Survival of transfused red blood cells from a donor with alpha-thalassemia trait in a recipient with sickle cell disease

BACKGROUND

Post-transfusion survival of donor red blood cells (RBCs) is important for effective chronic transfusion therapy in conditions including sickle cell disease (SCD). Biotin labeling RBCs allows direct in vivo measurement of multiple donor RBC units simultaneously post-transfusion.

STUDY DESIGN AND METHODS

In an observational trial of patients with SCD receiving monthly chronic transfusion therapy, aliquots of RBCs from one transfusion episode were biotin-labeled and infused along with the unlabeled RBC units. Serial blood samples were obtained to measure RBC survival. Donor units were tested for RBC indices, hemoglobin fractionation, and glucose-6-phosphate dehydrogenase (G6PD) enzyme activity. For microcytic donor RBCs (MCV < 70 fL), HBA1 and HBA2 genetic testing was performed on whole blood.

RESULTS

We present one recipient, a pediatric patient with SCD and splenectomy who received two RBC units with aliquots from each unit labeled at distinct biotin densities (2 and 18 μg/mL biotin). One donor unit was identified to have microcytosis (MCV 68.5 fL after biotinylation); whole blood sample obtained at a subsequent donation showed 2-gene deletion alpha-thalassemia trait (ɑ-3.7kb/ɑ-3.7kb) and normal serum ferritin. G6PD activity was >60% of normal mean for both. The RBCs with alpha-thalassemia RBC had accelerated clearance and increased surface phosphatidylserine post-transfusion, as compared with the normocytic RBC (half life 65 vs. 86 days, respectively).

DISCUSSION

Post-transfusion RBC survival may be lower for units from donors with alpha-thalassemia trait, although the impact of thalassemia trait donors on transfusion efficacy requires further study.

Accuracy of automated analyzers for the estimation of CSF cell counts: A systematic review and meta-analysis

This systematic review evaluates the evidence for accuracy of automated analyzers that estimate cerebrospinal fluid (CSF) white blood cell counts (WBC) compared to manual microscopy. Inclusion criteria of original research articles included human subjects, English language, and manual microscopy comparator. PUBMED, EMBASE and Cochrane Review databases were searched through 2019 and QUADAS-2 Tool was used for assessment of bias. Data were pooled and analyzed by comparison method, using random effects estimation. Among 652 titles, 554 abstracts screened, 104 full-text review, 111 comparisons from 41 studies were included. Pooled estimates of sensitivity and specificity (n = 7) were 95% (95%-CI 93%-97%) and 84% (95%-CI: 64%-96%), respectively. Pooled R2 estimates (n = 29) were 0.95 (95%-CI: 0.95-0.96); Pooled spearman rho correlation (n = 27) estimates were 0.95 (95% CI 0.95-0.96). Among those comparisons using Bland-Altman analysis (n = 11) pooled mean difference was estimated at 0.98 (95% CI-0.54-2.5). Among comparisons using Passing-Bablok regressions (n = 14) the pooled slope was estimated to be 1.05 (95% CI 1.03-1.07). Q tests of homogeneity were all significant with the exception of the Bland-Altman comparisons (I2 10%, p value 0.35). There is good overall accuracy for CSF WBC by automated hematologic analyzers. These findings are limited by the small sample sizes and inconsistent validation methodology in the reviewed studies.

Admission viscoelastic hemostatic assay parameters predict poor long-term intracerebral hemorrhage outcomes

Background

Viscoelastic hemostatic assays (VHA) provide more comprehensive assessments of coagulation compared to conventional coagulation assays. While VHAs have enabled guided hemorrhage control therapies, improving clinical outcomes in life-threatening hemorrhage, the role of VHAs in intracerebral hemorrhage (ICH) is unclear. If VHAs can identify coagulation abnormalities relevant for ICH outcomes, this would support the need to investigate the role of VHAs in ICH treatment paradigms. Thus, we investigated whether VHA assessments of coagulation relate to long-term ICH outcomes.

Methods

Spontaneous ICH patients enrolled into a single-center cohort study receiving admission Rotational Thromboelastometry (ROTEM) VHA testing between 2013 and 2020 were assessed. Patients with prior anticoagulant use or coagulopathy on conventional coagulation assays were excluded. Primary ROTEM exposure variables were coagulation kinetics and clot strength assessments. Poor long-term outcome was defined as modified Rankin Scale ≥ 4 at 6 months. Logistic regression analyses assessed associations of ROTEM parameters with clinical outcomes after adjusting for ICH severity and hemoglobin concentration.

Results

Of 44 patients analyzed, mean age was 64, 57% were female, and the median ICH volume was 23 mL. Poor 6-month outcome was seen in 64%. In our multivariable regression models, slower, prolonged coagulation kinetics (adjusted OR for every second increase in clot formation time: 1.04, 95% CI: 1.00-1.09, p = 0.04) and weaker clot strength (adjusted OR for every millimeter increase of maximum clot firmness: 0.84, 95% CI: 0.71-0.99, p = 0.03) were separately associated with poor long-term outcomes.

Conclusions

Slower, prolonged coagulation kinetics and weaker clot strength on admission VHA ROTEM testing, not attributable to anticoagulant use, were associated with poor long-term outcomes after ICH. Further work is needed to clarify the generalizability and the underlying mechanisms of these VHA findings to assess whether VHA guided treatments should be incorporated into ICH care.

Low-Dose Dietary Fish Oil Improves RBC Deformability without Improving Post-Transfusion Recovery in Mice

Long-chain polyunsaturated fatty acids (LC-PUFAs) are important modulators of red blood cell (RBC) rheology. Dietary LC-PUFAs are readily incorporated into the RBC membrane, improving RBC deformability, fluidity, and hydration. Female C57BL/6J mice consumed diets containing increasing amounts of fish oil (FO) ad libitum for 8 weeks. RBC deformability, filterability, and post-transfusion recovery (PTR) were evaluated before and after cold storage. Lipidomics and lipid peroxidation markers were evaluated in fresh and stored RBCs. High-dose dietary FO (50%, 100%) was associated with a reduction in RBC quality (i.e., in vivo lifespan, deformability, lipid peroxidation) along with a reduced 24 h PTR after cold storage. Low-dose dietary FO (6.25-12.5%) improved the filterability of fresh RBCs and reduced the lipid peroxidation of cold-stored RBCs. Although low doses of FO improved RBC deformability and reduced oxidative stress, no improvement was observed for the PTR of stored RBCs. The improvement in RBC deformability observed with low-dose FO supplementation could potentially benefit endurance athletes and patients with conditions resulting from reduced perfusion, such as peripheral vascular disease.

Hemoglobin Concentration Impacts Viscoelastic Hemostatic Assays in ICU Admitted Patients

OBJECTIVES

Low hemoglobin concentration impairs clinical hemostasis across several diseases. It is unclear whether hemoglobin impacts laboratory functional coagulation assessments. We evaluated the relationship of hemoglobin concentration on viscoelastic hemostatic assays in intracerebral hemorrhage (ICH) and perioperative patients admitted to an ICU.

DESIGN

Observational cohort study and separate in vitro laboratory study.

SETTING

Multicenter tertiary referral ICUs.

PATIENTS

Two acute ICH cohorts receiving distinct testing modalities: rotational thromboelastometry (ROTEM) and thromboelastography (TEG), and a third surgical ICU cohort receiving ROTEM were evaluated to assess the generalizability of findings across disease processes and testing platforms. A separate in vitro ROTEM laboratory study was performed utilizing ICH patient blood samples.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Relationships between baseline hemoglobin and ROTEM/TEG results were separately assessed across patient cohorts using Spearman correlations and linear regression models. A separate in vitro study assessed ROTEM tracing changes after serial hemoglobin modifications from ICH patient blood samples. In both our ROTEM (n = 34) and TEG (n = 239) ICH cohorts, hemoglobin concentrations directly correlated with coagulation kinetics (ROTEM r: 0.46; p = 0.01; TEG r: 0.49; p < 0.0001) and inversely correlated with clot strength (ROTEM r: -0.52, p = 0.002; TEG r: -0.40, p < 0.0001). Similar relationships were identified in perioperative ICU admitted patients (n = 121). We continued to identify these relationships in linear regression models. When manipulating ICH patient blood samples to achieve lower hemoglobin concentrations in vitro, we similarly identified that lower hemoglobin concentrations resulted in progressively faster coagulation kinetics and greater clot strength on ROTEM tracings.

CONCLUSIONS

Lower hemoglobin concentrations have a consistent, measurable impact on ROTEM/TEG testing in ICU admitted patients, which appear to be artifactual. It is possible that patients with low hemoglobin may appear to have normal viscoelastic parameters when, in fact, they have a mild hypocoagulable state. Further work is required to determine if these tests should be corrected for a patient's hemoglobin concentration.

