Physical characteristics of microaggregates in stored blood.

Abstract

The volume of microaggregates 13 to 80 μ in size which developed in blood components stored under varying conditions was measured with a particle size analyzer. The microaggregates were found to develop progressively during storage of ACD whole blood at 4 to 6 C. Coincident with this there was a drop in the platelet count during the first week of storage and a progressive reduction in the absolute granulocyte count. Microaggregate development after storage of various components of ACD blood was proportional to the concentration of platelets and leukocytes prior to storage. The microaggregates settled into the buffy coat after centrifugation and became larger. In vitro studies indicated that they were resistant to dissociation in vitro in comparison to platelet aggregates induced in fresh blood by adenosine diphosphate. Microaggregate formation was greater in CPD than in ACD anticoagulated blood stored at 4 to 6 C for 24 hours, but was not different after seven days of storage. A greater volume of microaggregates was formed in aliquots of ACD blood stored at 4 to 6 C than at room temperature, while no differences were noted after storage of blood in plastic bags or glass vacuum bottles.