Phenotypic and proteomic characterization of the human erythroid progenitor continuum reveal dynamic changes in cell cycle and in metabolic pathways

Human erythropoiesis is a complex process leading to the production of 2.5 million red blood cells per second. Following commitment of hematopoietic stem cells to the erythroid lineage, this process can be divided into three distinct stages: erythroid progenitor differentiation, terminal erythropoiesis, and reticulocyte maturation. We recently resolved the heterogeneity of erythroid progenitors into four different subpopulations termed EP1-EP4. Here, we characterized the growth factor(s) responsiveness of these four progenitor populations in terms of proliferation and differentiation. Using mass spectrometry-based proteomics on sorted erythroid progenitors, we quantified the absolute expression of ~5500 proteins from EP1 to EP4. Further functional analyses highlighted dynamic changes in cell cycle in these populations with an acceleration of the cell cycle during erythroid progenitor differentiation. The finding that E2F4 expression was increased from EP1 to EP4 is consistent with the noted changes in cell cycle. Finally, our proteomic data suggest that the protein machinery necessary for both oxidative phosphorylation and glycolysis is present in these progenitor cells. Together, our data provide comprehensive insights into growth factor-dependence of erythroid progenitor proliferation and the proteome of four distinct populations of human erythroid progenitors which will be a useful framework for the study of erythroid disorders.

Insights into highly engraftable hematopoietic cells from 27-year cryopreserved umbilical cord blood

Umbilical cord blood transplantation is a life-saving treatment for malignant and non-malignant hematologic disorders. It remains unclear how long cryopreserved units remain functional, and the length of cryopreservation is often used as a criterion to exclude older units. We demonstrate that long-term cryopreserved cord blood retains similar numbers of hematopoietic stem and progenitor cells compared with fresh and recently cryopreserved cord blood units. Long-term cryopreserved units contain highly functional cells, yielding robust engraftment in mouse transplantation models. We also leverage differences between units to examine gene programs associated with better engraftment. Transcriptomic analyses reveal that gene programs associated with lineage determination and oxidative stress are enriched in high engrafting cord blood, revealing potential molecular markers to be used as potency markers for cord blood unit selection regardless of length of cryopreservation. In summary, cord blood units cryopreserved for extended periods retain engrafting potential and can potentially be used for patient treatment.

Discovery of Highly Potent Small Molecule Pan-Coronavirus Fusion Inhibitors

The unprecedented pandemic of COVID-19, caused by a novel coronavirus, SARS-CoV-2, and its highly transmissible variants, led to massive human suffering, death, and economic devastation worldwide. Recently, antibody-evasive SARS-CoV-2 subvariants, BQ and XBB, have been reported. Therefore, the continued development of novel drugs with pan-coronavirus inhibition is critical to treat and prevent infection of COVID-19 and any new pandemics that may emerge. We report the discovery of several highly potent small-molecule inhibitors. One of which, NBCoV63, showed low nM potency against SARS-CoV-2 (IC₅₀: 55 nM), SARS-CoV-1 (IC₅₀: 59 nM), and MERS-CoV (IC₅₀: 75 nM) in pseudovirus-based assays with excellent selectivity indices (SI > 900), suggesting its pan-coronavirus inhibition. NBCoV63 showed equally effective antiviral potency against SARS-CoV-2 mutant (D614G) and several variants of concerns (VOCs) such as B.1.617.2 (Delta), B.1.1.529/BA.1 and BA.4/BA.5 (Omicron), and K417T/E484K/N501Y (Gamma). NBCoV63 also showed similar efficacy profiles to Remdesivir against authentic SARS-CoV-2 (Hong Kong strain) and two of its variants (Delta and Omicron), SARS-CoV-1, and MERS-CoV by plaque reduction in Calu-3 cells. Additionally, we show that NBCoV63 inhibits virus-mediated cell-to-cell fusion in a dose-dependent manner. Furthermore, the absorption, distribution, metabolism, and excretion (ADME) data of NBCoV63 demonstrated drug-like properties.

Comprehensive phenotyping of erythropoiesis in human bone marrow: Evaluation of normal and ineffective erythropoiesis

Identification of stage-specific erythroid cells is critical for studies of normal and disordered human erythropoiesis. While immunophenotypic strategies have previously been developed to identify cells at each stage of terminal erythroid differentiation, erythroid progenitors are currently defined very broadly. Refined strategies to identify and characterize BFU-E and CFU-E subsets are critically needed. To address this unmet need, a flow cytometry-based technique was developed that combines the established surface markers CD34 and CD36 with CD117, CD71, and CD105. This combination allowed for the separation of erythroid progenitor cells into four discrete populations along a continuum of progressive maturation, with increasing cell size and decreasing nuclear/cytoplasmic ratio, proliferative capacity and stem cell factor responsiveness. This strategy was validated in uncultured, primary erythroid cells isolated from bone marrow of healthy individuals. Functional colony assays of these progenitor populations revealed enrichment of BFU-E only in the earliest population, transitioning to cells yielding BFU-E and CFU-E, then CFU-E only. Utilizing CD34/CD105 and GPA/CD105 profiles, all four progenitor stages and all five stages of terminal erythroid differentiation could be identified. Applying this immunophenotyping strategy to primary bone marrow cells from patients with myelodysplastic syndrome, identified defects in erythroid progenitors and in terminal erythroid differentiation. This novel immunophenotyping technique will be a valuable tool for studies of normal and perturbed human erythropoiesis. It will allow for the discovery of stage-specific molecular and functional insights into normal erythropoiesis as well as for identification and characterization of stage-specific defects in inherited and acquired disorders of erythropoiesis.