A randomized trial of blood donor iron repletion on red cell quality for transfusion and donor cognition and well-being

Although altruistic regular blood donors are vital for the blood supply, many become iron deficient from donation-induced iron loss. The effects of blood donation-induced iron deficiency on red cell transfusion quality or donor cognition are unknown. In this double-blind, randomized trial, adult iron-deficient blood donors (n = 79; ferritin < 15 μg/L and zinc protoporphyrin >60 μMol/mol heme) who met donation qualifications were enrolled. A first standard blood donation was followed by the gold-standard measure for red cell storage quality: a 51-chromium posttransfusion red cell recovery study. Donors were then randomized to intravenous iron repletion (1 g low-molecular-weight iron dextran) or placebo. A second donation ∼5 months later was followed by another recovery study. Primary outcome was the within-subject change in posttransfusion recovery. The primary outcome measure of an ancillary study reported here was the National Institutes of Health Toolbox-derived uncorrected standard Cognition Fluid Composite Score. Overall, 983 donors were screened; 110 were iron-deficient, and of these, 39 were randomized to iron repletion and 40 to placebo. Red cell storage quality was unchanged by iron repletion: mean change in posttransfusion recovery was 1.6% (95% confidence interval -0.5 to 3.8) and -0.4% (-2.0 to 1.2) with and without iron, respectively. Iron repletion did not affect any cognition or well-being measures. These data provide evidence that current criteria for blood donation preserve red cell transfusion quality for the recipient and protect adult donors from measurable effects of blood donation-induced iron deficiency on cognition. This trial was registered at www.clinicaltrials.gov as NCT02889133 and NCT02990559.

Genome-wide metabolite quantitative trait loci analysis (mQTL) in red blood cells from volunteer blood donors

The red blood cell (RBC)-Omics study, part of the larger NHLBI-funded Recipient Epidemiology and Donor Evaluation Study (REDS-III), aims to understand the genetic contribution to blood donor RBC characteristics. Previous work identified donor demographic, behavioral, genetic, and metabolic underpinnings to blood donation, storage, and (to a lesser extent) transfusion outcomes, but none have yet linked the genetic and metabolic bodies of work. We performed a genome-wide association (GWA) analysis using RBC-Omics study participants with generated untargeted metabolomics data to identify metabolite quantitative trait loci in RBCs. We performed GWA analyses of 382 metabolites in 243 individuals imputed using the 1000 Genomes Project phase 3 all-ancestry reference panel. Analyses were conducted using ProbABEL and adjusted for sex, age, donation center, number of whole blood donations in the past 2 years, and first 10 principal components of ancestry. Our results identified 423 independent genetic loci associated with 132 metabolites (p < 5×10^-8). Potentially novel locus-metabolite associations were identified for the region encoding heme transporter FLVCR1 and choline and for lysophosphatidylcholine acetyltransferase LPCAT3 and lysophosphatidylserine 16.0, 18.0, 18.1, and 18.2; these associations are supported by published rare disease and mouse studies. We also confirmed previous metabolite GWA results for associations, including N(6)-methyl-L-lysine and protein PYROXD2 and various carnitines and transporter SLC22A16. Association between pyruvate levels and G6PD polymorphisms was validated in an independent cohort and novel murine models of G6PD deficiency (African and Mediterranean variants). We demonstrate that it is possible to perform metabolomics-scale GWA analyses with a modest, trans-ancestry sample size.

Retention of functional mitochondria in mature red blood cells from patients with sickle cell disease

Sickle cell disease (SCD) is an inherited blood disorder characterized by sickled red blood cells (RBCs), which are more sensitive to haemolysis and can contribute to disease pathophysiology. Although treatment of SCD can include RBC transfusion, patients with SCD have high rates of alloimmunization. We hypothesized that RBCs from patients with SCD have functionally active mitochondria and can elicit a type 1 interferon response. We evaluated blood samples from more than 100 patients with SCD and found elevated frequencies of mitochondria in reticulocytes and mature RBCs, as compared to healthy blood donors. The presence of mitochondria in mature RBCs was confirmed by flow cytometry, electron microscopy, and proteomic analysis. The mitochondria in mature RBCs were metabolically competent, as determined by enzymatic activities and elevated levels of mitochondria-derived metabolites. Metabolically-active mitochondria in RBCs may increase oxidative stress, which could facilitate and/or exacerbate SCD complications. Coculture of mitochondria-positive RBCs with neutrophils induced production of type 1 interferons, which are known to increase RBC alloimmunization rates. These data demonstrate that mitochondria retained in mature RBCs are functional and can elicit immune responses, suggesting that inappropriate retention of mitochondria in RBCs may play an underappreciated role in SCD complications and be an RBC alloimmunization risk factor.

Impact of preemptive rapid testing for glucose-6-phosphate dehydrogenase deficiency prior to rasburicase administration at a tertiary care center: a retrospective study

AIM

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common enzymopathy in humans, can cause acute hemolysis resulting from exposure to certain medications, chemicals, infections and fava beans. Rasburicase, used to manage elevated uric acid levels in the oncologic emergency of tumor lysis syndrome, is one such drug. The Food & Drug Administration (FDA) recommends testing of G6PD status prior to rasburicase administration for patients at higher risk for G6PD deficiency.

METHODS

We performed a retrospective chart review of all oncology patients for whom a semi-quantitative biochemical test for detecting G6PD deficiency was performed prior to rasburicase administration over a 2.5 year period, in a large academic metropolitan hospital.

RESULTS

We identified 16 out of 260 tested individuals as G6PD-deficient (6.1%), including six females. On average, test results were electronically available to health-care providers within 4 hours of sample collection, with most results available within 2-3 hours. Four G6PD-deficient patients developed elevated uric acid levels. Two of the G6PD-deficient patients were treated with rasburicase, and subsequently developed hemolysis, which was appropriately managed.

CONCLUSION

In summary, by providing information about G6PD status with a rapid turnaround time, we have taken a significant step towards personalized medicine in our institution. In spite of the test implementation, two out of four G6PD deficient patients, who were no longer candidates for rasburicase use, still received the drug, highlighting the need for improved provider education.

Glucose-6-phosphate dehydrogenase deficiency is more prevalent in Duffy-null red blood cell transfusion in sickle cell disease

BACKGROUND

Resistance to malaria infection may be conferred by erythrocyte genetic variations including glucose-6-phosphate dehydrogenase (G6PD) deficiency and lack of Duffy antigens. In red blood cell (RBC) transfusion, G6PD deficiency may shorten transfusion survival. Because Duffy-null units are commonly transfused in sickle cell disease (SCD) due to antigen matching protocols, we examined whether Duffy-null donor RBC units have a higher prevalence of G6PD deficiency.

MATERIALS AND METHODS

Pediatric patients with SCD on chronic transfusion therapy were followed prospectively for multiple transfusions. RBC unit segments were collected to measure G6PD activity and RBC genotyping. The decline in donor hemoglobin (ΔHbA) following transfusion was assessed from immediate posttransfusion estimates and HbA measurements approximately 1 month later.

RESULTS

Of 564 evaluable RBC units, 59 (10.5%) were G6PD deficient (23 severe, 36 moderate deficiency); 202 (37.6%) units were Duffy-null. G6PD deficiency occurred in 40 (19.8%) Duffy-null units versus 15 (4.5%) Duffy-positive units (p < .0001). In univariate analysis, the fraction of Duffy-null RBC units per transfusion was associated with greater decline in HbA (p = .038); however, in multivariate analysis, severe G6PD deficiency (p = .0238) but not Duffy-null RBC (p = .0139) were associated with ΔHbA.

CONCLUSION

Selection of Duffy-null RBC units may result in shorter in vivo survival of transfused RBCs due to a higher likelihood of transfusing units from G6PD deficient donors.

