Lumit® C1q Binding Assay
Evaluate C1q-antibody binding to assess the initiation of the complement-dependent cytotoxicity pathway
- Improved Immunoassay Format: ELISA alternative
- Saves Time: Reduce hands-on steps with a simple, no-wash protocol
- Better Data: No immobilization to plates, beads or other surfaces required
- Results in as little as 60 minutes
Catalog Number:
Size
Catalog Number: CS3695A04
The Ideal Assay to Complement Your Antibody Development Efforts
The Fc region of monoclonal antibodies mediate several effector functions, including complement-dependent cytotoxicity (CDC), through activation of the classical complement pathway. C1q binding to the Fc region is the critical first step in activating this pathway. By quantifying Fc-C1q binding, antibody developers can precisely profile C1q-antibody interactions, predict complement activation kinetics, and accelerate therapeutic antibody selection to ensure both efficacy and safety in therapeutic applications.
Traditional methods to measure C1q binding face several limitations:
- Time-consuming incubation steps
- Highly variable fluorescent readouts
- Low throughput assay set-ups
What does using the Lumit® C1q Binding Assay mean for you?
- Get simple, reliable surrogate measurement of CDC potential in under two hours
- Analyze multiple antibody isotypes and fine-tune your Fc engineering efforts and select promising candidates quickly
- Balance efficacy with safety: achieve sufficient complement activation while minimizing off-target toxicity
- Run your samples in a high-throughput and automation friendly design
How Does the Assay Work?
Principle of the Lumit® C1q Binding Assay: The assay provides a quantitative readout of C1q binding to antibody Fc as a proxy for classical complement engagement potential. In a homogeneous, solution-phase format, a biotinylated anti-human IgG Fab is pre-complexed with streptavidin–SmBiT to multivalently capture IgG and induce Fc clustering. C1q–LgBiT is then added; when C1q binds the clustered Fc domains, LgBiT and SmBiT are brought into proximity to reconstitute active NanoBiT® luciferase, producing a luminescent signal proportional to the amount of C1q-bound antibody.
What Is the Assay Workflow?
Lumit® C1q Binding Assay design:
- Biotinylated anti-human IgG Fab is pre-complexed with genetically fused Streptavidin-SmBiT, which multivalently captures IgG in solution and induces Fc clustering.
- Upon C1q-LgBiT addition and IgG binding, SmBiT and LgBiT are brought together, reconstituting active NanoBiT® luciferase.
- The luminescent signal is proportional to C1q bound to the antibody, enabling quantification of antibody-C1q interactions.
Accurately Detect Binding Differences Across Antibody Variants
Lumit® C1q binding assay is suited for distinguishing antibody specificity and sensitivity. The Lumit® C1q Binding Assay was tested against a panel of Rituximab variants that included different IgG isotypes as well as fucoslyation and glycosylation modifications. The binding profiles align with published literature.
Compare for yourself: Impact of structural modifications of IgG antibodies on effector functions.
| Rituximab | Non-fucosylated Rituximab | Non-Glycosylated Rituximab | Rituximab IgG2 isotype | Rituximab IgG3 isotype | Rituximab IgG4 isotype | |
| EC50 (nM) | 9.192 | 8.790 | 5278040 | 57.47 | 2.455 | 38534 |
Interested in other Fc effector functions like ADCC or ADCP?
We offer a wide range of Lumit® binding assays to measure interactions between Fc receptors and antibodies.Protocols
No protocols available
Specifications
Catalog Number:
What's in the box?
| Item | Part # | Size |
|---|---|---|
Human C1q-LgBiT |
CS3695A01 | 1 × 60μl |
Streptavidin-SmBiT |
CS3695A02 | 1 × 30μl |
Anti-human IgG Fab-Biotin |
CS3695A03 | 1 × 150μl |
Lumit® Immunoassay Dilution Buffer A, 10X |
VB201A | 1 × 10ml |
Lumit® Detection Substrate A |
VB301D | 1 × 75μl |
Resources
Featured Resource: Webinar
Lumit® Immunoassays: An Easier Faster Method for Analyte Detection
In Lumit® Immunoassays, antibodies (or other affinity reagents) are chemically labeled with the small and large subunits of NanoLuc® Luciferase, known as SmBiT and LgBiT, respectively. In the presence of an analyte, the two antibodies come into close proximity, allowing SmBiT and LgBiT to form an active enzyme and generate a bright luminescence signal.
- Use simple, add-mix-read protocols to detect a variety of analytes
- Implement existing Lumit® assays in your lab or build your own Lumit® immunoassays
- Analyze data using examples for cytokine detection, signaling pathway analysis and FcRn binding
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