Low Seroprevalence of SARS-CoV-2 in Rhode Island blood donors during may 2020 as determined using multiple serological assay formats

BACKGROUND

Epidemic projections and public health policies addressing Coronavirus disease (COVID)-19 have been implemented without data reporting on the seroconversion of the population since scalable antibody testing has only recently become available.

METHODS

We measured the percentage of severe acute respiratory syndrome- Coronavirus-2 (SARS-CoV-2) seropositive individuals from 2008 blood donors drawn in the state of Rhode Island (RI). We utilized multiple antibody testing platforms, including lateral flow immunoassays (LFAs), enzyme-linked immunosorbent assays (ELISAs) and high throughput serological assays (HTSAs). To estimate seroprevalence, we utilized the Bayesian statistical method to adjust for sensitivity and specificity of the commercial tests used.

RESULTS

We report than an estimated seropositive rate of RI blood donors of approximately 0.6% existed in April-May of 2020. Daily new case rates peaked in RI in late April 2020. We found HTSAs and LFAs were positively correlated with ELISA assays to detect antibodies specific to SARS-CoV-2 in blood donors.

CONCLUSIONS

These data imply that seroconversion, and thus infection, is likely not widespread within this population. We conclude that IgG LFAs and HTSAs are suitable to conduct seroprevalence assays in random populations. More studies will be needed using validated serological tests to improve the precision and report the kinetic progression of seroprevalence estimates.

Low Seroprevalence of SARS-CoV-2 in Rhode Island blood donors during may 2020 as determined using multiple serological assay formats

BACKGROUND

Epidemic projections and public health policies addressing Coronavirus disease (COVID)-19 have been implemented without data reporting on the seroconversion of the population since scalable antibody testing has only recently become available.

METHODS

We measured the percentage of severe acute respiratory syndrome- Coronavirus-2 (SARS-CoV-2) seropositive individuals from 2008 blood donors drawn in the state of Rhode Island (RI). We utilized multiple antibody testing platforms, including lateral flow immunoassays (LFAs), enzyme-linked immunosorbent assays (ELISAs) and high throughput serological assays (HTSAs). To estimate seroprevalence, we utilized the Bayesian statistical method to adjust for sensitivity and specificity of the commercial tests used.

RESULTS

We report than an estimated seropositive rate of RI blood donors of approximately 0.6% existed in April-May of 2020. Daily new case rates peaked in RI in late April 2020. We found HTSAs and LFAs were positively correlated with ELISA assays to detect antibodies specific to SARS-CoV-2 in blood donors.

CONCLUSIONS

These data imply that seroconversion, and thus infection, is likely not widespread within this population. We conclude that IgG LFAs and HTSAs are suitable to conduct seroprevalence assays in random populations. More studies will be needed using validated serological tests to improve the precision and report the kinetic progression of seroprevalence estimates.

αI-spectrin represents evolutionary optimization of spectrin for red blood cell deformability

Spectrin tetramers of the membranes of enucleated mammalian erythrocytes play a critical role in red blood cell survival in circulation. One of the spectrins, αI, emerged in mammals with enucleated red cells after duplication of the ancestral α-spectrin gene common to all animals. The neofunctionalized αI-spectrin has moderate affinity for βI-spectrin, whereas αII-spectrin, expressed in nonerythroid cells, retains ancestral characteristics and has a 10-fold higher affinity for βI-spectrin. It has been hypothesized that this adaptation allows for rapid make and break of tetramers to accommodate membrane deformation. We have tested this hypothesis by generating mice with high-affinity spectrin tetramers formed by exchanging the site of tetramer formation in αI-spectrin (segments R0 and R1) for that of αII-spectrin. Erythrocytes with αIIβI presented normal hematologic parameters yet showed increased thermostability, and their membranes were significantly less deformable; under low shear forces, they displayed tumbling behavior rather than tank treading. The membrane skeleton is more stable with αIIβI and shows significantly less remodeling under deformation than red cell membranes of wild-type mice. These data demonstrate that spectrin tetramers undergo remodeling in intact erythrocytes and that this is required for the normal deformability of the erythrocyte membrane. We conclude that αI-spectrin represents evolutionary optimization of tetramer formation: neither higher-affinity tetramers (as shown here) nor lower affinity (as seen in hemolytic disease) can support the membrane properties required for effective tissue oxygenation in circulation.

