Characteristics of the specific removal of lymphocytes and granulocytes from whole blood in an automated bottom-and-top processing system.

Characteristics of lymphocyte and granulocyte removal were studied during processing of fresh and overnight-stored human blood in a bottom-and-top semiautomated system using the buffy coat (BC) technique. Blood cells were counted in the resulting components. Removal efficiency of lymphocytes and granulocytes correlated with the loss of erythrocytes due to removal of the BC. Sigmoidal curves showed a good fit to experimental data. Variables of the equations differed substantially concerning removal of lymphocytes and granulocytes. Overnight storage of blood at 20-22 degrees C prior to processing resulted in changes in efficiency of leukocyte removal. Removal of lymphocytes decreased, while that of granulocytes increased due to overnight processing. Lymphocytes may be removed almost quantitatively with less than 10% (fresh blood) or 15% (overnight-stored blood) loss in erythrocyte content of the donated blood, corresponding to less than 28 ml packed red cells in the BC. Granulocytes seem to represent the residual amount of the final leukocyte content in the erythrocyte product. The present study may contribute to the production of erythrocyte products with fewer contaminating leukocytes and to the standardizing of semiautomated blood processing.