Effect of platelet activation inhibitors on the loss of glycoprotein Ib during storage of platelet concentrates.
Platelet membrane glycoprotein Ib (GPIb) in stored platelet concentrates was analyzed by flow cytometry with three separate monoclonal antibodies (AN-51, 6D1, and SZ-2), by tritiated glycoprotein radiolabeling, and by ristocetin-induced agglutination. Flow cytometry showed that a population of surface GPIb-negative platelets was evident at 5 days and increased three- to fivefold by the tenth day. Tritium radiolabeling of surface GPIb showed a decrease over 10 days of 37% +/- 17%. The degree of loss of surface GPIb correlated well with other changes during storage: decreased ristocetin-induced agglutination, decreased responsiveness in the hypotonic shock test, lower plasma pH, and increased extracellular lactic dehydrogenase. Immunoblotting of total platelet GPIb with the SZ-2 antibody showed a decrease of 58% +/- 16% during the 10-day storage period. The effect of protease inhibitors or platelet activation inhibitors on the loss of GPIb during storage was studied in platelet concentrates paired with untreated controls. Only the platelet activation inhibitors prostaglandin E1 and theophylline retarded the loss of surface GPIb levels (93% +/- 5% GPIb remaining vs 65% +/- 16%). Total GPIb levels also decreased less in the presence of the activation inhibitors (45% +/- 22% lost vs 70% +/- 14% lost). These findings suggest that platelet activation, rather than plasma enzymatic activity, is responsible for the loss of platelet GPIb during storage of platelet concentrates.
Department of Clinical Pathology and Diagnostic Medicine, East Carolina University School of Medicine, Greenville, NC 27858.
A P
AP
Bode
C L
CL
Knupp
D T
DT
Miller
D000527:Alprostadil / Q000494:pharmacology; D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology; D001793:Blood Preservation; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D010447:Peptide Hydrolases / Q000378:metabolism*; D015539:Platelet Activation / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology*; D012310:Ristocetin / Q000494:pharmacology; D013806:Theophylline / Q000494:pharmacology; D013997:Time Factors
D000911:Antibodies, Monoclonal; D010980:Platelet Membrane Glycoproteins; D011480:Protease Inhibitors; D012310:Ristocetin; D013806:Theophylline; D010447:Peptide Hydrolases; D000527:Alprostadil