A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement Binding

The classical complement pathway (CCP) is an essential part of the immune system, activated when complement protein C1 binds to IgG antibody oligomers on the surface of pathogens, infected or malignant cells, culminating in the formation of the membrane attack complex and subsequent cell lysis. IgG...

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Main Authors: Jürgen Strasser, Nikolaus Frischauf, Lukas Schustereder, Andreas Karner, Sieto Bosgra, Aran F. Labrijn, Frank J. Beurskens, Johannes Preiner
Format: Article
Language:English
Published: Wiley-VCH 2025-07-01
Series:Small Science
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Online Access:https://doi.org/10.1002/smsc.202500149
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author Jürgen Strasser
Nikolaus Frischauf
Lukas Schustereder
Andreas Karner
Sieto Bosgra
Aran F. Labrijn
Frank J. Beurskens
Johannes Preiner
author_facet Jürgen Strasser
Nikolaus Frischauf
Lukas Schustereder
Andreas Karner
Sieto Bosgra
Aran F. Labrijn
Frank J. Beurskens
Johannes Preiner
author_sort Jürgen Strasser
collection DOAJ
description The classical complement pathway (CCP) is an essential part of the immune system, activated when complement protein C1 binds to IgG antibody oligomers on the surface of pathogens, infected or malignant cells, culminating in the formation of the membrane attack complex and subsequent cell lysis. IgG oligomers also engage immune effector cells through Fcγ receptors or complement receptors, facilitating antibody‐dependent cellular cytotoxicity and phagocytosis. Understanding the factors that drive IgG oligomerization is thus crucial for improving IgG‐based therapies. Herein, a kinetic model to predict oligomer formation based on IgG concentration, antigen density, IgG subclass, Fc mutants, and oligomerization inhibitors like staphylococcal protein A is developed. The underlying molecular interactions in single molecule force spectroscopy and grating coupled interferometry experiments are characterized. By fitting experimental data from high‐speed atomic force microscopy experiments, key rate constants and thermodynamic parameters, including free energy changes associated with oligomerization and apply the model to predict complement‐mediated lysis in liposomal vesicle‐based assays, are further quantified. The presented mechanistic framework may serve as a basis for optimizing antibody engineering and pharmacokinetic/pharmacodynamic modeling in the context of immunotherapies exploiting the CCP.
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institution Matheson Library
issn 2688-4046
language English
publishDate 2025-07-01
publisher Wiley-VCH
record_format Article
series Small Science
spelling doaj-art-68ef45d6f68f44ed82e7473af8e8fde12025-07-11T03:29:45ZengWiley-VCHSmall Science2688-40462025-07-0157n/an/a10.1002/smsc.202500149A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement BindingJürgen Strasser0Nikolaus Frischauf1Lukas Schustereder2Andreas Karner3Sieto Bosgra4Aran F. Labrijn5Frank J. Beurskens6Johannes Preiner7NASAN University of Applied Sciences Upper Austria 4020 Linz AustriaNASAN University of Applied Sciences Upper Austria 4020 Linz AustriaNASAN University of Applied Sciences Upper Austria 4020 Linz AustriaNASAN University of Applied Sciences Upper Austria 4020 Linz AustriaGenmab 3584 CT Utrecht NetherlandsGenmab 3584 CT Utrecht NetherlandsGenmab 3584 CT Utrecht NetherlandsNASAN University of Applied Sciences Upper Austria 4020 Linz AustriaThe classical complement pathway (CCP) is an essential part of the immune system, activated when complement protein C1 binds to IgG antibody oligomers on the surface of pathogens, infected or malignant cells, culminating in the formation of the membrane attack complex and subsequent cell lysis. IgG oligomers also engage immune effector cells through Fcγ receptors or complement receptors, facilitating antibody‐dependent cellular cytotoxicity and phagocytosis. Understanding the factors that drive IgG oligomerization is thus crucial for improving IgG‐based therapies. Herein, a kinetic model to predict oligomer formation based on IgG concentration, antigen density, IgG subclass, Fc mutants, and oligomerization inhibitors like staphylococcal protein A is developed. The underlying molecular interactions in single molecule force spectroscopy and grating coupled interferometry experiments are characterized. By fitting experimental data from high‐speed atomic force microscopy experiments, key rate constants and thermodynamic parameters, including free energy changes associated with oligomerization and apply the model to predict complement‐mediated lysis in liposomal vesicle‐based assays, are further quantified. The presented mechanistic framework may serve as a basis for optimizing antibody engineering and pharmacokinetic/pharmacodynamic modeling in the context of immunotherapies exploiting the CCP.https://doi.org/10.1002/smsc.202500149C1classical complement pathwaycomplement mediatedIgG hexamersIgG oligomerizationIgG subclasses
spellingShingle Jürgen Strasser
Nikolaus Frischauf
Lukas Schustereder
Andreas Karner
Sieto Bosgra
Aran F. Labrijn
Frank J. Beurskens
Johannes Preiner
A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement Binding
Small Science
C1
classical complement pathway
complement mediated
IgG hexamers
IgG oligomerization
IgG subclasses
title A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement Binding
title_full A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement Binding
title_fullStr A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement Binding
title_full_unstemmed A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement Binding
title_short A Kinetic Model of Antigen‐Dependent IgG Oligomerization and Complement Binding
title_sort kinetic model of antigen dependent igg oligomerization and complement binding
topic C1
classical complement pathway
complement mediated
IgG hexamers
IgG oligomerization
IgG subclasses
url https://doi.org/10.1002/smsc.202500149
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