The reprdoucible platelet production cycle following infusion of fresh frozen plasma (FFP) in a girl with chronic thrombocytopenia [Blood 16: 943, 1960] provided a unique opportunity to study the functional capacity of young and old platelets. Study cycles were initiated by infusing FFP when the patient's platelet count was less than 20,000/mm3. ‘Young’ platelet studies were done 4 days after FFP when the patient's platelet count was less than 20,000/mm3); ‘old’ platelet studies were done 21 days after FFP (average platelet count, 200,000/mm3). All studies were repeated during several such cycles. In association with a young platelet population, were normal Ivy bleeding times, normal or increased platelet adhesiveness, normal aggregation to ADP and collagen, and normal platelet factor 3 availability (PF-3a). By contrast, when the patient's circulating platelets were old, she was found to have long bleeding times, abnormally low adhesiveness in vivo and in vitro, and decreased PF-3a. Aggregation to ADP and collgen was slightly decreased but remained within normal limits. No abnormalities were seen by electron microscopy on platelet samples obtained throughout the cycle. (Performed by Dr. JAMES WHITE, Univ. of Minn.) It is of interest that on several occasions the patient experienced mild bleeding manifestations at the end of a cycle but while her platelet count was still normal. These episodes correlated with the findings of long bleeding time and decreased adhesiveness.
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Johnson, C., Abildgaard, C. & Schulman, I. Functional Studies of Toung Versus Old Platelets in a Patient with Chronic Thrombocytopenia. Pediatr Res 4, 464–465 (1970). https://doi.org/10.1203/00006450-197009000-00122