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 ( BRM s) that can mediate transfusion complications in infants. The aim of this study was to examine the in vitro quality and the changes in BRM s 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 0·9% saline by centrifugation and then resuspended in SAG ‐M, while the other remained unwashed. Each RBC unit was divided to produce four units of paediatric‐sized components. Samples 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 activation, with increased cell surface expression of CD 62E (E‐selectin) and CD 106 ( VCAM ). Conclusion Although washing affected some aspects of the in vitro quality of RBC , it effectively reduced the concentration and activity of BRM s in the supernatant of RBC . Such a reduction may be clinically beneficial in selected patient groups.