Reduction of biological response modifiers in the supernatant of washed paediatric red blood cells

Background: Washing of red blood cells (RBC) can reduce unwanted biological response modifiers (BRMs) that can mediate transfusion complications in infants. The aim of this study was to examine the in vitro quality and the changes in BRMs following washing in paediatric RBC units. Materials and Methods: A pool and split design was used to prepare RBC (either 1 or 4 days old; n = 26 pairs). One unit was washed with 09% saline by centrifuga- tion and then resuspended in SAG-M, while the other remained unwashed. Each RBC unit was divided to produce four units of paediatric-sized components. Sam- ples were taken after 3 h and subsequently on days 1, 2, 7 and 14 post-wash. Results: Washing of RBC resulted in some red cell loss, with a minor increase in haemolysis. Washing effectively reduced supernatant potassium and IgA, as well as cytokines and complement proteins. RBC microparticles were significantly reduced in RBC washed at 1, but not 4 days post-collection. Incubation with supernatant from unwashed but not washed RBC led to endothelial cell activa- tion, with increased cell surface expression of CD62E (E-selectin) and CD106 (VCAM). Conclusion: Although washing affected some aspects of the in vitro quality of RBC, it effectively reduced the concentration and activity of BRMs in the super- natant of RBC. Such a reduction may be clinically beneficial in selected patient groups.Y. S. Loh, S. Tan, M. J. Stark, D.C. Mark