Seroprevalence of anti-SARS-CoV-2 antibodies in a cohort of New York City metro blood donors using multiple SARS-CoV-2 serological assays: Implications for controlling the epidemic and "Reopening"

Projections of the stage of the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) pandemic and local, regional and national public health policies to limit coronavirus spread as well as "reopen" cities and states, are best informed by serum neutralizing antibody titers measured by reproducible, high throughput, and statically credible antibody (Ab) assays. To date, a myriad of Ab tests, both available and FDA authorized for emergency, has led to confusion rather than insight per se. The present study reports the results of a rapid, point-in-time 1,000-person cohort study using serial blood donors in the New York City metropolitan area (NYC) using multiple serological tests, including enzyme-linked immunosorbent assays (ELISAs) and high throughput serological assays (HTSAs). These were then tested and associated with assays for neutralizing Ab (NAb). Of the 1,000 NYC blood donor samples in late June and early July 2020, 12.1% and 10.9% were seropositive using the Ortho Total Ig and the Abbott IgG HTSA assays, respectively. These serological assays correlated with neutralization activity specific to SARS-CoV-2. The data reported herein suggest that seroconversion in this population occurred in approximately 1 in 8 blood donors from the beginning of the pandemic in NYC (considered March 1, 2020). These findings deviate with an earlier seroprevalence study in NYC showing 13.7% positivity. Collectively however, these data demonstrate that a low number of individuals have serologic evidence of infection during this "first wave" and suggest that the notion of "herd immunity" at rates of ~60% or higher are not near. Furthermore, the data presented herein show that the nature of the Ab-based immunity is not invariably associated with the development of NAb. While the blood donor population may not mimic precisely the NYC population as a whole, rapid assessment of seroprevalence in this cohort and serial reassessment could aid public health decision making.

Escape from neutralizing antibodies by SARS-CoV-2 spike protein variants

Neutralizing antibodies elicited by prior infection or vaccination are likely to be key for future protection of individuals and populations against SARS-CoV-2. Moreover, passively administered antibodies are among the most promising therapeutic and prophylactic anti-SARS-CoV-2 agents. However, the degree to which SARS-CoV-2 will adapt to evade neutralizing antibodies is unclear. Using a recombinant chimeric VSV/SARS-CoV-2 reporter virus, we show that functional SARS-CoV-2 S protein variants with mutations in the receptor-binding domain (RBD) and N-terminal domain that confer resistance to monoclonal antibodies or convalescent plasma can be readily selected. Notably, SARS-CoV-2 S variants that resist commonly elicited neutralizing antibodies are now present at low frequencies in circulating SARS-CoV-2 populations. Finally, the emergence of antibody-resistant SARS-CoV-2 variants that might limit the therapeutic usefulness of monoclonal antibodies can be mitigated by the use of antibody combinations that target distinct neutralizing epitopes.

Selective effects of protein 4.1N deficiency on neuroendocrine and reproductive systems

Protein 4.1N, a member of the protein 4.1 family, is highly expressed in the brain. But its function remains to be fully defined. Using 4.1N^−/− mice, we explored the function of 4.1N in vivo. We show that 4.1N^−/− mice were born at a significantly reduced Mendelian ratio and exhibited high mortality between 3 to 5 weeks of age. Live 4.1N^−/− mice were smaller than 4.1N^+/+ mice. Notably, while there were no significant differences in organ/body weight ratio for most of the organs, the testis/body and ovary/body ratio were dramatically decreased in 4.1N^−/− mice, demonstrating selective effects of 4.1N deficiency on the development of the reproductive systems. Histopathology of the reproductive organs showed atrophy of both testis and ovary. Specifically, in the testis there is a lack of spermatogenesis, lack of leydig cells and lack of mature sperm. Similarly, in the ovary there is a lack of follicular development and lack of corpora lutea formation, as well as lack of secretory changes in the endometrium. Examination of pituitary glands revealed that the secretory granules were significantly decreased in pituitary glands of 4.1N^−/− compared to 4.1N^+/+. Moreover, while GnRH was expressed in both neuronal cell body and axons in the hypothalamus of 4.1N^+/+ mice, it was only expressed in the cell body but not the axons of 4.1N^-/- mice. Our findings uncover a novel role for 4.1N in the axis of hypothalamus-pituitary gland-reproductive system.

Serological Assays Estimate Highly Variable SARS-CoV-2 Neutralizing Antibody Activity in Recovered COVID19 Patients

The development of neutralizing antibodies (nAb) against SARS-CoV-2, following infection or vaccination, is likely to be critical for the development of sufficient population immunity to drive cessation of the COVID19 pandemic. A large number of serologic tests, platforms and methodologies are being employed to determine seroprevalence in populations to select convalescent plasmas for therapeutic trials, and to guide policies about reopening. However, tests have substantial variability in sensitivity and specificity, and their ability to quantitatively predict levels of nAb is unknown. We collected 370 unique donors enrolled in the New York Blood Center Convalescent Plasma Program between April and May of 2020. We measured levels of antibodies in convalescent plasma using commercially available SARS-CoV- 2 detection tests and in-house ELISA assays and correlated serological measurements with nAb activity measured using pseudotyped virus particles, which offer the most informative assessment of antiviral activity of patient sera against viral infection. Our data show that a large proportion of convalescent plasma samples have modest antibody levels and that commercially available tests have varying degrees of accuracy in predicting nAb activity. We found the Ortho Anti-SARS-CoV-2 Total Ig and IgG high throughput serological assays (HTSAs), as well as the Abbott SARS-CoV-2 IgG assay, quantify levels of antibodies that strongly correlate with nAb assays and are consistent with gold-standard ELISA assay results. These findings provide immediate clinical relevance to serology results that can be equated to nAb activity and could serve as a valuable ‘roadmap’ to guide the choice and interpretation of serological tests for SARS-CoV-2.

