Vitalant Research Institute Denver, Colorado, United States
Background/Case Studies: The isolation of white blood cells (WBCs) from peripheral blood is a crucial step in various fields, including immunology, cell therapy, and diagnostics. The buffy coat (BC) method is an established method to separate WBCs from whole blood by centrifugation and isolation of the buffy coat layer. In contrast, the leukoreduction system (LRS) chamber of the Trima device (Terumo BCT), automatically traps and removes WBCs from platelet products during apheresis procedures. The aim of this study was to compare the cellular content of these WBC sources.
Study
Design/Methods: BC products were isolated by centrifugation from 500 mL whole blood donations within 8 hrs of collection. After removal of the plasma, the buffy coat layer was carefully expressed into a satellite bag and labeled as a non-injectable product. BC products were shipped to the central lab and analyzed 1-2 days after collection. LRS chambers from routine platelet collections in 100% plasma were sealed off and removed from the disposable tubing set. The LRS chambers were drained and analyzed within 6 hrs of collection. Cells were analyzed on a hematology analyzer (Sysmex) and by flow cytometry (Becton Dickinson) using antibodies to various WBC subpopulation markers.
Results/Findings: LRS chambers were simpler to acquire and were fresher upon receipt. The LRS chamber yielded lower numbers of total WBCs, however the percentage of lymphocytes was significantly higher in the LRS chamber (70%) than in BCs (46%). In contrast, BC contained a higher percentage of neutrophils than LRS chambers (40% versus 3%, respectively). LRS chamber products had significantly lower RBC and platelet contamination. Comparison of the products by flow cytometry showed similar trends and similar percentages of CD4, CD8 and CD19 positive cells. Extra WBCs can be recovered from the Trima disposable set by draining the entire channel (averaging 1.5x10^9), if the Trima device is not set-up to perform plasma rinseback at the end of the collection procedure. Conclusions: The BC method is complex and time consuming compared to draining an LRS chamber. LRS chambers are a side product of plateletpheresis procedures using the Trima device and are readily available through most local blood collection centers. Both, the BC method and LRS chamber, are effective methods for isolating PBMCs. Depending on the downstream analysis, the LRS chamber may provide fresher PBMCs of higher purity.
Importance of research: PBMCs or WBCs are important for research as they play a crucial role in the immune system and can be used to study a wide range of diseases and disorders. The isolation method can influence what type and number of WBCs are obtained, and how readily available the cells can be. We compare here the cellular content of buffy coats and LRS chambers so researchers can decide which is the best product for their investigations.
