Altered in vitro functions of platelets prepared by the Haemonetics blood processor

The function and ultrastructure of platelets collected by the Haemonetics blood processor were investigated. Aggregability, release ability, and morphology of these platelets were compared with platelets of the same donors before plateletpheresis was instiuted. Data of a group of 15 normal donors were pooled and analyzed. Our results showed that Haemonetics-isolated platelets had the following altered in vitro functions. Adenosine diphosphate-induced aggregation was markedly reduce, and epinephrine-induced aggregation was often absent. Collagen-induced aggregation was characterized by prolongation of the aggregation time and, sometimes, also by reduction of aggregation. Increase of adenosine diphosphate or collagen concentration resulted in improvement of aggregation of Haemonetics-collected platelets; increase of epinephrine concentration had no effect. Exogenous CaCL2, pre-Haemonetics platelet-rich or platelet-poor plasma failed to correct the abnormal aggregation of post-Haemonetics platelets. Release of labeled serotonin induced by spinephrine and collagen was reduced. However, the ultrastructure of post-Haemonetics platelets was normal.