Homogeneous Proximity Assay for Antibody C1q Binding

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Solution Overview

Problem

Existing methods for determining the binding of antibodies to complement component 1q (C1q) are not fully satisfactory due to geometrical constraints in the hexameric IgG/C1q binding model, leading to unpredictable and non-reproducible results, necessitating a more efficient and reproducible method for assessing this binding.

Innovation Solution

A novel in vitro method using a Homogeneous Proximity Assay (HPA) involving a biotinylated anti-Fab ligand, streptavidin, and C1q, where the binding of the tested antibody to C1q is measured through a signal indicative of the HPA, allowing for the assessment of antibody-mediated complement-dependent cytotoxicity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If solid phase methods (ELISA or SPR) are used to cluster IgG antibodies to bind C1q, then the binding measurement can be performed, but the results are not reproducible and require normalization due to geometrical constraints in the hexameric IgG/C1q binding model

Engineering Contradiction:

Improvebinding measurement accuracyVSAvoidresult reproducibility

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces Protein A as an intermediary molecule that mediates the clustering of IgG antibodies. Protein A binds to the Fc region of IgG antibodies and presents them in a controlled orientation and density on magnetic beads, creating optimal clusters for C1q binding. This intermediary approach resolves the geometrical constraints problem by providing a standardized platform that ensures reproducible IgG clustering, eliminating the need for normalization and improving result reliability while maintaining measurement precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If antibodies are randomly immobilized on the surface (passive coating), then the assay can be performed, but the binding affinity to C1q cannot be optimized due to unpredictable clustering

Engineering Contradiction:

Improveassay simplicityVSAvoidbinding affinity

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-coating magnetic beads with Protein A before adding IgG antibodies. This pre-prepared Protein A layer is optimized to present antibodies in the correct orientation and density, ensuring that when antibodies are added, they automatically form clusters with optimal geometry for C1q binding. This preliminary preparation step maintains assay simplicity while dramatically improving binding affinity measurement precision, as the clustering geometry is predetermined rather than random.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If antibodies are indirectly immobilized using Protein L, then the assay can be performed, but the results still require normalization due to inconsistent clustering

Engineering Contradiction:

Improveassay flexibilityVSAvoiddata consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the key parameter of protein coating from Protein L to Protein A. Protein A has different binding characteristics to IgG Fc regions compared to Protein L, providing more consistent and predictable antibody orientation and clustering. This parameter change (switching the coating protein) maintains assay flexibility and adaptability while significantly improving data consistency and reliability, as Protein A creates more uniform antibody clusters that reduce variability between experiments.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method provides a reproducible and efficient means to determine the binding of antibodies to C1q, offering improved accuracy and reliability in assessing the ability of antibodies to mediate CDC, as demonstrated by specific HTRF and ALPHA assay results.

Implementation Method 1

a biotinylated anti-Fab ligand, said biotinylated anti-Fab ligand being able to bind the Fab region of the tested antibody

Methodology Applied

Scientific EffectAntigen-antibody binding:

Implementation Method 2

a streptavidin directly or indirectly labelled with the first member of a pair of HPA (Homogeneous Proximity Assay) partners

Methodology Applied

Scientific EffectBiotin-streptavidin binding:

Implementation Method 3

a streptavidin directly or indirectly labelled with the first member of a pair of HPA (Homogeneous Proximity Assay) partners, and a C1q directly or indirectly labelled with the second member of a pair of HPA partners; b) Measuring the HPA signal in the measurement medium

Methodology Applied

Scientific EffectHomogeneous Proximity Assay signal:

Data Source

PatentUS20240361334A1Method for determining the binding of an antibody to the complement component iq (CIQ)

Publication Date: 2024.10.31 CISBIO BIOASSAYS

AI summary

The invention relates to a novel method for determining the binding of an antibody to the complement component 1q (C1q). The process according to the invention makes it possible to measure the binding of an antibody to the C1q in a Homogeneous Proximity Assay (HAS).