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 recipien t. Study Design and Methods: Daily plasma samples from platelet concen trates, both apheresis platelets and those separated from whole blood, were obtained serially during routine storage. These plasma samples w ere assayed for their ability to prime the NADPH oxidase in isolated h uman neutrophils. Quantitative and qualitative analysis of the priming agents was completed by lipid extraction, high-pressure liquid chroma tography 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 o utdate: 2.6-fold that of the buffer-treated control neutrophils (apher esis) and 3.9-fold that of the buffer-treated control neutrophils (who le blood). These agents were generated by cellular constituents, as st ored plasma did not demonstrate such priming activity. Inhibition of t his priming activity by WEB 2170, a specific platelet-activating facto r receptor antagonist, suggested that the observed priming involved th e platelet-activating factor receptor. A portion of the priming activi ty from platelet concentrates was organically extractable: 69 percent of that from apheresis platelets and 46 percent of that from whole-blo od 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 lysophosphatidylcho lines. Because 46 percent of the priming activity from whole-blood pla telets was chloroform insoluble and because it has been reported that interleukin 8 is generated during routine storage of whole-blood plate lets, 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 t he routine storage of platelet concentrates that prime the NADPH oxida se, and they may play a role in the severe complications of transfusio n 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.