This month’s focus is on determining receptor density using flow cytometry.
The number of late-stage studied antibody therapeutics has increased from 26 in 2010 to over 200 this year (Crescioli et al., 2026). Of the 13 antibodies, antibody-based molecules, and antibody mimetic biologics approved in 2025, 7 target cell surface receptors (Strohl, 2026). Thus, receptor density is a critical measure for this growing field.
HOW-TO GUIDE
How do I determine the antibody binding capacity (ABC) of my cell?
This highly demanding application can be a quantitative measure with a few quick steps and the matching Quantum™ Simply Cellular® (QSC) kit. QSC kits have one blank and four additional populations with increasing amounts of Fc-specific capture antibody.
Using your antibody, QSC beads can standardize the fluorescence intensity units because each lot of QSC have calibrated antibody binding capacities (ABCs) that are prepopulated in your QuickCal® Excel® Template. In brief, the procedure includes the following steps:
Identify the host for your fluorescently conjugated antibody that recognizes your receptor of interest & purchase the corresponding QSC kit (Bangs Labs offers anti-mouse IgG, anti-human IgG, & anti-rat IgG kits).
Add a saturating amount of your antibody to each of the 4 bead populations and your experimental cell samples. Do not add antibody to the blank bead population.
Analyze the microspheres and your labeled cells on the flow cytometer using the settings for your cell type and fluorophore.
Measure the mean fluorescence intensity of each of the 4 QSC populations, the QSC blank bead population, unlabeled cells, and labeled experimental samples.
Use your lot-specific QuickCal® Excel® template to perform regression analysis that converts the MFI of your cellular sample into the number of bound antibodies.
Just remember “SAME” for best results
Same type of suspending solution since fluorophore emissions can depend on pH and ionic strength of the media
Same instrument
Same instrument settings
Same day
For more information, reach out to us at info@bangslabs.com or call us at 317.570.7020 or 800.387.0672 (US & Canada).
RECENT PUBLICATIONS USING QUANTUM™ SIMPLY CELLULAR®
Bucher, P., Brückner, N., Kortendieck, J., Grimm, M., Schleicher, J. T., Bartels, K., ... & Leibold, J. (2026). CAR-adapted PIK3CD base editing enhances T cell anti-tumor potency. Nature Cancer, 7(2), 368-383. https://doi.org/10.1038/s43018-025-01099-7
Current prototypic 28z CARs are prone to T cell exhaustion, and BBz-based CARs have slower effector function due to a slower T cell expansion. To reverse these deficiencies, the authors used base editing to find advantageous alterations in PI3Kdelta that can fine-tune the signal transductions of 28z- and BBz-based CARs. QSC anti-Mouse IgG kits were used to measure the surface levels of antigens for their studies.
Wu, WH., Sivaneri, N., Akin, E. et al. CD98hc-targeted antibody shuttles for central nervous system delivery with broad cross-species reactivity. Nat. Biomed. Eng (2026). https://doi.org/10.1038/s41551-026-01718-3
Getting bispecific antibodies across the blood-brain barrier (BBB) can increase their therapeutic potential, but animals commonly used in pre-clinical testing do not have cross reactivity with human BBB penetrating antibodies. The authors used iterative mutagenesis and library optimization to identify BBB penetrating antibodies that have similar affinity to human, mouse and cynomolgus monkey brain endothelial cell receptors. Quantum™ Simply Cellular® anti-Human IgG kit was used to determine the density of the antibody receptor on mouse brain endothelial cells.
Each QSC kit includes 5 populations of beads, 1 blank and 4 with increasing concentrations of sites for binding your monoclonal antibody of choice. Create a standard curve to extrapolate the number of binding sites are found on your cells.
Quantify your test samples based on a standard curve created by one of our Quantum MESF kits. Each has five populations, 1 blank and 4 with increasing fluorescent intensity. Our QuickCal® template is a lot-specific, pre-populated worksheet to create a calibration curve.
