Differential reduction in lymphocyte and granulocyte content by removal of the buffy coat from fresh and overnight-stored blood. Comparison of manual and automated blood processing systems.

The efficiency of leukocyte removal was studied by the removal of the buffy coat layer from fresh and overnight-stored whole blood. Manual blood processing was compared with two types of automated separators: the T-ACE (Terumo) and the OPTI system (with the top-and-bottom bag, Baxter). The main characteristics of leukocyte removal were similar for the systems studied. The efficiency of leukocyte removal was consistently higher with overnight-stored blood. When the net red cell content of the buffy coat was 20-30 mL, the figures were: 70% (n = 103) vs 45% (n = 87, manual method), 78% (n = 6) vs 60% (n = 100, T-ACE) and 82% (n = 10) vs 71% (n = 20, OPTI system), respectively. The increase in the efficiency in leukocyte removal was due to a rapid increase in the efficiency of removal of granulocytes: 65% (n = 65) vs 45% (n = 57, manual method), 80% (n = 4) vs 46% (n = 83, T-ACE) and 74% (n = 9) vs 57% (n = 17, OPTI system), respectively. Processing of overnight stored blood may provide red cell concentrates with fewer contaminating leukocytes and granulocytes.