COVID19 antibody detection using lateral flow assay tests in a cohort of convalescent plasma donors

Objective

COVID19 has caused a global and ongoing pandemic. The need for population seroconversion data is apparent to monitor and respond to the pandemic. Using a lateral flow assay (LFA) testing platform, the seropositivity in 63 New York Blood Center (NYBC) Convelescent Plasma (CP) donor samples were evaluated for the presence of COVID19 specific IgG and IgM.

Results

CP donors showed diverse antibody result. Convalescent donor plasma contains SARS-CoV-2 specific antibodies. Weak antibody bands may identify low titer CP donors. LFA tests can identify antibody positive individuals that have recovered from COVID19. Confirming suspected cases using antibody detection could help inform the patient and the community as to the relative risk to future exposure and a better understanding of disease exposure.

Escape from neutralizing antibodies by SARS-CoV-2 spike protein variants

Neutralizing antibodies elicited by prior infection or vaccination are likely to be key for future protection of individuals and populations against SARS-CoV-2. Moreover, passively administered antibodies are among the most promising therapeutic and prophylactic anti-SARS-CoV-2 agents. However, the degree to which SARS-CoV-2 will adapt to evade neutralizing antibodies is unclear. Using a recombinant chimeric VSV/SARS-CoV-2 reporter virus, we show that functional SARS-CoV-2 S protein variants with mutations in the receptor binding domain (RBD) and N-terminal domain that confer resistance to monoclonal antibodies or convalescent plasma can be readily selected. Notably, SARS-CoV-2 S variants that resist commonly elicited neutralizing antibodies are now present at low frequencies in circulating SARS-CoV-2 populations. Finally, the emergence of antibody-resistant SARS-CoV-2 variants that might limit the therapeutic usefulness of monoclonal antibodies can be mitigated by the use of antibody combinations that target distinct neutralizing epitopes.

How did we rapidly implement a convalescent plasma program?

Since the beginning of the COVID-19 pandemic, the use of convalescent plasma as a possible treatment has been explored. Here we describe our experience as the first U.S. organization creating a COVID-19 convalescent plasma program to support its use through the single-patient emergency investigational new drug, the National Expanded Access Program, and multiple randomized controlled trials. Within weeks, we were able to distribute more than 8000 products, scale up collections to more than 4000 units per week, meet hospital demand, and support randomized controlled trials to evaluate the efficacy of convalescent plasma treatment. This was through strategic planning; redeployment of staff; and active engagement of hospital, community, and public health partners. Our partners helped with donor recruitment, testing, patient advocacy, and patient availability. The program will continue to evolve as we learn more about optimizing the product. Remaining issues to be resolved are antibody titers, dose, and at what stage of disease to transfuse.

Ten years of TRALI mitigation: measuring our progress

BACKGROUND

Transfusion-related acute lung injury (TRALI) is a leading cause of transfusion-associated mortality for which multiple mitigation strategies have been implemented over the past decade. However, product-specific TRALI rates have not been reported longitudinally and may help refine additional mitigation strategies.

STUDY DESIGN AND METHODS

This retrospective multicenter study included analysis of TRALI rates from 2007 through 2017. Numerators included definite or probable TRALI reports from five blood centers serving nine states in the United States. Denominators were components distributed from participating centers. Rates were calculated as per 100,000 components distributed (p < 0.05 significant).

RESULTS

One hundred four TRALI cases were reported from 10,012,707 components distributed (TRALI rate of 1.04 per 100,000 components). The TRALI rate was 2.25 for female versus 1.08 for male donated components (p < .001). The TRALI rate declined from 2.88 in 2007 to 0.60 in 2017. From 2007 to 2013, there was a significantly higher TRALI rate associated with female versus male plasma (33.85 vs. 1.59; p < 0.001) and RBCs (1.97 vs. 1.15; p = 0.03). From 2014 through 2017, after implementation of mitigation strategies, a significantly higher TRALI rate only from female-donated plateletpheresis continued to be observed (2.98 vs. 0.75; p = 0.04).

CONCLUSION

Although the TRALI rates have substantially decreased secondary to multiple strategies over the past decade, a residual risk remains, particularly with female-donated plateletpheresis products. Additional tools that may further mitigate TRALI incidence include the use of buffy coat pooled platelets suspended in male donor plasma or platelet additive solution due to the lower amounts of residual plasma.

