(P-IS-7) Stability Evaluation of Pooled Platelets on the BD FACSLyric Flow Cytometer using the BD Leucocount Kit

Background/Case Studies: The BD Leucocount kit (BD Life Sciences, San Jose, CA) measures residual white blood cells (rWBC) in leukoreduced platelet (PLT) and red blood cell (RBC) products. The kit contains Leucocount reagent containing propidium iodide, a fluorescent nucleic acid dye, and Trucount tubes to determine absolute rWBC count using flow cytometry. The stability of rWBC measurement in pooled platelets using the BD Leucocount kit at different time points was evaluated.

Study

Design/Methods: Samples from thirty (30) whole blood-derived platelet concentrate (PC) pools were spiked with autologous WBC at 3 WBC levels (2 levels/pool), ranging from >1 to < 350 WBC/µL (N=20/level). Stained samples were prepared using the BD Leucocount kit, according to manufacturer’s IFU, at 7 pooled product storage time points of < 6 hours (T0 reference time point), and 24 through 48 hours (T1-T7 time points). Samples were stored at RT at time points of < 30 min to < 24 hr and analyzed on the FACSLyric flow cytometer.

Results/Findings: rWBC results for each time point (T1 to T7) were compared to results of the reference time point (T0). Data are presented in Table 1. Length of time between completion of platelet pooling and immediately prior to sample staining is expressed as age of product (AOP), and time between completion of sample staining and sample acquisition on the FACSLyric is expressed as age of stain (AOS). No significant bias was determined for each time point (acceptance criteria of ± 20%).

Conclusions: Results demonstrate that pooled PC with 24-hour age of pooling and 24- hour age of stain was stable compared to the reference time point (T0); and pooled platelets with 48-hour age of pooling and 2-hour age of stain were also stable compared to time zero. Data obtained from this study support use of the BD Leucocount kit for rWBC measurement in pooled platelet product.

Importance of research: Flow cytometry is one method used to count rWBC in leukoreduced red cell and platelet products. The BD Leucocount kit is a flow cytometric method for the preparation and QC testing of samples from LR products. The study reported on in this submission characterized the stability of samples obtained from pooled whole blood-derived platelet concentrates using the BD Leucocount kit for the flow cytometric determination of absolute cell counts of rWBC.