The Impact of Age and BMI on the VWF/ADAMTS13 Axis and Simultaneous Thrombin and Plasmin Generation in Hospitalized COVID-19 Patients

Aging and obesity independently contribute toward an endothelial dysfunction that results in an imbalanced VWF to ADAMTS13 ratio. In addition, plasma thrombin and plasmin generation are elevated and reduced, respectively, with increasing age and also with increasing body mass index (BMI). The severity risk of Corona Virus Disease 2019 (COVID-19) increases in adults older than 65 and in individuals with certain pre-existing health conditions, including obesity (>30 kg/m²). The present cross-sectional study focused on an analysis of the VWF/ADAMTS13 axis, including measurements of von Willebrand factor (VWF) antigen (VWF:AG), VWF collagen binding activity (VWF:CBA), Factor VIII antigen, ADAMTS13 antigen, and ADAMTS13 activity, in addition to thrombin and plasmin generation potential, in a demographically diverse population of COVID-19 negative (−) (n = 288) and COVID-19 positive (+) (n = 543) patient plasmas collected at the time of hospital presentation. Data were analyzed as a whole, and then after dividing patients by age (<65 and ≥65) and independently by BMI [<18.5, 18.5–24.9, 25–29.9, >30 (kg/m²)]. These analyses suggest that VWF parameters (i.e., the VWF/ADAMTS13 activity ratio) and thrombin and plasmin generation differed in COVID-19 (+), as compared to COVID-19 (−) patient plasma. Further, age (≥65) more than BMI contributed to aberrant plasma indicators of endothelial coagulopathy. Based on these findings, evaluating both the VWF/ADAMTS13 axis, along with thrombin and plasmin generation, could provide insight into the extent of endothelial dysfunction as well as the plasmatic imbalance in coagulation and fibrinolysis potential, particularly for at-risk patient populations.

Deuterated Linoleic Acid Attenuates the RBC Storage Lesion in a Mouse Model of Poor RBC Storage

Background: Long-chain polyunsaturated fatty acids (PUFAs) are important modulators of red blood cell (RBC) rheology. Dietary PUFAs are readily incorporated into the RBC membrane, improving RBC deformability, fluidity, and hydration. However, enriching the lipid membrane with PUFAs increases the potential for peroxidation in oxidative environments (e.g., refrigerated storage), resulting in membrane damage. Substitution of bis-allylic hydrogens with deuterium ions in PUFAs decreases hydrogen abstraction, thereby inhibiting peroxidation. If lipid peroxidation is a causal factor in the RBC storage lesion, incorporation of deuterated linoleic acid (DLA) into the RBC membrane should decrease lipid peroxidation, thereby improving RBC lifespan, deformability, filterability, and post-transfusion recovery (PTR) after cold storage. Study Design and Methods: Mice associated with good (C57BL/6J) and poor (FVB) RBC storage quality received diets containing 11,11-D2-LA Ethyl Ester (1.0 g/100 g diet; deuterated linoleic acid) or non-deuterated LA Ethyl Ester (control) for 8 weeks. Deformability, filterability, lipidomics, and lipid peroxidation markers were evaluated in fresh and stored RBCs. Results: DLA was incorporated into RBC membranes in both mouse strains. DLA diet decreased lipid peroxidation (malondialdehyde) by 25.4 and 31% percent in C57 mice and 12.9 and 79.9% in FVB mice before and after cold storage, respectively. In FVB, but not C57 mice, deformability filterability, and post-transfusion recovery were significantly improved. Discussion: In a mouse model of poor RBC storage, with elevated reactive oxygen species production, DLA attenuated lipid peroxidation and significantly improved RBC storage quality.

Biological and Clinical Factors Contributing to the Metabolic Heterogeneity of Hospitalized Patients with and without COVID-19

The Corona Virus Disease 2019 (COVID-19) pandemic represents an ongoing worldwide challenge. The present large study sought to understand independent and overlapping metabolic features of samples from acutely ill patients (n = 831) that tested positive (n = 543) or negative (n = 288) for COVID-19. High-throughput metabolomics analyses were complemented with antigen and enzymatic activity assays on plasma from acutely ill patients collected while in the emergency department, at admission, or during hospitalization. Lipidomics analyses were also performed on COVID-19-positive or -negative subjects with the lowest and highest body mass index (n = 60/group). Significant changes in amino acid and fatty acid/acylcarnitine metabolism emerged as highly relevant markers of disease severity, progression, and prognosis as a function of biological and clinical variables in these patients. Further, machine learning models were trained by entering all metabolomics and clinical data from half of the COVID-19 patient cohort and then tested on the other half, yielding ~78% prediction accuracy. Finally, the extensive amount of information accumulated in this large, prospective, observational study provides a foundation for mechanistic follow-up studies and data sharing opportunities, which will advance our understanding of the characteristics of the plasma metabolism in COVID-19 and other acute critical illnesses.

Hematologic and systemic metabolic alterations due to Mediterranean class II G6PD deficiency in mice

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) is the single most common enzymopathy, present in approximately 400 million humans (approximately 5%). Its prevalence is hypothesized to be due to conferring resistance to malaria. However, G6PD deficiency also results in hemolytic sequelae from oxidant stress. Moreover, G6PD deficiency is associated with kidney disease, diabetes, pulmonary hypertension, immunological defects, and neurodegenerative diseases. To date, the only available mouse models have decreased levels of WT stable G6PD caused by promoter mutations. However, human G6PD mutations are missense mutations that result in decreased enzymatic stability. As such, this results in very low activity in red blood cells (RBCs) that cannot synthesize new protein. To generate a more accurate model, the human sequence for a severe form of G6PD deficiency, Med(-), was knocked into the murine G6PD locus. As predicted, G6PD levels were extremely low in RBCs, and deficient mice had increased hemolytic sequelae to oxidant stress. Nonerythroid organs had metabolic changes consistent with mild G6PD deficiency, consistent with what has been observed in humans. Juxtaposition of G6PD-deficient and WT mice revealed altered lipid metabolism in multiple organ systems. Together, these findings both establish a mouse model of G6PD deficiency that more accurately reflects human G6PD deficiency and advance our basic understanding of altered metabolism in this setting.

Serum Proteomics in COVID-19 Patients: Altered Coagulation and Complement Status as a Function of IL-6 Level

Over 5 million people around the world have tested positive for the beta coronavirus SARS-CoV-2 as of May 29, 2020, a third of which are in the United States alone. These infections are associated with the development of a disease known as COVID-19, which is characterized by several symptoms, including persistent dry cough, shortness of breath, chills, muscle pain, headache, loss of taste or smell, and gastrointestinal distress. COVID-19 has been characterized by elevated mortality (over 100 thousand people have already died in the US alone), mostly due to thromboinflammatory complications that impair lung perfusion and systemic oxygenation in the most severe cases. While the levels of pro-inflammatory cytokines such as interleukin-6 (IL-6) have been associated with the severity of the disease, little is known about the impact of IL-6 levels on the proteome of COVID-19 patients. The present study provides the first proteomics analysis of sera from COVID-19 patients, stratified by circulating levels of IL-6, and correlated to markers of inflammation and renal function. As a function of IL-6 levels, we identified significant dysregulation in serum levels of various coagulation factors, accompanied by increased levels of antifibrinolytic components, including several serine protease inhibitors (SERPINs). These were accompanied by up-regulation of the complement cascade and antimicrobial enzymes, especially in subjects with the highest levels of IL-6, which is consistent with an exacerbation of the acute phase response in these subjects. Although our results are observational, they highlight a clear increase in the levels of inhibitory components of the fibrinolytic cascade in severe COVID-19 disease, providing potential clues related to the etiology of coagulopathic complications in COVID-19 and paving the way for potential therapeutic interventions, such as the use of pro-fibrinolytic agents. Raw data for this study are available through ProteomeXchange with identifier PXD020601.

Evidence of Structural Protein Damage and Membrane Lipid Remodeling in Red Blood Cells from COVID-19 Patients

The SARS-CoV-2 beta coronavirus is the etiological driver of COVID-19 disease, which is primarily characterized by shortness of breath, persistent dry cough, and fever. Because they transport oxygen, red blood cells (RBCs) may play a role in the severity of hypoxemia in COVID-19 patients. The present study combines state-of-the-art metabolomics, proteomics, and lipidomics approaches to investigate the impact of COVID-19 on RBCs from 23 healthy subjects and 29 molecularly diagnosed COVID-19 patients. RBCs from COVID-19 patients had increased levels of glycolytic intermediates, accompanied by oxidation and fragmentation of ankyrin, spectrin beta, and the N-terminal cytosolic domain of band 3 (AE1). Significantly altered lipid metabolism was also observed, in particular, short- and medium-chain saturated fatty acids, acyl-carnitines, and sphingolipids. Nonetheless, there were no alterations of clinical hematological parameters, such as RBC count, hematocrit, or mean corpuscular hemoglobin concentration, with only minor increases in mean corpuscular volume. Taken together, these results suggest a significant impact of SARS-CoV-2 infection on RBC structural membrane homeostasis at the protein and lipid levels. Increases in RBC glycolytic metabolites are consistent with a theoretically improved capacity of hemoglobin to off-load oxygen as a function of allosteric modulation by high-energy phosphate compounds, perhaps to counteract COVID-19-induced hypoxia. Conversely, because the N-terminus of AE1 stabilizes deoxyhemoglobin and finely tunes oxygen off-loading and metabolic rewiring toward the hexose monophosphate shunt, RBCs from COVID-19 patients may be less capable of responding to environmental variations in hemoglobin oxygen saturation/oxidant stress when traveling from the lungs to peripheral capillaries and vice versa.

