The effects of apheresis, storage time, and leukofiltration on microparticle formation in apheresis platelet products.

Although platelet microparticles (PMPs) were the most abundant micoparticles (MPs) in platelet (PLT) products, other MPs and their parental cells can also be brought into the plasma during PLT apheresis. However, the effects of PLT apheresis, storage time, and leukofiltration on these MPs remain largely unclear. Apheresis PLTs with or without leukofiltration were stored in 22 ± 2 °C for 5 days. PLT-poor plasma (PPP) was generated by centrifugation of donor blood or PLT products at 2500 × g for 15 minutes on the point day. PPP was labeled with CD41a (PLT-derived MP, PMP), CD235 (red blood cell-derived MP, RMP), CD45 (leukocyte-derived MP, LMP), CD14 (monocyte-derived MP, MMP), and CD144 (endothelial cell-derived MP, EMP), and then measured by flow cytometry. Higher-level TMPs (total microparticles) and PMPs, but lower-level RMPs, LMPs, and MMPs were detected in fresh PLTs on the day of collection compared with those before collection. During storage, TMP, PMP, and RMP counts were significantly higher on Day 3 and Day 5, but MMP and LMP counts were only marginally higher on Day 3 in PLT supernatants. There were no significant differences in MP levels in PLTs with or without leukofiltration. MP formation was affected by the apheresis procedure. RMPs, LMPs and MMPs were lower after PLT apheresis. During storage, TMPs, PMPs, RMPs, LMPs, and MMPs were found to be higher in PLT supernatants. Leukofiltration exerted no significant effect on all MPs in PLT products.