Deubiquitylase USP7 regulates human terminal erythroid differentiation by stabilizing GATA1

Ubiquitination is an enzymatic post-translational modification that affects protein fate. The ubiquitin-proteasome system (UPS) was first discovered in reticulocytes where it plays important roles in reticulocyte maturation. Recent studies have revealed that ubiquitination is a dynamic and reversible process and that deubiquitylases are capable of removing ubiquitin from their protein substrates. Given the fact that the UPS is highly active in reticulocytes, it is speculated that deubiquitylases may play important roles in erythropoiesis. Yet, the role of deubiquitylases in erythropoiesis remains largely unexplored. In the present study, we found that the expression of deubiquitylase USP7 is significantly increased during human terminal erythroid differentiation. We further showed that interfering with USP7 function, either by short hairpin RNA-mediated knockdown or USP7-specific inhibitors, impaired human terminal erythroid differentiation due to decreased GATA1 level and that restoration of GATA1 levels rescued the differentiation defect. Mechanistically, USP7 deficiency led to a decreased GATA1 protein level that could be reversed by proteasome inhibitors. Furthermore, USP7 interacts directly with GATA1 and catalyzes the removal of K48-linked poly ubiquitylation chains conjugated onto GATA1, thereby stabilizing GATA1 protein. Collectively, our findings have identified an important role of a deubiquitylase in human terminal erythroid differentiation by stabilizing GATA1, the master regulator of erythropoiesis.

TET2 deficiency leads to stem cell factor-dependent clonal expansion of dysfunctional erythroid progenitors

Myelodysplastic syndromes (MDSs) are clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis. Anemia is the defining cytopenia of MDS patients, yet the molecular mechanisms for dyserythropoiesis in MDSs remain to be fully defined. Recent studies have revealed that heterozygous loss-of-function mutation of DNA dioxygenase TET2 is 1 of the most common mutations in MDSs and that TET2 deficiency disturbs erythroid differentiation. However, mechanistic insights into the role of TET2 on disordered erythropoiesis are not fully defined. Here, we show that TET2 deficiency leads initially to stem cell factor (SCF)-dependent hyperproliferation and impaired differentiation of human colony-forming unit-erythroid (CFU-E) cells, which were reversed by a c-Kit inhibitor. We further show that this was due to increased phosphorylation of c-Kit accompanied by decreased expression of phosphatase SHP-1, a negative regulator of c-Kit. At later stages, TET2 deficiency led to an accumulation of a progenitor population, which expressed surface markers characteristic of normal CFU-E cells but were functionally different. In contrast to normal CFU-E cells that require only erythropoietin (EPO) for proliferation, these abnormal progenitors required SCF and EPO and exhibited impaired differentiation. We termed this population of progenitors "marker CFU-E" cells. We further show that AXL expression was increased in marker CFU-E cells and that the increased AXL expression led to increased activation of AKT and ERK. Moreover, the altered proliferation and differentiation of marker CFU-E cells were partially rescued by an AXL inhibitor. Our findings document an important role for TET2 in erythropoiesis and have uncovered previously unknown mechanisms by which deficiency of TET2 contributes to ineffective erythropoiesis.

Donor incentives improve cardiovascular disease risk profile and donation rates

BACKGROUND

Blood centers may offer point-based reward systems or cardiovascular disease (CVD) screening to incentivize donors. However, combining these incentives to improve CVD risk and blood donation rates has not been studied.

STUDY DESIGN AND METHODS

Study was a three-arm prospective controlled trial: Group 1, control (routine points, no CVD screening); Group 2, CVD screening with routine points; and Group 3, CVD screening plus incentive double points. The primary objective was to determine if double versus routine incentive points led to improvement or maintenance of CVD risk profile assessed using self-reported changes in 1) reading food labels for calorie and fat content, 2) exercising daily, 3) reduced fat intake, and 4) increase in eating fruits and vegetables. Outcomes were compared at first and final (2-year) follow-up visits. As secondary outcome, median blood donation rates before enrollment and during study were compared.

RESULTS

A total of 570 donors (290 in Group 1, 134 in Group 2, 146 Group 3) were selected. At first follow-up visit, 71.4% in Group 3 versus 62.0% in Group 2 subjects reported at least one of four positive behavioral changes (p < 0.001). Increase in reading food labels for calorie and fat content was the most common change and higher in Group 3 (Group 3 from 60.9% to 79.1%; Group 2 from 67.6% to 77.5%; p < 0.001). Final evaluation showed significant increase in self-reported exercise in Group 3 only (from baseline 52.9% to 68.3%; p < 0.05). Group 3 reported higher increase in median number of donations/year during study enrollment (6.8 [IQR, 4.3-12] vs. baseline 4.6 [IQR, 3.2-7.1] donations/year) than Group 2 (5.6 [IQR, 4.2-10.5] vs. baseline 4.9 [IQR, 3.5-10.2]) and Group 1 (4.4 [IQR, 2.7-8.0] vs. baseline 4.4 [IQR, 2.5-6.0] donations/year; p < 0.001).

CONCLUSION

Positive donor reinforcement (double vs. routine points) resulted in better self-reported health maintenance behavior and increased donation rates.