ZOOMICS: Comparative Metabolomics of Red Blood Cells From Old World Monkeys and Humans

As part of the ZOOMICS project, we set out to investigate common and diverging metabolic traits in the blood metabolome across various species by taking advantage of recent developments in high-throughput metabolomics. Here we provide the first comparative metabolomics analysis of fresh and stored human (n = 21, 10 males, 11 females), olive baboon (n = 20), and rhesus macaque (n = 20) red blood cells at baseline and upon 42 days of storage under blood bank conditions. The results indicated similarities and differences across species, which ultimately resulted in a differential propensity to undergo morphological alterations and lyse as a function of the duration of refrigerated storage. Focusing on purine oxidation, carboxylic acid, fatty acid, and arginine metabolism further highlighted species-specific metabolic wiring. For example, through a combination of steady state measurements and ¹³C₆¹⁵N₄-arginine tracing experiments, we report an increase in arginine catabolism into ornithine in humans, suggestive of species-specific arginase 1 activity and nitric oxide synthesis—an observation that may impact the translatability of cardiovascular disease studies carried out in non-human primates (NHPs). Finally, we correlated metabolic measurements to storage-induced morphological alterations via scanning electron microscopy and hemolysis, which were significantly lower in human red cells compared to both NHPs.

Red blood cell metabolism in Rhesus macaques and humans: comparative biology of blood storage

Macaques are emerging as a critical animal model in transfusion medicine, because of their evolutionary similarity to humans and perceived utility in discovery and translational science. However, little is known about the metabolism of Rhesus macaque red blood cells (RBC) and how this compares to human RBC metabolism under standard blood banking conditions. Metabolomic and lipidomic analyses, and tracing experiments with [1,2,3-¹³C₃]glucose, were performed using fresh and stored RBC (sampled weekly until storage day 42) obtained from Rhesus macaques (n=20) and healthy human volunteers (n=21). These results were further validated with targeted quantification against stable isotope-labeled internal standards. Metabolomic analyses demonstrated inter-species differences in RBC metabolism independent of refrigerated storage. Although similar trends were observed throughout storage for several metabolic pathways, species- and sex-specific differences were also observed. The most notable differences were in glutathione and sulfur metabolites, purine and lipid oxidation metabolites, acylcarnitines, fatty acyl composition of several classes of lipids (including phosphatidylserines), glyoxylate pathway intermediates, and arginine and carboxylic acid metabolites. Species-specific dietary and environmental compounds were also detected. Overall, the results suggest an increased basal and refrigerator-storage-induced propensity for oxidant stress and lipid remodeling in Rhesus macaque RBC cells, as compared to human red cells. The overlap between Rhesus macaque and human RBC metabolic phenotypes suggests the potential utility of a translational model for simple RBC transfusions, although inter-species storage-dependent differences need to be considered when modeling complex disease states, such as transfusion in trauma/hemorrhagic shock models.

COVID-19 infection alters kynurenine and fatty acid metabolism, correlating with IL-6 levels and renal status

BACKGROUNDReprogramming of host metabolism supports viral pathogenesis by fueling viral proliferation, by providing, for example, free amino acids and fatty acids as building blocks.METHODSTo investigate metabolic effects of SARS-CoV-2 infection, we evaluated serum metabolites of patients with COVID-19 (n = 33; diagnosed by nucleic acid testing), as compared with COVID-19-negative controls (n = 16).RESULTSTargeted and untargeted metabolomics analyses identified altered tryptophan metabolism into the kynurenine pathway, which regulates inflammation and immunity. Indeed, these changes in tryptophan metabolism correlated with interleukin-6 (IL-6) levels. Widespread dysregulation of nitrogen metabolism was also seen in infected patients, with altered levels of most amino acids, along with increased markers of oxidant stress (e.g., methionine sulfoxide, cystine), proteolysis, and renal dysfunction (e.g., creatine, creatinine, polyamines). Increased circulating levels of glucose and free fatty acids were also observed, consistent with altered carbon homeostasis. Interestingly, metabolite levels in these pathways correlated with clinical laboratory markers of inflammation (i.e., IL-6 and C-reactive protein) and renal function (i.e., blood urea nitrogen).CONCLUSIONIn conclusion, this initial observational study identified amino acid and fatty acid metabolism as correlates of COVID-19, providing mechanistic insights, potential markers of clinical severity, and potential therapeutic targets.FUNDINGBoettcher Foundation Webb-Waring Biomedical Research Award; National Institute of General and Medical Sciences, NIH; and National Heart, Lung, and Blood Institute, NIH.

Evidence for structural protein damage and membrane lipid remodeling in red blood cells from COVID-19 patients

The SARS-CoV-2 beta coronavirus is the etiological driver of COVID-19 disease, which is primarily characterized by shortness of breath, persistent dry cough, and fever. Because they transport oxygen, red blood cells (RBCs) may play a role in the severity of hypoxemia in COVID-19 patients. The present study combines state-of-the-art metabolomics, proteomics, and lipidomics approaches to investigate the impact of COVID-19 on RBCs from 23 healthy subjects and 29 molecularly-diagnosed COVID-19 patients. RBCs from COVID-19 patients had increased levels of glycolytic intermediates, accompanied by oxidation and fragmentation of ankyrin, spectrin beta, and the N-terminal cytosolic domain of band 3 (AE1). Significantly altered lipid metabolism was also observed, especially short and medium chain saturated fatty acids, acyl-carnitines, and sphingolipids. Nonetheless, there were no alterations of clinical hematological parameters, such as RBC count, hematocrit, and mean corpuscular hemoglobin concentration, with only minor increases in mean corpuscular volume. Taken together, these results suggest a significant impact of SARS-CoV-2 infection on RBC structural membrane homeostasis at the protein and lipid levels. Increases in RBC glycolytic metabolites are consistent with a theoretically improved capacity of hemoglobin to off-load oxygen as a function of allosteric modulation by high-energy phosphate compounds, perhaps to counteract COVID-19-induced hypoxia. Conversely, because the N-terminus of AE1 stabilizes deoxyhemoglobin and finely tunes oxygen off-loading, RBCs from COVID-19 patients may be incapable of responding to environmental variations in hemoglobin oxygen saturation when traveling from the lungs to peripheral capillaries and, as such, may have a compromised capacity to transport and deliver oxygen.

COVID-19 infection results in alterations of the kynurenine pathway and fatty acid metabolism that correlate with IL-6 levels and renal status

Previous studies suggest a role for systemic reprogramming of host metabolism during viral pathogenesis to fuel rapidly expanding viral proliferation, for example by providing free amino acids and fatty acids as building blocks. In addition, general alterations in metabolism can provide key understanding of pathogenesis. However, little is known about the specific metabolic effects of SARS-COV-2 infection. The present study evaluated the serum metabolism of COVID-19 patients (n=33), identified by a positive nucleic acid test of a nasopharyngeal swab, as compared to COVID-19-negative control patients (n=16). Targeted and untargeted metabolomics analyses specifically identified alterations in the metabolism of tryptophan into the kynurenine pathway, which is well-known to be involved in regulating inflammation and immunity. Indeed, the observed changes in tryptophan metabolism correlated with serum interleukin-6 (IL-6) levels. Metabolomics analysis also confirmed widespread dysregulation of nitrogen metabolism in infected patients, with decreased circulating levels of most amino acids, except for tryptophan metabolites in the kynurenine pathway, and increased markers of oxidant stress (e.g., methionine sulfoxide, cystine), proteolysis, and kidney dysfunction (e.g., creatine, creatinine, polyamines). Increased circulating levels of glucose and free fatty acids were also observed, consistent with altered carbon homeostasis in COVID-19 patients. Metabolite levels in these pathways correlated with clinical laboratory markers of inflammation and disease severity (i.e., IL-6 and C-reactive protein) and renal function (i.e., blood urea nitrogen). In conclusion, this initial observational study of the metabolic consequences of COVID-19 infection in a clinical cohort identified amino acid metabolism (especially kynurenine and cysteine/taurine) and fatty acid metabolism as correlates of COVID-19, providing mechanistic insights, potential markers of clinical severity, and potential therapeutic targets.

Functional Coagulation Differences Between Lobar and Deep Intracerebral Hemorrhage Detected by Rotational Thromboelastometry: A Pilot Study

BACKGROUND

Lobar intracerebral hemorrhage (ICH) is known to have better clinical outcomes and preliminary evidence of less hematoma expansion compared to deep ICH. No functional coagulation differences between lobar and deep ICH have been identified using traditional plasma-based coagulation tests. We investigated for coagulation differences between lobar and deep ICH using whole-blood coagulation testing (Rotational Thromboelastometry: [ROTEM]).

