Case Study: Validation of a High-Sensitivity Flow Cytometry Assay to Monitor B Cell Aplasia in Clinical Trials

October 20, 2026

Explore CellCarta’s fit-for-purpose evaluation of a high-sensitivity flow cytometry assay for B-cell enumeration in B-cell depleting therapy trials.

The challenge: During depletion, B-cell counts reach incredibly low levels. The smallest variations can have a disproportionate impact on the accuracy of results.

Standard TBNK kits (with a benchmark LLOQ of 5 cells/uL) may lack the required sensitivity and rely solely on CD19 for B cell identification, limiting their resolution beyond total CD19+ cells. This highlights a major gap in the field: a highly sensitive B cell enumeration assay is needed.

Inside the case study: The complete data on panel design and assessment of a high-sensitivity B-cell enumeration assay.

1. Highlights, strategy, evaluation and key results
2. Marker breakdown: what we included, and how our additional markers improved detection and specificity
3. Sensitivity data: B-cell Lower Limit of Quantitation well below benchmarks
4. Sample stability data: how long samples can reliably be measured for whole blood and depleted samples
5. What it means for autoimmune programs: how high sensitivity B cell enumeration contributes to BCDT programs

Inside the data: Key takeaways from assay validation.

• 50X lower reported B-cell LLOQ: 0.1 cells/µL for the assay versus a standard TBNK panel’s 5 cells/µL
• CD19 + CD20 dual-marker B-cell identification: Designed to improve B-cell resolution for therapeutics targeting B-cells
• 9 markers: Designed to improve B-cell resolution for therapeutics targeting B-cells