Assessing agreement between CD34 enumeration by flow cytometry and volumetric analysis.

Area of Science:

• Hematology
• Clinical Laboratory Science
• Immunophenotyping

Background:

• Accurate CD34 enumeration is vital for hematopoietic stem cell transplantation.
• Established methods require validation before replacement by new assays.
• Bland and Altman methods provide a framework for comparing measurement agreement.

Purpose of the Study:

• To compare the agreement between a dual-platform flow cytometry assay and a single-platform volumetric analysis assay for CD34 enumeration.
• To assess the reproducibility and concordance of the two methods across different cell concentration ranges.

Main Methods:

• CD34 enumeration was performed on 105 patient samples (blood or leukapheresis product).
• Comparison utilized flow cytometry (dual-platform) and volumetric analysis (single-platform).
• Agreement was evaluated using Bland and Altman analysis.

Main Results:

• Both methods exhibited poor reproducibility for CD34+ cell counts below approximately 9 cells/mm3.
• For counts above 29 cells/mm3, volumetric analysis yielded values of 73-80% compared to flow cytometry.
• A significant difference was observed between the single and dual platform assays at higher cell concentrations.

Conclusions:

• The volumetric analysis assay shows potential discrepancies compared to the established flow cytometry method, particularly at higher CD34+ cell concentrations.
• Poor reproducibility at low cell counts affects both methods.
• Technical pitfalls may contribute to the observed differences, necessitating further investigation.