Simplifying CD19 CAR Detection: A Bright Single-Step Solution for Flow Cytometry 2259753

Abstract Introduction Accurate flow cytometric detection of CD19 CAR-expressing cells is critical across CAR-T cell discovery and translational research workflows. However, variability in surface CD19 CAR protein expression presents challenges in reliably identifying CAR+ cells. Additionally, detection using recombinant CD19 protein is hindered by its instability in soluble form. Methods To address these limitations, BD® has developed a novel, bright, and stable one-step CD19 CAR Detection Reagent, available in multiple fluorochrome formats to support diverse panel designs and instrument configurations. Results We demonstrate that this reagent specifically stains CD19 CAR-expressing CHO cells, Jurkat CAR-T cells, and primary human CD19 CAR-T cells. Furthermore, it performs effectively in lysed whole blood, multi-color panels, and workflows involving intracellular staining. Notably, CAR-T cells spiked into donor PBMCs were detected at frequencies as low as < 0.04% of live cells, highlighting its potential utility in studies of CAR-T cell persistence. Minimal background staining was observed in CAR-negative and mismatched CAR populations, and low-expressing CAR cells (CARlo) were distinguishable from negative cells Conclusion Overall, these findings highlight the BD® CD19 CAR Detection Reagent as a robust solution for overcoming key challenges in CD19 CAR+ cell detection, enabling progressive CAR-T cell research. Funding Source n/a Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)