Antigen Density Quantification Controls
QuantCytes carry defined numbers of antigen molecules per cell, so you can convert fluorescence into antibody binding capacity and track expression levels consistently across runs.
Measuring antigen density by flow cytometry
Antigen density is the number of target molecules on a cell, and quantifying it by flow cytometry means converting fluorescence intensity into antibodies bound per cell. QuantCytes controls provide multiple defined antigen density levels that generate distinct, reproducible fluorescence, giving a standard curve for direct measurement of antibody binding capacity without needing the fluorophore-to-antibody ratio.
Related: quantitation controls and immunophenotyping controls.
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QuantCytes™ CD19
Slingshot Bio Reagent
QuantCytes™ CD19 quantitation controls are precision engineered lyophilized cell mimics designed to quantify CD19 molecules per cell and support consistent expression benchmarking across research and development workflows. These synthetic cells feature the CD19 biomarker with scatter properties resembling human lymphocytes, enabling realistic assay performance and reliable calibration. Each kit provides four defined populations representing negative, low, medium and high CD19 expression levels. Each positive population contains a known number of CD19 molecules, generating distinct fluorescence intensities and antigen density levels for accurate quantification. Using a PE or APC conjugated CD19 antibody, these controls allow direct measurement of antibody binding capacity without requiring knowledge of fluorophore molecules per antibody. Incorporating the measured intensities into the provided Antigen Density Calculator enables generation of a signal to antigen standard curve that can be used to quantify antigen densities on cell targets with the same instrumentation and antibody. As with all QuantCytes™ products, QuantCytes™ CD19 quantitation controls are safe to use in any environment, contain no biohazardous material and require no special disposal. ResourcesTechnical Data Sheet Certificate of Analysis Antigen Density Calculator Poster: Enhancing Immunophenotyping Standardization in Clinical Labs with Quantitative BCMA or CD19 Cell Mimics
Antigen density FAQs
What is antigen density in flow cytometry?
Antigen density is the number of target molecules expressed on a cell. In flow cytometry it is estimated by relating a cell's fluorescence to a reference with known molecule counts, then expressing the result as antibodies bound per cell.
How do you measure antibody binding capacity?
Run a set of controls with defined antigen density levels, build a standard curve from their fluorescence, and read your sample against it. QuantCytes provide those defined levels as stable cell mimics.
Why use cell mimics instead of donor cells for antigen quantification?
Donor cells vary in expression from sample to sample, so they do not give a stable reference. Engineered controls hold defined antigen densities, so the standard curve is the same every run.
Ready to quantify antigen density with confidence?
Talk to our team about building a standard curve for antibody binding capacity with QuantCytes.