Observations on the removal of microaggregates from stored blood by centrifugation and filtration through a standard 170 micron transfusion filter.

The effect of centrifugation (5 minutes, 6900 X g) on the amount and particle size of blood microaggregates was studied in order to assess whether centrifugation and filtration by a standard (170 micron) transfusion set filter could be used for aggregate removal instead of microfiltration. Aggregates were quantitated using a method based on nylon screens with graded pore sizes. At the beginning of storage, centrifugation increased the particle size of aggregates only slightly. In 7-day-old blood, aggregates capable of passing a 160 micron screen amounted to 308 +/- 107 (SD) mg of debris protein per liter of blood before and 55 +/- 26 (SD) mg of protein (n = 10) after centrifugation. In 14-day-old blood centrifugation increased the size of aggregates even more effectively: 311 +/- 81 (SD) before and 29 +/- 14 (SD) mg of protein following centrifugation. Microaggregates can thus be removed effectively by the centrifugation and filtration method from blood stored for more than 1 week. A standard transfusion set filter can be used instead of a micropore filter.