Summary. Three different separation methods, all using centrifugation, are routinely used to prepare therapeutic platelet concentrates from human donor blood. Platelet concentrates derived from platelet-rich plasma (PRP-PC), buffy coat (BC-PC) and apheresis (AP-PC) were investigated at the end of production, and over an 8 d storage period. Change in platelet surface markers were measured by flow cytometry, using fluorescein-conjugated antibodies to fibrinogen, P-selectin (CD62P), GPIIb-IIIa (CD41), GPIba (CD42b) and GPV (CD42d), and fluorescein-conjugated Annexin V was used to measure expression of anionic phospholipid.All concentrates showed some changes during preparation but PRP-PC underwent the greatest changes with significantly higher levels of P-selectin (P < 0 . 001) and bound Annexin V (P ¼ 0 . 001) than AP-PC or BC-PC, and lower levels of GPIba (P ¼ 0 . 002) and GPV (P < 0 . 001). These changes were attributable to component separation rather than venesection. These markers all continued to change on storage with a strong positive correlation between the changes seen during production and those after 5 d storage. PRP-PC continued to show the greatest changes whereas BC-PC showed the least. Fibrinogen was bound to 40-50% of platelets in all preparations and this did not alter significantly on storage whereas total expression of GPIIb-IIIa remained unchanged throughout.There was no evidence that the platelet surface changes were thrombin-mediated and leucocyte depletion of BP-PC by filtration had no effect on the changes. It is proposed that the deterioration of platelet concentrates during storage may be related to activation occurring during preparation. 'Whole blood' flow cytometry using a panel of fluoresceinlabelled reagents provides an informative method for evaluating platelet concentrates.

These data suggest that the quality of these components may be improved by storage in AS-7 compared with SAGM.

We have carried out a study to determine the effect of high-efficiency pre-storage leucodepletion by filtration upon the red-cell storage parameters potassium, sodium and glucose after y-irradiation to 34.5 Gy.The transfusion of viable T-cells from donor blood products can lead to engraftment and transfusion-associated graft-versus-host disease. This rare but usually fatal complication can be prevented by yirradiation of the blood product to a minimum of 25 Gy to prevent T-cell mitosis and engraftment [I]. A side-effect of y-irradiation is an increase of potassium leakage from red cells which occurs during storage. This phenomenon is of particular importance when the transfusion is of a large volume and given to a neonate or to a patient with a pre-existing renal problem or hyperkalaemia. However, the cause of accelerated potassium leakage remains uncertain. It has been postulated that the mechanism may be indirect, involving granulocyte proteases.To test this hypothesis, 19 units of CPD-A1 red cells were produced by centrifugation of CPD-AI whole blood at 2,174g for 2.5 min followed by expression of platelet-rich plasma to leave the concentrated red cells. The packs were sampled (5 ml) and stored at 2 4°C for 48 h at which time 10 units were leucodepleted using Pall BPF-4 filters. Mean residual leucocytes in the filtered and control non-filtered units were 3 . 7~ 105/unit and 2 . 8 6~ lO'/unit, respectively. Filtration time was 17:03+2:32 min. All 19 units were then y-irradiated to a dosage of 34.5 Gy delivered over 7 min. All units were sampled before and after filtration (if applicable) and irradiation, followed by sampling at 3,7, 14, 21, 28, 35 and 42 days. The supernatant was removed and stored at Fig. 1. Potassium release form y-irradiated CRC. Data represent mean f 1 SD. KARCER Q 1996 S . Karger AG, Basel E-Mail kargurer karger.ch cnU L~~ L I m r I I ? A Perkins HA: Should all blood from related donors be irradiated? (editorial). Transfusion 1992;32:302-303. Rivet C, Baxter A, Rock G : Potassium levels in irradiated blood. Transfusion 1989;29: 185. Ramirez AM, Woodfield GD, Scott R, McLachlan J: High potassium levels in stored irradiated blood. Transfusion 1987;27:44+445. Walther-Wenker G . Horstman E, Muller N: Optimised red-cell concentrates for the transfusion of premature neonates (abstract FP02-P7). 26th DGTl Congr 1993. Heaton WAL: Effects of 3-5 log,, pre-storage leucocyte depletion on redcell storage and metabolism. Br J Heaniatol 1994;87:363-368. Chambers LA, Wissel M, Price N, Gunter J: Effects of filtration on potassium levels in previously irradiated and stored CPDA-I packed cells. Transfusion 1993;33(suppl.):335S36

BACKGROUND: Platelet concentrates (PCs) suspended in more than 90% additive solution (AS) are recommended for patients with reactions to platelets stored in plasma. Next-generation AS containing glucose and bicarbonate might enable storage of these PCs for longer than those in current-generation AS, which was therefore evaluated in this study. ABBREVIATIONS: BC(s) = buffy coat(s); HSR = hypotonic shock response; PAS(s) = platelet additive solution(s); PC(s) = platelet concentrate(s); PMP(s) = platelet-derived microparticle(s). From 1 NHS Blood and Transplant,