METHODS

Clinical, radiographic, and laboratory data were prospectively collected for primary ICH patients enrolled in a single-center ICH study. Patients with preceding anticoagulant use or admission coagulopathy on traditional laboratory testing were excluded. Lobar and deep ICH patients receiving admission ROTEM were analyzed. Linear regression was used to assess the association of ICH location with coagulation test results after adjusting for potential confounders.

RESULTS

There were 12 lobar and 19 deep ICH patients meeting inclusion criteria. Lobar ICH patients were significantly older and predominantly female. Lobar ICH had faster intrinsic pathway coagulation times (139.8 vs 203.2 s; 95% CI - 179.91 to - 45.96; p = 0.002) on ROTEM testing compared to deep ICH after adjusting for age, sex, and hematoma volume. This revealed functional coagulation differences, specifically quicker clot formation in lobar compared to deep ICH. No differences were noted using traditional coagulation testing (prothrombin time/partial thromboplastin time/platelet count).

CONCLUSIONS

Our pilot data may suggest that there are functional coagulation differences between lobar and deep ICH identified using ROTEM. Whole-blood coagulation testing may be useful in assessing coagulopathy in ICH patients and in determining reversal treatment paradigms, though further work is needed.

ABO Blood Type and Hematoma Expansion After Intracerebral Hemorrhage: An Exploratory Analysis

BACKGROUND/PURPOSE

Blood type has become an increasingly recognized risk factor for coagulopathy. We explored the association between blood type and hematoma expansion (HE) after intracerebral hemorrhage (ICH).

METHODS

Spontaneous ICH patients prospectively enrolled in an ongoing ICH cohort study at Columbia University Irving Medical Center from 2009 to 2016 were evaluated. Primary ICH patients with admission blood type testing were evaluated for HE differences, defined as > 33% relative HE. The association of blood type with radiographic HE outcomes was assessed using multivariable logistic regression models. The association of blood type and poor clinical outcomes using modified Rankin Scale (mRS 4-6) was additionally explored.

RESULTS

Of 272 ICH patients with blood type data and neuroimaging available to determine HE, there were 146 (54%) type-O, 82 (30%) type-A, 34 (13%) type-B, and 10 (3%) type-AB patients. No significant baseline demographic, clinical, or radiographic differences were noted between blood types. Type-B blood was associated with more HE compared to other blood types (OR 2.82; 95% CI 1.23-6.45) after adjusting for known covariates of HE (anticoagulant use, time to admission computed tomography scan, and baseline hematoma volume). No associations with blood type and poor 3 month mRS were identified, but these analyses were limited secondary to our smaller cohort.

CONCLUSIONS

There may be differences in HE after ICH in patients with different blood types. Further work is required to replicate these findings and identify the pathophysiologic mechanisms behind coagulopathy between blood types after ICH.

Donor glucose-6-phosphate dehydrogenase deficiency decreases blood quality for transfusion

BACKGROUNDGlucose-6-phosphate dehydrogenase (G6PD) deficiency decreases the ability of red blood cells (RBCs) to withstand oxidative stress. Refrigerated storage of RBCs induces oxidative stress. We hypothesized that G6PD-deficient donor RBCs would have inferior storage quality for transfusion as compared with G6PD-normal RBCs.METHODSMale volunteers were screened for G6PD deficiency; 27 control and 10 G6PD-deficient volunteers each donated 1 RBC unit. After 42 days of refrigerated storage, autologous 51-chromium 24-hour posttransfusion RBC recovery (PTR) studies were performed. Metabolomics analyses of these RBC units were also performed.RESULTSThe mean 24-hour PTR for G6PD-deficient subjects was 78.5% ± 8.4% (mean ± SD), which was significantly lower than that for G6PD-normal RBCs (85.3% ± 3.2%; P = 0.0009). None of the G6PD-normal volunteers (0/27) and 3 G6PD-deficient volunteers (3/10) had PTR results below 75%, a key FDA acceptability criterion for stored donor RBCs. As expected, fresh G6PD-deficient RBCs demonstrated defects in the oxidative phase of the pentose phosphate pathway. During refrigerated storage, G6PD-deficient RBCs demonstrated increased glycolysis, impaired glutathione homeostasis, and increased purine oxidation, as compared with G6PD-normal RBCs. In addition, there were significant correlations between PTR and specific metabolites in these pathways.CONCLUSIONBased on current FDA criteria, RBCs from G6PD-deficient donors would not meet the requirements for storage quality. Metabolomics assessment identified markers of PTR and G6PD deficiency (e.g., pyruvate/lactate ratios), along with potential compensatory pathways that could be leveraged to ameliorate the metabolic needs of G6PD-deficient RBCs.TRIAL REGISTRATIONClinicalTrials.gov NCT04081272.FUNDINGThe Harold Amos Medical Faculty Development Program, Robert Wood Johnson Foundation grant 71590, the National Blood Foundation, NIH grant UL1 TR000040, the Webb-Waring Early Career Award 2017 by the Boettcher Foundation, and National Heart, Lung, and Blood Institute grants R01HL14644 and R01HL148151.

Reexamination of the chromium-51-labeled posttransfusion red blood cell recovery method

BACKGROUND

The chromium-51-labeled posttransfusion recovery (PTR) study has been the gold-standard test for assessing red blood cell (RBC) quality. Despite guiding RBC storage development for decades, it has several potential sources for error.

METHODS

Four healthy adult volunteers each donated an autologous, leukoreduced RBC unit, aliquots were radiolabeled with technetium-99m after 1 and 6 weeks of storage, and then infused. Subjects were imaged by single-photon-emission computed tomography immediately and 4 hours after infusion. Additionally, from subjects described in a previously published study, adenosine triphosphate levels in transfusates infused into 52 healthy volunteers randomized to a single autologous, leukoreduced, RBC transfusion after 1, 2, 3, 4, 5, or 6 weeks of storage were correlated with PTR and laboratory parameters of hemolysis.

RESULTS

Evidence from one subject imaged after infusion of technetium-99m-labeled RBCs suggests that, in some individuals, RBCs may be temporarily sequestered in the liver and spleen immediately following transfusion and then subsequently released back into circulation; this could be one source of error leading to PTR results that may not accurately predict the true quantity of RBCs cleared by intra- and/or extravascular hemolysis. Indeed, adenosine triphosphate levels in the transfusates correlated more robustly with measures of extravascular hemolysis in vivo (e.g., serum iron, indirect bilirubin, non-transferrin-bound iron) than with PTR results or measures of intravascular hemolysis (e.g., plasma free hemoglobin).

CONCLUSIONS

Sources of measurement error are inherent in the chromium-51 PTR method. Transfusion of an entire unlabeled RBC unit, followed by quantifying extravascular hemolysis markers, may more accurately measure true posttransfusion RBC recovery.

Glucose-6-phosphate-dehydrogenase deficient red blood cell units are associated with decreased posttransfusion red blood cell survival in children with sickle cell disease

Chronic transfusion therapy (CTT) for sickle cell disease (SCD) reduces disease morbidity by suppressing the amount of circulating hemoglobin S (HbS)-containing red blood cells (RBC). The effectiveness of CTT depends on the rate of RBC clearance. Glucose-6-phosphate dehydrogenase (G6PD) deficient donor RBC may exhibit increased hemolysis, but it is unknown if transfusion of these units results in less effective transfusion outcomes in SCD. Children with SCD on CTT were followed prospectively for multiple transfusions. G6PD activity of transfused units was measured prior to expiration date. HbA clearance (ΔHbA) was calculated as the difference of estimated posttransfusion HbA to the pretransfusion HbA of the subsequent transfusion episode. Sixty-two patients received 388 transfusions. Of 755 RBC units, 687 (91%) had normal G6PD (>60% activity), 38 (5%) had moderately low G6PD (10-60% activity), and 30 (4%) had severely low G6PD (<10% activity). Of 358 evaluable transfusions, 54 (15%) included ≥1 G6PD deficient units, and 22 (6%) had ≥1 severely deficient units. The proportion of the transfusion episode consisting of G6PD deficient units was associated with increased ΔHbA for all G6PD deficient units (P = .05) and for severely G6PD deficient units (P = .0070). In multivariate mixed effects modeling, ΔHbA was positively associated with severely G6PD deficient units (P = .0074) and RBC alloimmunization (P = .03) and negatively associated with recipient splenectomy (P = .015). Higher ΔHbA was associated with higher HbS and reticulocyte counts at the subsequent transfusion episode. In conclusion, G6PD deficient RBC transfusions may have shorter in vivo survival and adversely affect the suppression of sickle erythropoiesis.

