Stored human platelets retain full aggregation potential in response to pairs of aggregating agents.

Human platelet concentrates stored at 22#{176}C for transfusion purposes progressively lose their in vitro sensitivity to single aggregating agents such as adenosine diphosphate (ADP). It is known that very small amounts of epinephrine. collagen. or arachidonic acid can markedly enhance the aggregation of platelets in fresh platelet-rich plasmas in response to concentrations of ADP that do not cause aggregation when used singly. Therefore. we investigated the effects of pairs of aggregating agents on eight platelet concentrates on the day of preparation and after 3 and 5 days of storage at 22#{176}C. We studied platelet aggregation and secretion with a lumi-aggregometer and thromboxaneB2 formation using a radioimmunoassay. When aggregation was tested in response to single agents. stored platelets were completely unresponsive to epinephrine. markedly insensitive to ADP, and moderately insensitive to collagen and arachidonic acid. In spite of this. there was no statistically significant loss of sensitivity to aggregating agents