Flow Cytometric Measurement of CD41/CD61 and CD42b Platelet Receptors and Clotting Assay of Platelet Factor 3 During Long Term-Storage of Platelet Concentrates

The purpose of the present in vitro study was to evaluate the effect of long term storage of conventional platelet concentrates (PCs) on major platelet receptors CD42b and CD41/CD61 by flow cytometry method and also measuring the overall platelet procoagulant activity status using platelet factor 3 (PF3) assay. Six random units of conventional platelet concentrate were prepared and after collection and resting period, were placed in a standard platelet incubator under continuous agitation at 22-24°C for eleven days. Samples of each platelet concentrate unit were taken on days 1, 5 and 11 after their preparation. Two types of samples; one pooled sample for flow cytometry analysis and also individual samples for PF3 assay were prepared and tested. Flow cytometric analysis of CD41, CD61 and CD42b found 99.8%, 94.8% and 28% activity on the first day which decreased to 68.3%, 75.1% and 3.4% respectively at the end of the storage period (11 days). The overall platelet procoagulant activity status measured by PF3 assay was 95.0% and 41.7% at the beginning and the end of the storage period respectively. Our results indicated that storage lesion occurs during long-term storage of platelets with a nearly constant slope. In spite of lower expression of CD42b, higher expression levels of CD41/CD61 and platelet procoagulant activity measured by PF3 method were observed at the end of the storage period which confirms that platelet procoagulant properties are moderately preserved even after an eleven days period.