DRIFT ANALYSIS APPROACH TO INVESTIGATE THE EFFECT OF SPECIMEN AGE AND PREPARED SAMPLE AGE ON THE STABILITY OF LYMPHOCYTE SUBSETS
Elena Afonina,1 Robert Magari,2 Jin Zhang,1 Samantha Bauchiero,1 Violetta Headley,1 and Liliana Tejidor2
1Life Science Beckman Coulter, Miami, FL
2Diagnostics Beckman Coulter, Miami, FL
A novel statistical approach was used to assess the stability of CD3+/CD4+, CD3+/CD8+, CD3−/CD56+, CD19+, and CD3+ lymphocyte subsets in CYTO-STAT® tetraCHROME™ stained samples and analyzed on FC 500™ or Navios™** (**Pending clearance by the United States Food and Drug Administration; not yet available for in vitro diagnostic use within the USA) flow cytometers. Approximately, 30 normal and clinical specimens were included in the data analysis for each study. Among them ≥ 50% had CD4+ absolute counts lower than 500 cells/ul. Specimens were stored at room temperature for the following time periods: fresh (≤8 h), 24, 48, and 72 h post-venipuncture. Additionally, samples at each time point were prepared and refrigerated up to 48 h prior to analysis. Data were modeled as linear functions of specimen age and prepared time, while sample-to-sample variability was considered as the random component of the model. The drift (change) from the reference point (0 (specimen age) to 0 (prepared sample age)) for each analyte was estimated from the model. Drifts were estimated at different points along with their 95% confidence intervals. The following graphs illustrate specimen and prepared sample stability drift for samples analyzed on Navios™ flow cytometer (Figs. 1 and 2). The most significant contributor to overall specimen stability was specimen aging in whole blood. In contrast, prepared sample storage had less impact on the cell loss. In conclusion, the derived models provide a robust method for prediction of the drift at different time points within the tested range.