Hypoxia modulates the purine salvage pathway and decreases red blood cell and supernatant levels of hypoxanthine during refrigerated storage

Hypoxanthine catabolism in vivo is potentially dangerous as it fuels production of urate and, most importantly, hydrogen peroxide. However, it is unclear whether accumulation of intracellular and supernatant hypoxanthine in stored red blood cell units is clinically relevant for transfused recipients. Leukoreduced red blood cells from glucose-6-phosphate dehydrogenase-normal or -deficient human volunteers were stored in AS-3 under normoxic, hyperoxic, or hypoxic conditions (with oxygen saturation ranging from <3% to >95%). Red blood cells from healthy human volunteers were also collected at sea level or after 1–7 days at high altitude (>5000 m). Finally, C57BL/6J mouse red blood cells were incubated in vitro with ¹³C₁-aspartate or ¹³C₅-adenosine under normoxic or hypoxic conditions, with or without deoxycoformycin, a purine deaminase inhibitor. Metabolomics analyses were performed on human and mouse red blood cells stored for up to 42 or 14 days, respectively, and correlated with 24 h post-transfusion red blood cell recovery. Hypoxanthine increased in stored red blood cell units as a function of oxygen levels. Stored red blood cells from human glucose-6-phosphate dehydrogenase-deficient donors had higher levels of deaminated purines. Hypoxia in vitro and in vivo decreased purine oxidation and enhanced purine salvage reactions in human and mouse red blood cells, which was partly explained by decreased adenosine monophosphate deaminase activity. In addition, hypoxanthine levels negatively correlated with post-transfusion red blood cell recovery in mice and – preliminarily albeit significantly - in humans. In conclusion, hypoxanthine is an in vitro metabolic marker of the red blood cell storage lesion that negatively correlates with post-transfusion recovery in vivo. Storage-dependent hypoxanthine accumulation is ameliorated by hypoxia-induced decreases in purine deamination reaction rates.

How do we perform and bill for blood bank physician consultative services?

Transfusion medicine (TM) physicians provide medical services that benefit all patients such as providing 24-hour laboratory coverage, advising health care providers on test interpretation and selection, validating new methods, and supervising technical personnel. These services ensure delivery of accurate, reliable, and timely laboratory test results and blood products. TM physicians also provide consultations to individual patients by 1) interpreting and determining the clinical significance of test results (e.g., alloantibodies, direct antiglobulin tests), 2) recommending appropriate component therapy and approving deviations from laboratory policy, and 3) evaluating and recommending treatment of suspected transfusion reactions. The potential benefits of consultations are improved quality and cost of health care, enhanced provider education, and decreased inappropriate testing and product utilization. When physician services are delivered to individual patients, are appropriately requested, provide a diagnosis or recommendation, and are properly documented, TM physicians can receive professional reimbursement. While many TM physicians provide medical direction and oversight of apheresis procedures, billing in this area is sufficiently complex to be reviewed elsewhere. The objective of this article is for educational purposes to describe the 1) benefits of a consultative TM service, 2) development of reimbursement systems in the United States for professional component services and the current regulatory requirements, 3) current procedural terminology codes commonly used for TM physician services, and 4) examples of consultation documentation and daily workflow at tertiary care teaching hospitals. The information provided should help guide physicians to deliver and bill for these services.

Prolonged red cell storage before transfusion increases extravascular hemolysis

BACKGROUND

Some countries have limited the maximum allowable storage duration for red cells to 5 weeks before transfusion. In the US, red blood cells can be stored for up to 6 weeks, but randomized trials have not assessed the effects of this final week of storage on clinical outcomes.

METHODS

Sixty healthy adult volunteers were randomized to a single standard, autologous, leukoreduced, packed red cell transfusion after 1, 2, 3, 4, 5, or 6 weeks of storage (n = 10 per group). 51-Chromium posttransfusion red cell recovery studies were performed and laboratory parameters measured before and at defined times after transfusion.

RESULTS

Extravascular hemolysis after transfusion progressively increased with increasing storage time (P < 0.001 for linear trend in the AUC of serum indirect bilirubin and iron levels). Longer storage duration was associated with decreasing posttransfusion red cell recovery (P = 0.002), decreasing elevations in hematocrit (P = 0.02), and increasing serum ferritin (P < 0.0001). After 6 weeks of refrigerated storage, transfusion was followed by increases in AUC for serum iron (P < 0.01), transferrin saturation (P < 0.001), and nontransferrin-bound iron (P < 0.001) as compared with transfusion after 1 to 5 weeks of storage.

CONCLUSIONS

After 6 weeks of refrigerated storage, transfusion of autologous red cells to healthy human volunteers increased extravascular hemolysis, saturated serum transferrin, and produced circulating nontransferrin-bound iron. These outcomes, associated with increased risks of harm, provide evidence that the maximal allowable red cell storage duration should be reduced to the minimum sustainable by the blood supply, with 35 days as an attainable goal.REGISTRATION. ClinicalTrials.gov NCT02087514.

FUNDING

NIH grant HL115557 and UL1 TR000040.

Red blood cell components: Meeting the quantitative and qualitative transfusion needs

Red blood cell (RBC) transfusion is a very common therapeutic intervention. However, because of multiple recent studies improving our understanding of appropriate transfusion scenarios, the total number of RBC units transfused per year is actually decreasing in the developed world and there are no longer major shortages of RBC products for general use. Nonetheless, there are an increasing number of "special" uses, which can put strains on the blood supply for particular types of products; these may produce shortages of specific types of RBCs or require collections targeting certain types of donors. This review will focus on several broad topics, including providing some examples of "special" settings that require, or could require, special types of RBC products.

Diagnosis of a rare fetal haemoglobinopathy in the age of next-generation sequencing

Neonatal cyanosis resulting from a fetal methaemoglobin variant is rare. Most such variants are only described in a few published case reports. We present the case of a newborn with unexplained persistent cyanosis, ultimately determined to have a γ-chain mutation causing Hb FM-Fort Ripley. This neonatal haemoglobinopathy can be challenging to diagnose, as significant oxygen desaturation may result from barely detectable levels of the mutant haemoglobin and co-oximetry studies may show a falsely normal methaemoglobin level. Our analysis of the infant's haemoglobin included high-performance liquid chromatography, cellulose acetate electrophoresis and citrate agar electrophoresis, which showed trace amounts of a suspected variant. Ultimately, the diagnosis was made through a novel application of next-generation sequencing (NGS). NGS-based diagnostic approaches are becoming increasingly available to clinicians, and our case provides a framework and evidence for the utilisation of such testing paradigms in the diagnosis of a rare cause of neonatal cyanosis.

Red blood cell transfusion is associated with increased hemolysis and an acute phase response in a subset of critically ill children

In healthy adults, transfusion of older stored red blood cells (RBCs) produces extravascular hemolysis and circulating non-transferrin-bound iron. In a prospective, observational study of critically ill children, we examined the effect of RBC storage duration on the extent of hemolysis by comparing laboratory measurements obtained before, and 4 hr after, RBC transfusion (N = 100) or saline/albumin infusion (N = 20). Transfusion of RBCs stored for longer than 4 weeks significantly increased plasma free hemoglobin (P < 0.05), indirect bilirubin (P < 0.05), serum iron (P < 0.001), and non-transferrin-bound iron (P < 0.01). However, days of storage duration poorly correlated (R(2) <0.10) with all measured indicators of hemolysis and inflammation. These results suggest that, in critically ill children, most effects of RBC storage duration on post-transfusion hemolysis are overwhelmed by recipient and/or donor factors. Nonetheless, we identified a subset of patients (N = 21) with evidence of considerable extravascular hemolysis (i.e., increased indirect bilirubin ≥0.4 mg/dL). In these patients, transfusion-associated hemolysis was accompanied by increases in circulating non-transferrin-bound iron and free hemoglobin and by an acute phase response, as assessed by an increase in median C-reactive protein levels of 21.2 mg/L (P < 0.05). In summary, RBC transfusions were associated with an acute phase response and both extravascular and intravascular hemolysis, which were independent of RBC storage duration. The 21% of transfusions that were associated with substantial hemolysis conferred an increased risk of inducing an acute phase response.

G6PD Deficiency in an HIV Clinic Setting in the Dominican Republic

Because human immunodeficiency virus (HIV)-infected patients receive prophylaxis with oxidative drugs, those with glucose-6-phosphate dehydrogenase (G6PD) deficiency may experience hemolysis. However, G6PD deficiency has not been studied in the Dominican Republic, where many individuals have African ancestry. Our objective was to determine the prevalence of G6PD deficiency in Dominican HIV-infected patients and to attempt to develop a cost-effective algorithm for identifying such individuals. To this end, histories, chart reviews, and G6PD testing were performed for 238 consecutive HIV-infected adult clinic patients. The overall prevalence of G6PD deficiency (8.8%) was similar in males (9.3%) and females (8.5%), and higher in Haitians (18%) than Dominicans (6.4%; P = 0.01). By logistic regression, three clinical variables predicted G6PD status: maternal country of birth (P = 0.01) and a history of hemolysis (P = 0.01) or severe anemia (P = 0.03). Using these criteria, an algorithm was developed, in which a patient subset was identified that would benefit most from G6PD screening, yielding a sensitivity of 94.7% and a specificity of 97.2%, increasing the pretest probability (8.8-15.1%), and halving the number of patients needing testing. This algorithm may provide a cost-effective strategy for improving care in resource-limited settings.

