Generation of annexin V-positive platelets and shedding of microparticles with stimulus-dependent procoagulant activity during storage of platelets at 4 degrees C.
BACKGROUND
The ability of propyl gallate to activate platelet factor 3 has been determined through the activated partial thromboplastin time, but its effect on phosphatidylserine has not been established.


METHODS
A novel platelet activator, propyl gallate, was introduced to a study of platelets stored at 4 degrees C. The effects of storage on platelet coagulation activity, on phosphatidylserine, and on the shedding of activated and activable membrane particles (microparticles) were examined by activated plasma clotting time, and the effect on annexin V binding was examined by gated flow cytometry. The ratios of annexin V binding and microparticle shedding in stored platelet samples were compared with those in fresh platelets stimulated with propyl gallate.


RESULTS
Microparticle shedding by stored platelets compensated for the diminished procoagulant potential of intact platelets (shown as the total propyl gallate-dependent platelet factor 3 activity), which did not change during prolonged (20-day) storage, but levels of phosphatidylserine confined to microparticles increased dramatically as platelet counts fell. Both annexin V binding and microparticle shedding increased spontaneously with storage and artificially with propyl gallate stimulation. However, at the same level of annexin V binding, stored platelets shed more microparticles than did fresh platelets stimulated with propyl gallate.


CONCLUSIONS
Propyl gallate induces platelet procoagulant activity and annexin V binding. Stored platelets differ from fresh platelets in a lower reactivity to propyl gallate activation and a higher rate of microparticle shedding.
Xiao
H Y
HY
Methodist Research Institute, Indianapolis, IN 46202, USA. hxiao@clarian.com
Matsubayashi
H
H
Bonderman
D P
DP
Bonderman
P W
PW
Reid
T
T
Miraglia
C C
CC
Gao
D Y
DY
D000328:Adult; D017304:Annexin A5 / Q000097:blood* / Q000378:metabolism; D001780:Blood Coagulation Tests; D001792:Blood Platelets / Q000737:chemistry*; D001793:Blood Preservation; D015925:Cryopreservation; D005434:Flow Cytometry; D006801:Humans; D008563:Membrane Lipids; D010977:Platelet Factor 3 / Q000378:metabolism; D011435:Propyl Gallate / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D017304:Annexin A5; D008563:Membrane Lipids; D010977:Platelet Factor 3; D011435:Propyl Gallate