Prestorage leucocyte reduction of red cell components prevents release of bactericidal permeability increasing protein and defensins.

BACKGROUND AND OBJECTIVES In this study we examined whether prestorage leucocyte reduction prevents the accumulation of bioreactive substances in red cell units. MATERIALS AND METHODS Measurements were performed in the supernatants of buffy-coat-depleted (standard red cells) and leucocyte-reduced (filtered red cells) red cell units. The effect of storage was evaluated by taking repetitive samples up to 35 days after donation. We determined the concentrations of polymorphonuclear neutrophil (PMN)-derived bactericidal permeability increasing protein (BPI), defensins and annexin A5. In addition, leucocyte counts (using nageotte chamber) were performed on days 0 and 35. RESULTS During storage, the concentrations of BPI, defensins and annexin A5 in standard red cells gradually increased. However, in the filtered red cells BPI and defensins were found in only a few samples, whereas the annexin A5 concentration in these units did not change during storage. Haemolysis data in both types of red cell components were similar at all time-points, except prestorage. Significant correlations were found between the release of BPI, defensins and annexin A5 into red cell units and the loss of leucocytes during storage. CONCLUSIONS PMNs lose their membrane integrity during cold storage and release their contents into red cell components. Prestorage leucocyte reduction of red cell components prevents the accumulation of BPI, defensins and annexin A5.