Effect of holding buffy coats 4 or 18 hours before preparing pooled filtered PLT concentrates in plasma

Filtered PLT concentrates (PCs) were prepared in plasma pooling three (for children) or six buffy coats (BCs; for adults) after holding them a maximum of 4 hours (blood bags collected in the afternoon) or 18 hours (blood bags collected in the morning).

With flow cytometry, PCs prepared after holding BCs 4 or 18 hours were compared. BCs removed from whole-blood donations in quadruple bag packs ("top-top") were held 4 or 18 hours before pooling them with a sterile connecting device. After the BCs were centrifuged, the supernatant was transferred through a BC filter (Autostop, Pall Medical) to a CLX bag. Samples for analysis were collected from the whole-blood bag, BCs, and PCs immediately after preparation and after 1, 3, 5, and 7 days of storage on a flat-bed agitator at 22 +/- 2 degrees C. The main PLT membrane glycoproteins (GPs, IIb-IIIa, IV, and Ibalpha), some of their ligands (fibrinogen, fibronectin, and VWF), activation-dependent antigens (CD62P and CD63), and procoagulant activity markers (annexin V and bound coagulation FV-Va) have been studied.

In the 12 PCs (six pools of 3 units each group) studied, a minor increase in activation markers during preparation was observed. During the storage, a significant increase in the expression of GPIIb-IIIa, CD62P, CD63, annexin V, and FVa was measured. After 5 days of storage, only the percentage of PLTs with bound fibrinogen was significantly greater in PCs prepared after holding BCs for 4 hours.

In PCs prepared after holding BCs 4 or 18 hours before pooling and filtering, only a minor significant difference in the percentage of PLTs with bound fibrinogen was found after 5 days of storage. This difference is probably of little, if any, transfusional significance.