Effect of Prestorage Leukocyte Reduction on Proteins of Platelets Obtained by Apheresis

Abstract

The effect of prestorage leukocyte reduction was evaluated on platelet concentrates (PCs) obtained by apheresis using the ‘surge’ technique. Two hours after collection, the PCs were divided into 2 equal units. One unit was filtered through a Sepacell PL-10a®, producing a filtered PC (FPC). The second unit constituted a non-filtered PC (NFPC). FPCs and NFPCs were stored at room temperature in 1,400-ml CLX® bags on a horizontal agitator up to 7 days. We analyzed platelet samples obtained during storage from NFPCs and FPCs at days 1,3 and 7. The expression of membrane glycoproteins (GP)Ib and GPIIb/ IIIa (assessed by flow cytometry), platelet response to thrombin and ristocetin (aggregometry) and global platelet protein pattern (studied by high-resolution two-dimensional gel electrophoresis) remained stable over the 7 days of storage in NFPCs as well as in FPCs. However, in both preparations, the expression of GMP-140 (flow cytometry) progressively increased during storage. Our in vitro study indicates that early leukocyte reduction by filtration of apheresis PCs does not induce modifications in platelet GPs and protein patterns.

The quality of platelets after storage for 7 days

“…This suggests that as the age of PCs increases, the capacity of platelets to become activated in response to thrombin is reduced. It is therefore not surprising that aggregation in response to low doses (0Á05 U mL À1 ) of thrombin is reduced to 80% of initial values at day 7 (Sarraj-Reguieg et al, 1993). There is also a 50% loss of GPV during storage of PCs for 8 days (Metcalfe et al, 1997), which is not unexpected because GPV exists as a complex with GPIb.…”

“…When platelets become activated, there is a conformational change in GPIIb/IIIa (CD41/ CD61), enabling binding of fibrinogen and vWF, a key mechanism in promoting platelet-platelet aggregation. Most studies have shown that expression of GPIIb/IIIa does not alter throughout storage of PCs to days 7-9 (Sarraj-Reguieg et al, 1993;Metcalfe et al, 1997;Ferrer et al, 2000a,b), is similar in PRP, BC or apheresis PC (Metcalfe et al, 1997) and is not influenced by leucodepletion (Boomgaard et al, 1994c(Boomgaard et al, , 1995. However, this provides little information on whether there are any changes in the function of this receptor, i.e.…”

“…GPIb (CD42b) is a platelet receptor for von Willebrand factor (vWF), which under conditions of high shear rate facilitates adhesion of platelets to the subendothelium through the interaction of vWF and collagen. Some studies report little change in the percentage of platelets expressing GPIb during storage of PCs for 7-9 days (Sarraj-Reguieg et al, 1993;Boomgaard et al, 1995;Ferrer et al, 2000a), whilst others show a decrease of 5-30% over this time period (George et al, 1988;Garcia et al, 1992;Metcalfe et al, 1997;Ferrer et al, 2000b). Loss of GPIb expression during storage of PCs is likely to be due to proteolytic cleavage, because levels of glycocalicin in the supernatant also increase (Michelson et al, 1988).…”

“…Loss of GPIb expression during storage of PCs is likely to be due to proteolytic cleavage, because levels of glycocalicin in the supernatant also increase (Michelson et al, 1988). The ability of platelets to agglutinate in response to ristocetin (a measure of platelet GPIb and plasma vWF) tends to parallel the expression of GPIb during storage of PCs throughout 7/8 days (Garcia et al, 1992;Sarraj-Reguieg et al, 1993). GPIb also contains moderate and high-affinity-binding sites for thrombin.…”

Human blood platelet protein map established by two‐dimensional polyacrylamide gel electrophoresis

“…Sixma et al [8] identified glycoproteins from the membrane of platelets. Sarray-Reguieg et al [9] and Snyder et al [lo] analyzed the protein modifications during storage of platelets. Assakawa et al [ll] explored the usefulness of 2-D PAGE for the study of genetic variations of platelet proteins.…”