Leucoreduced platelet concentrates in additive solution: an evaluation of filters and storage containers

Buffy coat (BC) pooling sets are integrated systems, consisting of a pooling bag, a filter and a platelet storage container, for the production of leucoreduced platelet concentrates (LR-PCs) from pooled BCs. It was our aim to compare various pooling sets that are currently marketed.

LR-PCs were made by pooling five BCs and adding 250 g of PAS-II. In study I, filters were compared: four BC pools (of five BCs each) were mixed and divided, and after centrifugation the platelet-rich supernatant (PRS) was expressed through one of the following filters: CLX-5, BioP-plus, Autostop or Imugard. In study II, storage containers were compared: five LR-PCs were mixed and divided over the following storage containers: 1300-ml PL-2410, 1000-ml and 1500-ml polyolefin, 1500-ml CLX or 1000-ml DnDP-PVC. These LR-PCs were stored for 9 days with sampling performed on days 1, 2, 5, 7 and 9. We required that the pH remained between 6.8 and 7.4, and that the swirling effect was present at the end of the storage period.

All filters gave LR-PCs that contained uniformly < 1 x 106 leucocytes (n = 12 experiments) with a recovery of, on average, 70% of the platelets originally present in the BC pools, except for the BioP-plus filter, which had a recovery of 43 +/- 10%. The 1500-ml CLX bag had, in two of nine cases, a pH < 6.8 on day 5 of storage, while the other storage containers were able to maintain a pH of > 6.8 until day 9. With the CLX container, the oxygen level remained adequate until day 9, but low glucose, high lactate and high lactate dehydrogenase (LDH) levels suggested high platelet metabolism and/or activation.

BC pooling sets have various benefits, such as less welding, resulting in a lower work-load, but not all combinations of filters and storage containers tested were suitable. Therefore, validation prior to routine use in a blood centre is necessary.