticoagulants (LAs) form bivalent antigen-antibody complexes with high affinity for phospholipids; these complexes are responsible for their in vitro anticoagulant effect. We now studied the role of these bivalent complexes in arterial thrombosis in the hamster. Three monoclonal antibodies (mAbs) raised against human β2GPI were selected on the basis of their cross-reactivity with hamster β2GPI. Two of these, one with LA activity, 5H2, and one with only anticardiolipin properties, 11E8, were infused at 0 to 10 mg/kg prior to photochemically induced vessel damage. 5H2 promoted thrombus formation dose dependently, raising the thrombus size from 6.0 arbitrary units (AU) in controls (n = 9) to 65.0 AU in the high-dose group (10 mg/kg, n = 6, P = .007). The LA−mAb 11E8 and mAb 27A8, reactive with human β2GPI exclusively, did not significantly promote thrombus formation. In a second set of experiments, intact mAb 5H2 was compared to its fragments. Intact mAb 5H2 at 3.3 mg/kg and the equimolar dose of F(ab′)2 fragments (2.2 mg/kg) promoted thrombus formation equally well (55.8 AU, n = 8 and 62.5 AU, n = 7, respectively); mAb 5H2-derived Fab′ fragments were inactive. Immunohistochemical analysis showed platelet-rich thrombi, with 5H2 or its F(ab′)2fragments mainly bound to individual platelets. Our results indicate that bivalent immune complex formation plays an important role in the genesis of arterial thrombosis by certain antiphospholipid antibodies. Cellular activation via the Fc portion of these immune complexes, however, is not essential, because F(ab′)2 fragments of 5H2 still promote thrombus formation.

scholarly journals Revisiting the phosphotyrosine binding pocket of Fyn SH2 domain led to the Identification of novel SH2 superbinders

2020 ◽  
Author(s):  
Shuhao Li ◽  
Yang Zou ◽  
Dongping Zhao ◽  
Yuqing Yin ◽  
Jingyi Song ◽  
...  
Keyword(s):  
Directed Evolution ◽  
Binding Pocket ◽  
Cross Reactivity ◽  
Dissociation Rate ◽  
Sh2 Domain ◽  
Binding Affinities ◽  
Wild Type ◽  
Triple Mutant ◽  
Potential Applications

AbstractProtein engineering through directed evolution is an effective way to obtain proteins with novel functions with the potential applications as tools for diagnosis or therapeutics. Many natural proteins, largely antibodies as well as some non-antibody proteins, have undergone directed evolution in vitro in the test tubes in the laboratories around the world, resulted in the numerous protein variants with novel or enhanced functions. In this study, we constructed a Fyn SH2 variant library by randomizing the 8 variable residues in its phosphotyrosine (pTyr) binding pocket. Selection of this library by a pTyr peptide from MidT antigen led to the identification of SH2 variants with enhanced affinities to the peptide, compared to the wild type SH2, by EC50 assay. Fluorescent polarization (FP) was then applied to quantify the binding affinity of the newly identified SH2 variants. As a result, three SH2 variants, named V3, V13 and V24, have comparable binding affinities with the previously identified SH2 triple-mutant superbinder (refer to Trm). Biolayer Interferometry (BLI) assay was employed to disclose the kinetics of the binding of these SH2 superbinders, in addition to the wild type SH2, to the phosphotyrosine peptide. The results indicated that all the SH2 superbinders have two-orders increase of the dissociation rate when binding the pTyr peptide while there was no significant change in their associate rates. The previously identified SH2 superbinder Trm as well as the V13 and V24 discovered in this study have cross-reactivity with the sulfotyrosine (sTyr) containing peptide while the wild type SH2 does not. Intriguingly, though binding the pTyr peptide with comparable affinity with other SH2 superbinders, the V3 does not bind to the sTyr peptide, implying it binds to the pTyr peptide with a different pattern from the other superbinders. The newly identified superbinders could be utilized as tools for the identification of pTyr-containing proteins from tissues under different physiological or pathophysiological conditions and may have the potential in the therapeutics.

scholarly journals Beta 2-glycoprotein I is a requirement for anticardiolipin antibodies binding to activated platelets: differences with lupus anticoagulants

Blood ◽  
1993 ◽  
Vol 81 (5) ◽  
pp. 1255-1262 ◽  
Author(s):  
W Shi ◽  
BH Chong ◽  
CN Chesterman
Keyword(s):  
Cross Reactivity ◽  
Anticardiolipin Antibodies ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Glycoprotein I ◽  
Activated Platelets ◽  
Major Interest ◽  
Thrombin Activation ◽  
Beta 2

