Fig. 1

A, B Platelet concentrate units (PC) are prepared from anticoagulated whole blood mainly with buffy coat method or the PRP method. For the first method the whole blood unit is centrifuged and four buffy coat units plus one plasma unit (4 donors) are mixed together (final volume around 300 mL). Following a second centrifugation round the PC is leukocyte depleted and stored. For the PRP method, 4 or 5 PC are pooled to obtain a therapeutic unit of approximately 200 mL. Leukocyte depletion and storage are the following steps. A Apheresis platelet machines can extract directly PC from donors (less frequent method used—not shown in A)