A two-event in vitro model of acute chest syndrome: the role of secretory phospholipase A2 and neutrophils.

BACKGROUND: Acute chest syndrome (ACS) in sickle cell disease is associated with elevation of secretory phospholipase A(2) (sPLA(2) ). We hypothesize that sPLA(2) cleaves membrane lipids from sickled red blood cells (RBCs) causing PMN-mediated endothelial cell injury (ECI) as the second event in a two-event model. METHODS: Whole blood was collected from children when in steady state or daily during admissions for vaso-occlusive pain (VOC) or ACS. The plasma and RBCs were separated, sPLA(2) levels were measured, and the RBCs were incubated with sPLA(2) . Plasma and lipids, extracted from the plasma or the supernatant of sPLA(2) -treated RBCs, were assayed for PMN priming activity and used as the second event in a model of PMN-mediated ECI. Phosphatidylserine (PS) surface expression on RBCs was quantified by flow cytometry. RESULTS: Increased sPLA(2) -IIa levels were associated with ACS. SPLA(2) -liberated lipids from VOC and the plasma, plasma lipids and sPLA(2) -liberated lipids from ACS primed PMNs and caused PMN-mediated ECI (P < 0.01). RBCs from VOC had increased in PS surface expression versus steady state. CONCLUSIONS: ACS plasma and lipids and sPLA(2) -released lipids from RBCs during VOC or ACS induce PMN-mediated ECI. VOC elicited increases in PS surface expression providing a membrane substrate for sPLA(2) lysis of sickle RBCs.

Mirasol Pathogen Reduction Technology treatment does not affect acute lung injury in a two-event in vivo model caused by stored blood components.

INTRODUCTION: Mirasol Pathogen Reduction Technology (PRT) treatment uses riboflavin and UV light to inactivate pathogens in blood components. Neutrophil [polymorphonuclear cells (PMN)] priming activity accumulates during routine storage of cellular blood components, and this activity has been implicated in transfusion-related acute lung injury (TRALI). We hypothesize that PRT-treatment of blood components affects the priming activity generated during storage of packed RBCs (PRBCs) or platelet concentrates (PCs), which can elicit ALI in vivo. METHODS: Plasma, PRBCs and PCs were isolated from healthy donor's whole blood or by apheresis. Half of a collected unit was treated with PRT treatment and the remainder was left as an unmodified control. Supernatant was collected during storage of PCs and PRBCs and assayed for PMN priming activity and used as the second event in a two-event in vivo model of TRALI. RESULTS: PRT treatment did not induce priming activity in plasma or affect the priming activity generated during storage of PCs or PRBCs as compared with the unmodified controls. The supernatants from stored, but not fresh, PCs and PRBCs did cause ALI as the second event in a two-event animal model of TRALI, which was unaffected by PRT treatment. We conclude that the PRT treatment does not induce priming activity in plasma nor does it affect the priming activity generated during storage of PCs or PRBCs or their ability to cause ALI as the second event in a two-event in vivo model of TRALI. Moreover, the amount of priming activity in TRIMA-isolated PCs was significantly less than SPECTRA-isolated PCs.

Transfusion-related acute lung injury (TRALI): current concepts and misconceptions.

Transfusion-related acute lung injury (TRALI) is the most common cause of serious morbidity and mortality due to hemotherapy. Although the pathogenesis has been related to the infusion of donor antibodies into the recipient, antibody negative TRALI has been reported. Changes in transfusion practices, especially the use of male-only plasma, have decreased the number of antibody-mediated cases and deaths; however, TRALI still occurs. The neutrophil appears to be the effector cell in TRALI and the pathophysiology is centered on neutrophil-mediated endothelial cell cytotoxicity resulting in capillary leak and ALI. This review will detail the pathophysiology of TRALI including recent pre-clinical data, provide insight into newer areas of research, and critically assess current practices to decrease it prevalence and to make transfusion safer.