SF3B1 deficiency impairs human erythropoiesis via activation of p53 pathway: implications for understanding of ineffective erythropoiesis in MDS

BACKGROUND

SF3B1 is a core component of splicing machinery. Mutations in SF3B1 are frequently found in myelodysplastic syndromes (MDS), particularly in patients with refractory anemia with ringed sideroblasts (RARS), characterized by isolated anemia. SF3B1 mutations have been implicated in the pathophysiology of RARS; however, the physiological function of SF3B1 in erythropoiesis remains unknown.

METHODS

shRNA-mediated approach was used to knockdown SF3B1 in human CD34+ cells. The effects of SF3B1 knockdown on human erythroid cell differentiation, cell cycle, and apoptosis were assessed by flow cytometry. RNA-seq, qRT-PCR, and western blot analyses were used to define the mechanisms of phenotypes following knockdown of SF3B1.

RESULTS

We document that SF3B1 knockdown in human CD34+ cells leads to increased apoptosis and cell cycle arrest of early-stage erythroid cells and generation of abnormally nucleated late-stage erythroblasts. RNA-seq analysis of SF3B1-knockdown erythroid progenitor CFU-E cells revealed altered splicing of an E3 ligase Makorin Ring Finger Protein 1 (MKRN1) and subsequent activation of p53 pathway. Importantly, ectopic expression of MKRN1 rescued SF3B1-knockdown-induced alterations. Decreased expression of genes involved in mitosis/cytokinesis pathway including polo-like kinase 1 (PLK1) was noted in SF3B1-knockdown polychromatic and orthochromatic erythroblasts comparing to control cells. Pharmacologic inhibition of PLK1 also led to generation of abnormally nucleated erythroblasts.

CONCLUSIONS

These findings enabled us to identify novel roles for SF3B1 in human erythropoiesis and provided new insights into its role in regulating normal erythropoiesis. Furthermore, these findings have implications for improved understanding of ineffective erythropoiesis in MDS patients with SF3B1 mutations.

Immune Regulation of sickle Cell Alloimmunization

Red blood cell (RBC) transfusion remains an important treatment for patients with sickle cell disease (SCD) and the majority of patients receive transfusions by adulthood. However, SCD patients are at a high risk of alloimmunization, which can cause life-threatening complications. The high rate of alloimmunization can in part be explained by chronic inflammatory condition in SCD characterized by significant immune and inflammatory activation. Heightened immune effector cell responses and/or impaired regulatory networks are likely to drive alloantibody production in alloimmunized SCD patients. In support of this, altered T cell immunoregulation, known to control antibody responses, have been reported in alloimmunized SCD patients. In addition, stronger follicular help T cell responses that help antibody production by B cells were described in alloimmunized as compared to non-alloimmunized SCD patients. Furthermore, several innate immune abnormalities have been identified in alloimmunized SCD patients, including a compromised anti-inflammatory response against extracellular cell free heme. The data support a model in which alloimmunized SCD patients are unable to switch off their proinflammatory state in response to the ongoing hemolytic state characteristic of SCD, placing this patient subset at a higher risk to develop a strong immune response against allogeneic determinants on transfused RBCs, thus increasing the risk of further alloimmunization. A detailed mechanistic understanding of innate immune abnormalities that can contribute to pathogenic T cell responses in alloimmunized SCD patients will lay the foundation for identification of biomarkers of alloimmunization with the goal that this information will ultimately help guide therapy in these patients.

Storage characteristics of multiple-donor pooled red blood cells compared to single-donor red blood cell units

BACKGROUND

Each unit of blood donated is processed and stored individually resulting in variability in the amount of red blood cells (RBCs) collected, RBC properties, and the 24-hour posttransfusion RBC survivability. As a result, each unit differs in its ability to deliver oxygen and potentially its effects on the recipient. The goal of this study was to investigate the storage of pooled RBCs from multiple donors in comparison to control standard RBC units.

STUDY DESIGN AND METHODS

Two units of irradiated, leukoreduced RBCs of same ABO, D, E, C, and K antigen phenotype were collected from each of five donors using apheresis. One unit from each donor was pooled in a 2-L bag and remaining units were used as controls. After being pooled, RBCs were separated in five bags and stored at 4°C along with the controls. Quality indexes were measured on Days 2, 14, and 28 for all the units.

RESULTS

Adenosine triphosphate assays for both pooled and controls showed a slight decrease from Day 2 to Day 28 (pooled/control from 5.22/5.24 to 4.35/4.33 µmol/g hemoglobin [Hb]). 2,3-Diphosphoglycerate was successfully rejuvenated for all RBC units on Day 28 (pooled 11.46 µmol/g Hb; control 11.86 µmol/g Hb). The results showed a nonsignificant difference between pooled and control units, with a general trend of lower standard deviation for pooled units when compared to controls.

CONCLUSION

Pooled units have reduced unit-to-unit variability. Future exploration of their immunogenicity is required before using pooled units for transfusion.

Blood transfusion and breast milk transmission of cytomegalovirus in very low-birth-weight infants: a prospective cohort study

IMPORTANCE

Postnatal cytomegalovirus (CMV) infection can cause serious morbidity and mortality in very low-birth-weight (VLBW) infants. The primary sources of postnatal CMV infection in this population are breast milk and blood transfusion. The current risks attributable to these vectors, as well as the efficacy of approaches to prevent CMV transmission, are poorly characterized.

