The effect of whole-blood storage time on the number of white cells and platelets in whole blood and in white cell-reduced red cells

BACKGROUND: Whole blood (WB) can be stored for some time before it is processed into components. After introduction of universal white cell (WBC) reduction, it was observed that longer WB storage was associated with more residual WBCs in the WBC-reduced red cells (RBCs). Also, weak propidium iodide (PI)-positive events were observed in the flow cytometric WBC counting method, presumably WBC fragments. The effect of storage time on the composition of WB and subsequently prepared WBC-reduced RBCs was studied. STUDY DESIGN AND METHODS: WB was collected in bottom-and-top collection systems with inline filters, obtained from Baxter, Fresenius, or MacoPharma. Units were stored at room temperature and separated into components in 4-hour intervals between 4 and 24 hours after collection. RBCs were WBC-reduced by inline filtration (approx. 50/group). RESULTS: Platelet (PLT) counts were lower in WB stored for 4 to 8 hours compared to 20 to 24 hours (mean +/- SD): 79 +/- 31 versus 102 +/- 30 for Baxter (p < 0.01); 91 +/- 31 versus 101 +/- 35 for Fresenius (not significant); and 73 +/- 47 versus 97 +/- 31 (all x 10(9) per unit) for MacoPharma (p < 0.01), respectively. The median residual WBC counts in WBC-reduced RBCs for WB stored for 4 to 8 and 20 to 24 hours were 0.03 versus 0.17 for Baxter (p < 0.001), 0.00 versus 0.06 for Fresenius (p < 0.001), and 0.13 versus 0.26 (all x 10(6) per unit) for MacoPharma (not significant), respectively. All WBC-reduced RBCs contained fewer than 5 x 10(6) WBCs per unit. A longer storage time of WB was associated with more weak PI-positive events, irrespective of the filter. CONCLUSION: Longer storage of WB before processing results in counting higher numbers of PLTs in WB, higher numbers of WBCs in WBC-reduced RBCs, and more weak PI-positive events.