Macrophages clear refrigerator storage-damaged red blood cells and subsequently secrete cytokines in vivo, but not in vitro, in a murine model

BACKGROUND

In mice, refrigerator-stored red blood cells (RBCs) are cleared by extravascular hemolysis and induce cytokine production. To enhance understanding of this phenomenon, we sought to model it in vitro.

STUDY DESIGN AND METHODS

Ingestion of refrigerator-stored murine RBCs and subsequent cytokine production were studied using J774A.1 mouse macrophage cells and primary murine splenic macrophages. Wild-type and Ccl2-GFP reporter mice were used for RBC clearance in vivo.

RESULTS

Although J774A.1 cells and primary macrophages preferentially ingested refrigerator-stored RBCs in vitro, compared to freshly isolated RBCs, neither produced increased cytokines after erythrophagocytosis. In contrast, phagocytosis of refrigerator-stored RBCs in vivo induced increases in circulating monocyte chemoattractant protein-1 (MCP-1) and keratinocyte chemoattractant (KC) and correspondingly increased mRNA levels in mouse spleen and liver. In the spleen, these were predominantly expressed by CD11b+ cells. Using Ccl2-GFP reporter mice, the predominant splenic population responsible for MCP-1 mRNA production was tissue-resident macrophages (i.e., CD45+, CD11b+, F4/80+, Ly6c+, and CD11c(low) cells).

CONCLUSION

J774A.1 cells and primary macrophages selectively ingested refrigerator-stored RBCs by phagocytosis. Although cytokine expression was not enhanced, this approach could be used to identify the relevant receptor-ligand combination(s). In contrast, cytokine levels increased after phagocytosis of refrigerator-stored RBCs in vivo. These were primarily cleared in the liver and spleen, which demonstrated increased MCP-1 and KC mRNA expression. Finally, in mouse spleen, tissue-resident macrophages were predominantly involved in MCP-1 mRNA production. The differences between cytokine production in vitro and in vivo are not yet well understood.

Transfusion of stored blood impairs host defenses against Gram-negative pathogens in mice

BACKGROUND

Although human red blood cell (RBC) units may be refrigerator stored for up to 42 days, transfusion of older RBCs acutely delivers a large bolus of iron to mononuclear phagocytes. Similarly, iron dextran circulates in plasma for hours to days and is progressively cleared by mononuclear phagocytes, which return iron to plasma. Finally, malaria infection continuously delivers iron to macrophages by intra- and extravascular hemolysis. Studies suggest that iron administration increases infectious risk.

STUDY DESIGN AND METHODS

To assess the effects of increased iron availability on susceptibility to infection, we infected mice with model Gram-negative intracellular or extracellular pathogens (Salmonella typhimurium or Escherichia coli, respectively), accompanied by RBC transfusion, iron dextran administration, or malarial coinfection.

RESULTS

In our mouse models, transfusion of older RBCs exacerbates infection with both Gram-negative pathogens. Although iron dextran exacerbates E. coli infection to a similar extent as transfusion of corresponding amounts of iron, higher iron doses are required to produce comparable effects with S. typhimurium. Coinfection of mice with Plasmodium yoelii and S. typhimurium produces overwhelming Salmonella sepsis. Finally, treating mice with antibiotics abrogates the enhancing effect on E. coli infection of both older RBC transfusion and iron dextran administration.

CONCLUSIONS

Transfusion of older RBCs exacerbates Gram-negative infection to a similar extent as malaria coinfection or iron dextran administration. Appropriate antibiotic therapy abrogates the effect of older RBC transfusions on infection with E. coli. Iron delivery to macrophages may be an underappreciated mechanism mediating, at least some, adverse effects of RBC transfusions.

Glucose-6-phosphate dehydrogenase deficiency in transfusion medicine: the unknown risks

The hallmark of glucose-6-phosphate dehydrogenase (G6PD) deficiency is red blood cell (RBC) destruction in response to oxidative stress. Patients requiring RBC transfusions may simultaneously receive oxidative medications or have concurrent infections, both of which can induce haemolysis in G6PD-deficient RBCs. Although it is not routine practice to screen healthy blood donors for G6PD deficiency, case reports identified transfusion of G6PD-deficient RBCs as causing haemolysis and other adverse events. In addition, some patient populations may be more at risk for complications associated with transfusions of G6PD-deficient RBCs because they receive RBCs from donors who are more likely to have G6PD deficiency. This review discusses G6PD deficiency, its importance in transfusion medicine, changes in the RBC antioxidant system (of which G6PD is essential) during refrigerated storage and mechanisms of haemolysis. In addition, as yet unanswered questions that could be addressed by translational and clinical studies are identified and discussed.

Strain-specific red blood cell storage, metabolism, and eicosanoid generation in a mouse model

BACKGROUND

Red blood cell (RBC) transfusion is a lifesaving therapy, the logistic implementation of which requires RBC storage. However, stored RBCs exhibit substantial donor variability in multiple characteristics, including hemolysis in vitro and RBC recovery in vivo. The basis of donor variability is poorly understood.

STUDY DESIGN AND METHODS

We applied a murine model of RBC storage and transfusion to test the hypothesis that genetically distinct inbred strains of mice would demonstrate strain-specific differences in RBC storage. In vivo recoveries were determined by monitoring transfused RBCs over 24 hours. Timed aliquots of stored RBCs were subjected to tandem chromatography/mass spectrometry analysis to elucidate metabolic changes in the RBCs during storage.

RESULTS

Using independent inbred mouse strains as donors, we found substantial strain-specific differences in posttransfusion RBC recovery in vivo after standardized refrigerated storage in vitro. Poor posttransfusion RBC recovery correlated with reproducible metabolic variations in the stored RBC units, including increased lipid peroxidation, decreased levels of multiple natural antioxidants, and accumulation of cytidine. Strain-dependent differences were also observed in eicosanoid generation (i.e., prostaglandins and leukotrienes).

CONCLUSION

These findings provide the first evidence of strain-specific metabolomic differences after refrigerated storage of murine RBCs. They also provide the first definitive biochemical evidence for strain-specific variation of eicosanoid generation during RBC storage. The molecules described that correlate with RBC storage quality, and their associated biochemical pathways, suggest multiple causal hypotheses that can be tested regarding predicting the quality of RBC units before transfusion and developing methods of improved RBC storage.

Acquired hemoglobin variants and exposure to glucose-6-phosphate dehydrogenase deficient red blood cell units during exchange transfusion for sickle cell disease in a patient requiring antigen-matched blood

Red blood cell exchange (RBCEx) is frequently used in the management of patients with sickle cell disease (SCD) and acute chest syndrome or stroke, or to maintain target hemoglobin S (HbS) levels. In these settings, RBCEx is a category I or II recommendation according to guidelines on the use of therapeutic apheresis published by the American Society for Apheresis. Matching donor red blood cells (RBCs) to recipient phenotypes (e.g., C, E, K-antigen negative) can decrease the risk of alloimmunization in patients with multi-transfused SCD. However, this may select for donors with a higher prevalence of RBC disorders for which screening is not performed. This report describes a patient with SCD treated with RBCEx using five units negative for C, E, K, Fya, Fyb (prospectively matched), four of which were from donors with hemoglobin variants and/or glucose-6-phosphate dehydrogenase (G6PD) deficiency. Pre-RBCEx HbS quantification by high performance liquid chromatography (HPLC) demonstrated 49.3% HbS and 2.8% hemoglobin C, presumably from transfusion of a hemoglobin C-containing RBC unit during a previous RBCEx. Post-RBCEx HPLC showed the appearance of hemoglobin G-Philadelphia. Two units were G6PD-deficient. The patient did well, but the consequences of transfusing RBC units that are G6PD-deficient and contain hemoglobin variants are unknown. Additional studies are needed to investigate effects on storage, in-vivo RBC recovery and survival, and physiological effects following transfusion of these units. Post-RBCEx HPLC can monitor RBCEx efficiency and detect the presence of abnormal transfused units.

