The expression of p-selectin during collection, processing, and storage of platelet concentrates: relationship to loss of in vivo viability.
BACKGROUND
Recent studies suggested that platelet activation with surface expression of p-selectin on stored platelets may be related to a loss of viability. At present, there has been no thorough investigation of the extent or significance of p-selectin expression during the collection, processing, and storage of platelet concentrates (PCs) under various conditions.


METHODS
Platelet surface expression of p-selectin (CD62) was determined on fixed platelet samples using fluorescein-conjugated monoclonal antibodies. Platelet viability was assessed by autologous transfusion of platelets stored for 5 days and labeled with either 51Cr or 111in.


RESULTS
Little (2-10%) platelet expression of p-selectin was found in whole blood and platelet-rich-plasma preparations, whereas PCs showed a substantial increase in p-selectin expression to levels of 20 to 30 percent. Both fresh PCs and those stored for 5 days, obtained with one cell separator (MCS, Haemonetics) showed substantially lower levels of p-selectin expression than PCs from two other cell separators (Spectra, COBE, and CS-3000 with TNX-6, Baxter Healthcare). Exposure of platelets to EDTA, cold, or a pH below 6.2, conditions that are known to result in the loss of viability upon transfusion, produced substantial and irreversible p-selectin expression. PCs with a pH of 6.2 to 6.8 (conditions in which no loss of viability has been demonstrated) also showed pronounced p-selectin expression, which returned to control values after incubation at 37 degrees C in plasma at pH 7.0 to 7.2. With storage under current conditions the in vivo studies (n = 61) demonstrated a rather poor correlation between p-selectin expression and the percentage of recovery (r = -0.25) but a somewhat better correlation with survival (r = -0.42). Better correlations were observed with the extent of shape change, lactate, and hypotonic shock response.


CONCLUSIONS
These studies show that p-selectin expression on the platelet surface is a predictor of platelet viability, although the extent of shape change and the hypotonic shock response may be more sensitive.
Holme
S
S
American Red Cross, Norfolk, Virginia, USA.
Sweeney
J D
JD
Sawyer
S
S
Elfath
M D
MD
D001792:Blood Platelets / Q000166:cytology*; D001793:Blood Preservation; D001800:Blood Specimen Collection; D002470:Cell Survival / Q000187:drug effects; D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D019007:P-Selectin / Q000096:biosynthesis*; D013048:Specimen Handling; D001620:beta-Thromboglobulin / Q000032:analysis
D019007:P-Selectin; D001620:beta-Thromboglobulin; D004492:Edetic Acid