OBJECTIVE

To estimate the risk of postnatal CMV transmission from 2 sources: (1) transfusion of CMV-seronegative and leukoreduced blood and (2) maternal breast milk.

DESIGN, SETTING, AND PARTICIPANTS

A prospective, multicenter birth-cohort study was conducted from January 2010 to June 2013 at 3 neonatal intensive care units (2 academically affiliated and 1 private) in Atlanta, Georgia. Cytomegalovirus serologic testing of enrolled mothers was performed to determine their status. Cytomegalovirus nucleic acid testing (NAT) of transfused blood components and breast milk was performed to identify sources of CMV transmission. A total of 539 VLBW infants (birth weight, ≤ 1500 g) who had not received a blood transfusion were enrolled, with their mothers (n = 462), within 5 days of birth. The infants underwent serum and urine CMV NAT at birth to evaluate congenital infection and surveillance CMV NAT at 5 additional intervals between birth and 90 days, discharge, or death.

EXPOSURES

Blood transfusion and breast milk feeding.

MAIN OUTCOMES AND MEASURES

Cumulative incidence of postnatal CMV infection, detected by serum or urine NAT.

RESULTS

The seroprevalence of CMV among the 462 enrolled mothers was 76.2% (n = 352). Among the 539 VLBW infants, the cumulative incidence of postnatal CMV infection at 12 weeks was 6.9% (95% CI, 4.2%-9.2%); 5 of 29 infants (17.2%) with postnatal CMV infection developed symptomatic disease or died. A total of 2061 transfusions were administered among 57.5% (n = 310) of the infants; none of the CMV infections was linked to transfusion, resulting in a CMV infection incidence of 0.0% (95% CI, 0.0%-0.3%) per unit of CMV-seronegative and leukoreduced blood. Twenty-seven of 28 postnatal infections occurred among infants fed CMV-positive breast milk (12-week incidence, 15.3%; 95% CI, 9.3%-20.2%).

CONCLUSIONS AND RELEVANCE

Transfusion of CMV-seronegative and leukoreduced blood products effectively prevents transmission of CMV to VLBW infants. Among infants whose care is managed with this transfusion approach, maternal breast milk is the primary source of postnatal CMV infection.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00907686.

The value of area-based analyses of donation patterns for recruitment strategies

BACKGROUND

Lack of ready access to a donation site may be a potential barrier to or influence the frequency of blood donations. In this study, we applied geographic analysis to blood donor behavior and use of different donation sites.

STUDY DESIGN AND METHODS

The study population consisted of blood donors who gave whole blood in Georgia between 2004 and 2008. Zip code, city, and county of donor's residence were matched with the addresses of their donation sites. Donors were dichotomized as either nonmetro Atlanta or metro Atlanta residents. Six donation site categories were defined: donation within the same or a different zip code, within the same or a different city, and within the same or a different county. Logistic regression was used to compare donations by zip code, city, and county.

RESULTS

The study population consisted of 402,692 blood donors who donated 1,147,442 whole blood units between 2004 and 2008, more than half of whom (56.4%) resided in the metro Atlanta area. The majority of donors were white (75.0%) and female (55.7%). In nonmetro Atlanta, repeat donors were more likely to have donated at fixed sites (p < 0.001). In metro Atlanta, repeat donors were more likely to have donated at a mobile site than at a fixed site (p < 0.001).

CONCLUSION

Geographic and demographic differences in blood donation patterns exist. The locations of donor residences and blood donation sites influence donor behaviors. Understanding the geographic influence on donation patterns provides an important tool for optimizing donor recruitment strategies.

Early trauma induced coagulopathy (ETIC): prevalence across the injury spectrum

INTRODUCTION

Newer studies have hypothesised about a coagulopathy that occurs early after trauma, early trauma induced coagulopathy, ETIC, and is defined by an elevated admission prothrombin time (PT). Also, referred to by some authors as acute traumatic coagulopathy, it has been most often studied in cohorts of severely injured or hypotensive patients. However, we wanted to prospectively investigate ETIC in a large all-comers cohort to confirm its prevalence across the entire spectrum of injury, to evaluate its risk pattern and to determine a possible relationship to reduced survival.

METHODS

We conducted a prospective cohort study at a Level I trauma centre from July 15, 2008 to November 15, 2009. Demographics, injury mechanism, time from injury and to hospital arrival, fluid and blood administration and vital signs were collected at hospital arrival and to the time of first blood sample collection for all patients admitted for 24h or longer. Our primary outcome was the incidence of mortality by the 28th hospital day, referred to as 28 day in-hospital mortality.

RESULTS

701 patients were included in the final study cohort. There was 75.3% male, 25.7% penetrating, with a mean age of 39 years. The overall mortality was 7.3%. ETIC occurred in 114 patients (16.3%) and was found to be independently associated with death (odds of death (per 0.10s increase in PT): 1.10, p=0.001). ETIC patients, as a group, were more severely injured, had more hypotension and head injury and used more crystalloid and blood products than non-ETIC patients. However, even mildly injured patients, who had an ISS<16, normal RTS score, and no fluid resuscitation, had an ETIC prevalence of 11.7% (11/94).

