Analytical performance of an automated volumetric flow cytometer for quantitation of T, B and natural killer lymphocytes

Quantitation of lymphocyte subsets (B cells, T cells, CD4 and CD8 T cells and NK cells) classically relies on quantitation of lymphocytes and immunophenotyping by flow cytometry. AQUIOS CL (Beckman Coulter) is a fully automated system that performs an onboard volumetric cell count, automatically processes the sample (staining, lysing and fixation) and analyzes the results. We compared AQUIOS CL to a dual-platform analysis and evaluated analytical performance.

We evaluated precision, sample stability, inter-sample carryover, linearity and interpanel consistency. AQUIOS CL was compared to a dual-platform method (Sysmex XE-5000 and BD FACSCanto-II). A total of 113 patient samples were included: 45 from posttransplant patients, 44 from children and 24 random routine samples. The degree of automation was scored through the need of manual revisions triggered by AQUIOS CL run notifications and run flags.

Intrarun and interrun variability was <9.1% with dedicated control material and <32.1% with patient samples. Relative values of lymphocyte subsets could be determined up to 48 h after venipuncture when the sample was kept at room temperature. There was no carryover and good linearity. Interpanel consistency was 3.3% for relative values and 9.4% for absolute values. Method comparison showed good analytical correlation between AQUIOS CL and a dual-platform method. Thirty-five percent of the samples triggered a run notification. In 74% of these samples, the results could be accepted without intervention, so in 26% of all samples, an unnecessary notification was generated.

AQUIOS CL allows for reliable fully automated immunophenotyping of lymphocyte subset quantitation. Gating algorithms could be further improved.