Antiphospholipid (aPL) antibodies are of major interest not only because the lupus anticoagulant (LA) causes an inhibition of in vitro blood coagulation, but also because the presence of aPL antibodies confers a risk of thrombosis. The inhibition of in vitro phospholipid- dependent coagulation (LA) is thought to be caused by the binding of LA to procoagulant phospholipid surfaces, thus impeding the clotting process. Another class of aPL antibodies are those originally described to be directed against negatively charged phospholipids, in particular cardiolipin (ACA). ACA are usually directed against a complex antigen consisting of negatively charged phospholipid and a plasma protein, beta 2-glycoprotein I (beta 2-GPI). Further, there is antibody heterogeneity even within individual patients so that ACA and LA are separable using physicochemical techniques such as ion exchange chromatography and chromatofocusing. Using such techniques we have enriched Ig fractions for LA and ACA from two patient plasmas. The majority of Ig with LA activity had a pI of 7.2 to 7.3 whereas ACA had a pI of 5.0 to 5.2. Using these enriched fractions labeled with [125I]- iodine we have shown that LA binds to platelets in a specific and saturable manner. Binding is dependent on thrombin activation. [125I]- ACA behaves differently. Like LA, binding is specific and dependent on thrombin activation but in this case requires the presence of beta 2- GPI. ACA, in the presence of beta 2-GPI, competes for binding with LA suggesting the same or contiguous site. There is no cross-reactivity of these antibodies with GPIIb/IIIa and the most likely binding site is phospholipid. In neither case does LA nor ACA have an effect on thrombin-induced release of serotonin or beta-thromboglobulin nor do they affect platelet aggregation induced by a number of agonists. This antibody binding may play an etiological role in thrombocytopenia associated with aPL, but does not explain thrombosis on the basis of hyperaggregability or increased platelet release.

Role of molecular mimicry and polyclonal cell activation in the induction of pathogenic β2-glycoprotein I–directed immune response in Balb/c mice upon hyperimmunization with tetanus toxoid

2012 ◽  
Vol 56 (1) ◽  
pp. 20-31 ◽  
Author(s):  
Marijana Stojanović ◽  
Vladimir Petrušić ◽  
Irena Živković ◽  
Aleksandra Inić-Kanada ◽  
Ivana Stojićević ◽  
...  
Keyword(s):  
Immune Response ◽  
Tetanus Toxoid ◽  
Cell Activation ◽  
Molecular Mimicry ◽  
Glycoprotein I

scholarly journals Potent neutralization of 2019 novel coronavirus by recombinant ACE2-Ig

2020 ◽  
Author(s):  
Changhai Lei ◽  
Wenyan Fu ◽  
Kewen Qian ◽  
Tian Li ◽  
Sheng Zhang ◽  
...  
Keyword(s):  
Fusion Proteins ◽  
Antiviral Treatment ◽  
Cross Reactivity ◽  
Cell Entry ◽  
Receptor Binding Domain ◽  
Potential Applications ◽  
Novel Coronavirus ◽  
Entry Receptor ◽  
Potent Neutralization

Abstract2019-nCoV, which is a novel coronavirus emerged in Wuhan, China, at the end of 2019, has caused at least infected 11,844 as of Feb 1, 2020. However, there is no specific antiviral treatment or vaccine currently. Very recently report had suggested that novel CoV would use the same cell entry receptor, ACE2, as the SARS-CoV. In this report, we generated a novel recombinant protein by connecting the extracellular domain of human ACE2 to the Fc region of the human immunoglobulin IgG1. An ACE2 mutant with low catalytic activity was also used in the study. The fusion proteins were then characterized. Both fusion proteins has high affinity binding to the receptor-binding domain (RBD) of SARS-CoV and 2019-nCoV and exerted desired pharmacological properties. Moreover, fusion proteins potently neutralized SARS-CoV and 2019-nCoV in vitro. As these fusion proteins exhibit cross-reactivity against coronaviruses, they could have potential applications for diagnosis, prophylaxis, and treatment of 2019-nCoV.

Delayed hypersensitivity to tetanus toxoid in man: in vivo and in vitro studies

Pathology ◽  
1983 ◽  
Vol 15 (4) ◽  
pp. 369-372 ◽  
Author(s):  
Christine Johnson ◽  
R.S. Walls ◽  
A. Ruwoldt
Keyword(s):  
Tetanus Toxoid ◽  
In Vitro Studies ◽  
Delayed Hypersensitivity

scholarly journals Selection and Micropropagation of an Elite Melatonin Rich Tulsi (Ocimum sanctum L.) Germplasm Line

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 207
Author(s):  
Mukund R. Shukla ◽  
Annaliese Kibler ◽  
Christina E. Turi ◽  
Lauren A. E. Erland ◽  
J. Alan Sullivan ◽  
...  
Keyword(s):  
In Vitro Selection ◽  
Integrated Approach ◽  
Antioxidant Potential ◽  
Ocimum Sanctum ◽  
Natural Health Products ◽  
Seed Population ◽  
Health Products ◽  
Potential Applications ◽  
Medicinal Properties

Tulsi (Ocimum sanctum L.) is a sacred plant of medicinal and spiritual significance in many cultures. Medicinal properties of Tulsi are ascribed to its phytochemicals with antioxidant capabilities. The current study was undertaken to screen a large seed population of Tulsi to select germplasm lines with high antioxidant potential and to standardize protocols for micropropagation and biomass production to produce a phytochemically consistent crop. A total of 80 germplasm lines were established under in vitro conditions and screened for their antioxidant potential determined with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) bioassay. The micropropagation of a selected line, named Vrinda, was established using nodal cultures grown on Murashige and Skoog medium containing benzylaminopurine (1.1 µM), gibberellic acid (0.3 µM), and activated charcoal (0.6%). The antioxidant phytohormones melatonin and serotonin were quantified in the field and greenhouse grown tissues of Vrinda and melatonin levels were found to be consistent in both conditions with higher serotonin levels under field conditions. This integrated approach combining the in vitro selection and propagation offers potential applications in the development of safe, effective, and novel natural health products of Tulsi, and many other medicinal plant species.

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