Analysis of the priming activity of lipids generated during routine storage of platelet concentrates

Background: Compounds generated during the routine storage of platelet concentrates may have deleterious effects on the transfusion recipient. Study Design and Methods: Daily plasma samples from platelet concentrates, both apheresis platelets and those separated from whole blood, were obtained serially during routine storage. These plasma samples were assayed for their ability to prime the NADPH oxidase in isolated human neutrophils. Quantitative and qualitative analysis of the priming agents was completed by lipid extraction, high-pressure liquid chromatography separation, and gas chromatography/mass spectroscopy. Results: Compounds were generated in both apheresis and whole-blood platelets that significantly primed the NADPH oxidase after 24 and 48 hours of storage, respectively. The priming activity was maximal by component outdate: 2.6-fold that of the buffer-treated control neutrophils (apheresis) and 3.9-fold that of the buffer-treated control neutrophils (whole blood). These agents were generated by cellular constituents, as stored plasma did not demonstrate such priming activity. Inhibition of this priming activity by WEB 2170, a specific platelet-activating factor receptor antagonist, suggested that the observed priming involved the platelet-activating factor receptor. A portion of the priming activity from platelet concentrates was organically extractable: 69 percent of that from apheresis platelets and 46 percent of that from whole-blood platelets. Further purification of the lipid's priming activity by normal-phase high-pressure liquid chromatography demonstrated a single peak of priming activity at the retention time of lysophosphatidylcholines. Because 46 percent of the priming activity from whole-blood platelets was chloroform insoluble and because it has been reported that interleukin 8 is generated during routine storage of whole-blood platelets, the effects of interleukin 8 on the NADPH oxidase were examined. Recombinant monocyte interleukin 8 rapidly primed the oxidase but was not inhibited by WEB 2170. Conclusion: Lipids were generated during the routine storage of platelet concentrates that prime the NADPH oxidase, and they may play a role in the severe complications of transfusion therapy. Other non-lipid compounds, such as interleukin 8, that are generated in whole-blood platelets may also contribute to the observed priming activity of plasma.