Platelet-white blood cell (WBC) interaction, WBC apoptosis, and procoagulant activity in stored red blood cells.
BACKGROUND
Nonleukoreduced units of red blood cells (RBCs) contain activated platelets (PLTs) that interact with white blood cells (WBCs) and may promote inflammation and thrombosis in the recipient. The aim of this study was to characterize PLT-WBC interactions (PLT-WBC aggregates [PLAs]), WBC apoptosis, WBC death, and the development of procoagulant activity in RBCs during storage.


METHODS
RBCs were prepared from volunteer donor blood and stored. Samples were analyzed with flow cytometry between Days 1 and 15 to measure PLT-monocyte aggregate (PMA) and PLT-neutrophil aggregate (PNA) formation, WBC apoptosis (annexin V binding), and cell death (binding of 7-aminoactinomycin D). Procoagulant activity in the supernatant of four RBC preparations was assessed between Days 1 and 39 using a clotting assay with and without the addition of an inhibitory anti-tissue factor (TF) antibody, αTF-5.


RESULTS
PLA formation was extensive and maximal on Day 3 of storage (PNA, 23 ± 13%; PMA, 93 ± 4%; n = 6). Apoptosis was progressive throughout storage, with 95 ± 4% of neutrophils and 73 ± 19% of monocytes binding annexin V on Day 15. Cell death became measurable after apoptosis. Procoagulant activity was observed in all RBCs but with varying temporal patterns. It was partially TF dependent and removed with high-speed centrifugation, suggestive of an association with microparticles.


CONCLUSIONS
The activation of PLTs during the storage of RBCs induces PLA formation that precedes WBC apoptosis and death. Procoagulant activity, likely associated with microparticles derived from apoptotic WBCs, may contribute to adverse effects of stored, nonleukoreduced RBCs.
Department of Medicine, University of Vermont, Burlington, Vermont, USA. friederike.keating@vtmednet.org
Friederike K
FK
Keating
Saulius
S
Butenas
Mark K
MK
Fung
David J
DJ
Schneider
D017209:Apoptosis / Q000502:physiology; D001779:Blood Coagulation Factors / Q000378:metabolism*; D001792:Blood Platelets / Q000166:cytology* / Q000502:physiology; D001793:Blood Preservation / Q000009:adverse effects*; D002450:Cell Communication / Q000502:physiology; D055252:Cell-Derived Microparticles / Q000502:physiology; D004912:Erythrocytes / Q000166:cytology* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D009000:Monocytes / Q000166:cytology*; D009504:Neutrophils / Q000166:cytology; D015539:Platelet Activation / Q000502:physiology; D013925:Thromboplastin / Q000378:metabolism
D001779:Blood Coagulation Factors; C045071:leukocyte procoagulant activity; D013925:Thromboplastin