Phosphatidylethanolamine is progressively exposed in RBCs during storage

BackgroundIt is well established that as a blood unit ages, fewer of the unit's red blood cells (RBCs) remain in circulation post-transfusion. The mechanism for clearance is not well defined. Phosphatidylethanolamine (PE) is a phospholipid that is primarily found on the inner leaflet of healthy cells, and is an important ligand for phagocytosis of dead cells when exposed.ObjectivesThe objective of the present study was to measure the change in PE exposure in donor RBCs over increasing storage ages using the novel PE-specific probe, duramycin.MethodsFive adsol (AS-1) preserved RBC units were sampled weekly for 6 weeks and were labelled with duramycin. The percentage of PE exposed on red cells in each sample was determined using flow cytometry. Surface phosphatidylserine (PS) was evaluated for comparison.ResultsWe found that RBCs in AS-preserved donor units increasingly exposed PE, from less than 1% in freshly processed RBCs, to nearly 20% at 42 days of storage and correlated with increased relative vesiculation or microparticle concentration and release of cell-free haemoglobin. By comparison, only 5% of cells exposed PS at 42 days.ConclusionWe conclude that exposure of PE in the RBC outer membrane was higher than that of PS during 42 days of storage and correlated significantly with increased vesiculation and release of haemoglobin

The Use of Preliminary Scientific Evidence in Public Health: A Case Study of XMRV

Kumanan Wilson and colleagues explain how the rapid response to XMRV as a novel pathogen has highlighted some challenges pertaining to policy-making and editorial responsibilities. The impact on policy and the propagation of the initial scientific information may not cease if the evidence is disproven and retracted from the peer-reviewed literature, which creates a challenge for regulators and scientific journals. Please see later in the article for the Editors' Summar

Therapeutic impact of red blood cell transfusion on anemic outpatients: the RETRO study

BACKGROUND:Patients with cancer or other diagnoses associated with chronic anemia often receive red blood cell (RBC) transfusion as outpatients, but the effect of transfusion on functional status is not well demonstrated. STUDY DESIGN AND METHODS:To estimate the effect of transfusion on functional status and quality of life, we measured 6-minute walk test distance and fatigue- and dyspnea-related quality-of-life scores before and 1 week after RBC transfusion in 208 outpatients age ≥50 with at least one benign or malignant hematology/oncology diagnosis. To account for potential confounding effects of cancer treatment, patients were classified into two groups based on cancer treatment within 4 weeks of the study transfusion. Minimum clinically important improvements over baseline were 20 meters in walk test distance, 3 points in fatigue score, and 2 points in dyspnea score. RESULTS:The median improvement in unadjusted walk test distance was 20 meters overall and 30 meters in patients not receiving recent cancer treatment. Fatigue scores improved overall by a median of 3 points and by 4 points in patients without cancer treatment. There was no clinically important change in dyspnea scores. In multiple linear regression analysis, patients who maintained hemoglobin (Hb) levels of 8 g/dL or greater at 1 week posttransfusion, who had not received recent cancer treatment, and who did not require hospitalization during the study showed clinically important increases in mean walk test distance. CONCLUSIONS:Red blood cell transfusion is associated with a modest, but clinically important improvement in walk test distance and fatigue score outcomes in adult hematology/oncology outpatients