The effects of leukodepletion on the generation and removal of microvesicles and prion protein in blood components.

Background: Universal leukodepletion (LD) has been implemented in the United Kingdom to reduce the risk of transfusion-transmitted variant Creutzfeldt-Jakob disease. If LD causes microvesiculation of blood cells, however, potentially infectious membrane-associated prion could reach the final products.

Study Design And Methods: We have measured microvesicles (MV) derived from red cells (RBC-MV), platelets (PLT-MV), and white blood cells (WBC-MV) and cellular prion protein (PrP(c)) in blood components produced by four whole-blood, five RBC, three PLT, and two plasma LD filters and three plateletpheresis techniques.

Variables determining blockage of WBC-depleting filters by Hb sickle cell trait donations.

Background: Sickle cell trait donations can block leukodepletion (LD) filters or fail to LD, but the variables affecting blockage are unclear.

Study Design And Methods: To identify critical variables for further study, the relationship was investigated between filter blockage and donor characteristics, processing conditions, PLT and coagulation system activation, and microvesicle formation in donations with (n = 63) and without (n = 40) sickle trait. With eight filter types whole blood was LD either at ambient temperature on Day 0 or after overnight 4 degrees C hold.

Cytokine levels as performance indicators for white blood cell reduction of platelet concentrates.

Background And Objectives: With the implementation of universal white blood cell (WBC) reduction in the UK, in-process WBC-reduction filters for pooled buffy coat (BC)-derived platelet concentrates (PCs) and apheresis methods are used routinely for the production of WBC-reduced PCs. While these strategies meet the specification for WBC reduction (< 5 x 10(6) WBCs/unit), the products from these processes may differ depending on the process employed and its performance. The aim of this study was therefore to investigate whether PCs prepared using various WBC-reduction processes are sufficiently depleted of WBCs to limit cytokine accumulation during storage and to assess if cytokine levels detected in platelet products can serve as indicators of acceptable platelet activation as a result of the WBC-reduction process.

Red cell storage lesion assessed by the levels of potassium, haemoglobin and Annexin V in supernatants.

The conventional and a new marker of global cellular lesion (Annexin V) are used to assess the processing/storage-induced changes in four types of RBC and filtered blood at 4 degrees and 22 degrees C, stored for a period of 35 days, in multi-satellite packs. It appears that mechanical trauma and presence of leucocytes and residual platelets have potential to increase levels of all markers of storage lesion, but to a variable extend. We have also provided new evidence that multi-satellite packs can be safely used for up to 35 days for small volume transfusion to sick premature infants, in a well-managed system by administering several transfusions from the same donation, hence reducing donor exposure.