A High-Throughput Multiplex Assay for Protein Analysis
Cytometric Bead Array (CBA) is a powerful flow cytometry-based technique that enables the simultaneous quantification of multiple soluble proteins within a single sample. This innovative approach combines the features of immunoassays with the multiplexing capabilities of flow cytometry, allowing researchers to measure cytokines, chemokines, growth factors, and other analytes with high sensitivity and accuracy. Unlike traditional ELISA, which measures a single analyte per well, CBA can identify over 30 targets in a small sample volume, making it invaluable for immunology research, biomarker discovery, and clinical diagnostics.
The CBA system utilizes a set of microspheres (typically 5-8 micrometers in diameter) that are internally dyed with specific fluorescent intensities, creating a unique spectral signature for each bead population. Each bead set is coated with specific capture antibodies for the target protein. When incubated with a test sample, the beads capture their respective analytes, which are then identified using a mixture of detection antibodies conjugated to phycoerythrin (PE) or other fluorescent dyes. The flow cytometer identifies each bead population based on its spectral code and simultaneously quantifies the PE fluorescence intensity, which correlates with the analyte concentration.
Immunology Studies
CBA is widely used to profile cytokine secretion patterns (Th1/Th2/Th17 responses) from stimulated immune cells. Researchers can simultaneously quantify IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, and other cytokines to delineate immune responses to infections, vaccinations, or autoimmune stimuli.
Biomarker Discovery
In cancer and inflammatory diseases, CBA facilitates the identification of diagnostic or prognostic biomarker panels. For instance, the simultaneous measurement of VEGF, IL-8, and MMPs in patient serum can reveal protein markers associated with disease.
Drug Development
Pharmaceutical companies utilize CBA to monitor pharmacodynamic responses to therapies, such as changes in inflammatory cytokines following the administration of biologic drugs.
Clinical Diagnostics
Commercial CBA kits (e.g., BD CBA Human Inflammation Kit) have been approved by the FDA for measuring cytokines in patient samples, aiding in the management of sepsis, cytokine release syndrome, and other immune system-related conditions.