Frequency of glucose-6-phosphate dehydrogenase-deficient red blood cell units in a metropolitan transfusion service

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is characterized by red blood cell (RBC) destruction in response to oxidative stress. Although blood donors are not routinely screened for G6PD deficiency, the transfusion of stored G6PD-deficient RBCs may have serious adverse outcomes. By measuring G6PD enzyme activity of RBC units from a large metropolitan hospital transfusion service, we sought to determine 1) the prevalence of G6PD-deficient RBC units, 2) if G6PD activity changes during storage, and 3) if G6PD activity in segments correlates with its activity in the bags.

STUDY DESIGN AND METHODS

Quantitative G6PD activity was measured in 301 randomly selected RBC units and 73 D+C-E- (i.e., R r or R R ) RBC units, all stored in additive solutions. G6PD deficiency was defined as activity less than 60% of the normal mean.

RESULTS

The frequency of G6PD-deficient units in the general inventory was 0.3% (1/301; 95% confidence interval [CI], <0.01%-2.1%). In contrast, its frequency in D+C-E- RBC units was 12.3% (9/73; 95% CI, 6.4%-22.0%). G6PD activity did not significantly change during the 42-day storage period, and G6PD activity measured in RBC storage bags and attached segments correlated well (r=0.7-0.9, p ≤ 0.001, Spearman rank correlation).

CONCLUSIONS

Although the frequency of G6PD-deficient RBC units in the transfusion service general inventory was relatively low, it was significantly higher among a subset of R r or R R units. The latter are preferentially allocated for transfusion to patients with sickle cell disease to decrease the risk of RBC alloimmunization, possibly allowing more of these units to be inadvertently targeted to these patients.

West Nile virus infection in blood donors in the New York City area during the 2010 seasonal epidemic

BACKGROUND

A uniform threshold strategy for converting from minipool (MP)-nucleic acid testing (NAT) to individual donation (ID)-NAT screening for acute West Nile virus (WNV) infection among blood donors is lacking. We report on WNV screening at the New York Blood Center during the 2010 seasonal WNV epidemic, the most severe epidemic in that state since the original outbreak in 1999.

STUDY DESIGN AND METHODS

Between July 1 and October 31, 2010, blood donations were screened by MP-NAT or ID-NAT and the presence of anti-WNV immunoglobulin (Ig)M and IgG was evaluated among NAT-positive donations.

RESULTS

Twenty presumed viremic donations were identified for a frequency of 0.0129% (1 in 7752 donations). Nine donations that could have been missed by MP-NAT were identified. Two of these donations were both IgM and IgG negative, one of which would have been missed if more than one positive donation was required for initiating ID-NAT. Retrospective ID-NAT revealed two positive donations. The majority of the NAT-positive donations in New York (16/19) were from donors who lived in counties that had the highest incidence of human WNV cases in the state.

CONCLUSION

Our data details the identification of WNV NAT-positive blood donations during a severe seasonal epidemic in the New York area. By initiating ID-NAT after one positive donation, using retrospective testing, and triggering ID-NAT regionally, we were able to prevent the release of presumably infectious donations. The detection of NAT-positive donations with retrospective testing, however, may indicate the need for changes in our trigger criteria.

Rapid detection of Klebsiella pneumoniae carbapenemase genes in enterobacteriaceae directly from blood culture bottles by real-time PCR

Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae are endemic in New York City hospitals and have been associated with serious infections globally. A real-time polymerase chain reaction (RT-PCR) assay was developed to detect carbapenem resistance attributable to KPC from blood culture bottles positive for gram-negative bacilli. Culture confirmation of carbapenemase production included automated imipenem and meropenem susceptibility testing and ertapenem susceptibility testing by disk-diffusion. A total of 323 Enterobacteriaceae isolates were tested, of which 8.7% (n = 28) demonstrated carbapenem-resistance by automated and manual susceptibility testing methods or by RT-PCR. The sensitivity, specificity, and positive and negative predictive values of the RT-PCR assay when compared with the automated method were 92.9%, 99.3%, 92.9%, and 99.3%, respectively, and 96.4%, 99.7%, 96.4%, and 99.7%, respectively, when compared with the ertapenem disk-diffusion method. RT-PCR is a rapid and reliable means of detecting carbapenem resistance due to KPC-plasmids in Enterobacteriaceae directly from blood culture bottles.

Use of mouse models to study the mechanisms and consequences of RBC clearance

Mice provide tractable animal models for studying the pathophysiology of various human disorders. This review discusses the use of mouse models for understanding red-blood-cell (RBC) clearance. These models provide important insights into the pathophysiology of various clinically relevant entities, such as autoimmune haemolytic anaemia, haemolytic transfusion reactions, other complications of RBC transfusions and immunomodulation by Rh immune globulin therapy. Mouse models of both antibody- and non-antibody-mediated RBC clearance are reviewed. Approaches for exploring unanswered questions in transfusion medicine using these models are also discussed.

Rb induces a proliferative arrest and curtails Brn-2 expression in retinoblastoma cells

BACKGROUND

Retinoblastoma is caused by loss of the Rb protein in early retinal cells. Although numerous Rb functions have been identified, Rb effects that specifically relate to the suppression of retinoblastoma have not been defined.

RESULTS

In this study, we examined the effects of restoring Rb to Y79 retinoblastoma cells, using novel retroviral and lentiviral vectors that co-express green fluorescent protein (GFP). The lentiviral vector permitted transduction with sufficient efficiency to perform biochemical analyses. Wild type Rb (RbWT) and to a lesser extent the low penetrance mutant Rb661W induced a G0/G1 arrest associated with induction of p27KIP1 and repression of cyclin E1 and cyclin E2. Microarray analyses revealed that in addition to down-regulating E2F-responsive genes, Rb repressed expression of Brn-2 (POU3F2), which is implicated as an important transcriptional regulator in retinal progenitor cells and other neuroendocrine cell types. The repression of Brn-2 was a specific Rb effect, as ectopic p27 induced a G0/G1 block, but enhanced, rather than repressed, Brn-2 expression.

CONCLUSION

In addition to Rb effects that occur in many cell types, Rb regulates a gene that selectively governs the behavior of late retinal progenitors and related cells.

A subgroup of microsatellite stable colorectal cancers has elevated mutation rates and different responses to alkylating and oxidising agents

An early step in the carcinogenesis of hereditary non-polyposis colorectal cancer (HNPCC) and some sporadic colorectal cancers (CRCs) is the acquisition of a ‘mutator phenotype’ resulting from defects in DNA mismatch repair (MMR) genes, which normally maintain genomic stability. This mutator phenotype causes an approximately 100–1000-fold increase in base substitutions and small insertion/deletion mutations thereby driving carcinogenesis. It also causes genome-wide microsatellite instability (MSI) due to the inability to repair mutations within these small, hard to replicate, repetitive DNA elements. In contrast, less is known about the role of mutator phenotypes in microsatellite stable (MSS) CRC. In this report, we have measured the mutation rates in 11 MSS CRC cell lines to obtain an estimate of the prevalence of mutator phenotypes in MSS carcinogenesis. Of the 11 cell lines, three of them (27%) possess spontaneous hypoxanthine phosphoribosyltransferase mutation rates approximately 10–100-fold above background. When challenged with alkylating and oxidising agents, the degree of survival and apoptotic responses are different, indicating that these cell lines may represent more than one mutator phenotype. These data demonstrate that a significant portion of MSS CRC cell lines has increased mutation rates and that this may play a role in MSS CRC carcinogenesis.

p107 and p130 Coordinately regulate proliferation, Cbfa1 expression, and hypertrophic differentiation during endochondral bone development

During endochondral bone development, both the chondrogenic differentiation of mesenchyme and the hypertrophic differentiation of chondrocytes coincide with the proliferative arrest of the differentiating cells. However, the mechanisms by which differentiation is coordinated with cell cycle withdrawal, and the importance of this coordination for skeletal development, have not been defined. Through analysis of mice lacking the pRB-related p107 and p130 proteins, we found that p107 was required in prechondrogenic condensations for cell cycle withdrawal and for quantitatively normal alpha1(II) collagen expression. Remarkably, the p107-dependent proliferative arrest of mesenchymal cells was not needed for qualitative changes that are associated with chondrogenic differentiation, including production of Alcian blue-staining matrix and expression of the collagen IIB isoform. In chondrocytes, both p107 and p130 contributed to cell cycle exit, and p107 and p130 loss was accompanied by deregulated proliferation, reduced expression of Cbfa1, and reduced expression of Cbfa1-dependent genes that are associated with hypertrophic differentiation. Moreover, Cbfa1 was detected, and hypertrophic differentiation occurred, only in chondrocytes that had undergone or were undergoing a proliferative arrest. The results suggest that Cbfa1 links a p107- and p130-mediated cell cycle arrest to chondrocyte terminal differentiation.