CONCLUSIONS

ETIC is an early, primary post-injury coagulopathy that occurs in 16.3% of admitted trauma patients. It is associated with an increase in mortality, even when controlling for crystalloids, vital signs, injury severity and head injury. It can also be found in approximately 11% of mildly injured patients (patients without physiological derangement or blood product administration). Therefore, further elucidation of ETIC is strategic to impacting trauma patient outcome.

The integration of high-throughput testing of blood donors for cardiovascular disease risk assessment and prevention

BACKGROUND AND OBJECTIVES

Some blood centers provide health screening as a public health measure and to encourage donation. The goal of the current study was to provide cardiovascular disease (CVD) screening to donors using high-throughput testing and web-based communications.

MATERIALS AND METHODS

CVD risk screening was offered to donors at selected mobile drives in a large metropolitan area. Risk factors were determined by donor questionnaire, laboratory testing (total cholesterol, HDL levels and hemoglobin A1c), and blood pressure measurement. Results were reported to participants via mail and website. A 60-day follow up web-based survey was sent to participants via email to assess the impact of the program on donor's behavior.

RESULTS

9435 donors, 17-75 years old participated with the following risk factors: 61.3% BMIs>25, 28.8% high total cholesterol, and 31.4% lower than recommended HDL levels. 25.3% of donors that responded to the follow up survey went to see their health care provider based on screening results and 9% of these received new or modified treatment.

CONCLUSION

In our sample, blood donors are healthier than the general population, but many still have CVD risk factors, particularly obesity. CVD screening can be successfully used to make donors aware of this important health information and some donors act on this information.

Evaluating the role of blood collection centers in public health: a status report

Blood centers have a central role in the community through recruitment and donation, and these community interactions enable blood centers to have a critical role in public health. Some public health initiatives are inherent in the blood center, such as providing human immunodeficiency virus educational material, whereas other initiatives have been actively created, such as cardiovascular screening, as a means to increase blood donor rates and increase the blood center's community interaction. These public health initiatives have been inconsistently practiced by blood collection centers over many years. An understanding of the current literature and exploring the potential role of blood centers in public health, while considering cost and value of these programs, are necessary for blood centers to evaluate the value of implementing these programs. The studies do not support a significant improvement in donor health or significant increase in donation rates through these public health initiatives. However, no study published thus far has been comprehensive enough or carried out long enough to adequately evaluate the value of providing health initiatives to donors.

Pathophysiology of early trauma-induced coagulopathy: emerging evidence for hemodilution and coagulation factor depletion

BACKGROUND

Trauma patients present with a coagulopathy, termed early trauma-induced coagulopathy (ETIC), that is associated with increased mortality. This study investigated hemostatic changes responsible for ETIC.

METHODS

Case-control study of trauma patients with and without ETIC, defined as prolonged prothrombin time (PT), was performed from prospective cohort of consecutive trauma patients who presented to Level I trauma center. Univariate and multivariate analyses were performed.

RESULTS

The case-control study group (n = 91) was 80% male, with mean age of 37 years, 17% penetrating trauma and 7% mortality rate. Patients with ETIC demonstrated decreased common and extrinsic pathway factor activities (factors V and VII) and decreased inhibition of the coagulation cascade (antithrombin and protein C activities) when compared with the matched control patients without ETIC. Both cohorts had evidence of increased thrombin and fibrin generation (prothrombin fragment 1.2 levels, thrombin-antithrombin complexes, and soluble fibrin monomer), increased fibrinolysis (d-dimer levels), and increased inhibition of fibrinolysis (plasminogen activator inhibitor-1 activity) above normal reference values. Patients with versus without ETIC had increased mortality and received increased amount of blood products.

CONCLUSION

ETIC following injury is associated with decreased factor activities without significant differences in thrombin and fibrin generation, suggesting that despite these perturbations in the coagulation cascade, patients displayed a balanced hemostatic response to injury. The lower factor activities are likely secondary to increased hemodilution and coagulation factor depletion. Thus, decreasing the amount of crystalloid infused in the early phases following trauma and administration of coagulation factors may prevent the development.

A novel mouse model of red blood cell storage and posttransfusion in vivo survival

BACKGROUND

Storage of red blood cells (RBCs) is necessary for an adequate blood supply. However, reports have identified potential negative sequelae of transfusing stored RBCs. An animal model would be useful to investigate the pathophysiology of transfusing stored RBCs. However, it has been reported that storage of rat RBCs in CPDA-1 resulted in an unexpected sudden decline in posttransfusion survival. A mouse model of RBC storage and transfusion was developed to assess survival kinetics of mouse RBCs.

STUDY DESIGN AND METHODS

RBCs expressing green fluorescent protein were collected in CPDA-1, filter leukoreduced, adjusted to a 75% hematocrit, and stored at 4°C. At weekly intervals, stored RBCs were transfused into C57BL/6 recipients. RBC survival was measured by flow cytometry and chromium-51 labeling. Phosphatidylserine externalization and CD47 expression was also evaluated.

RESULTS

Mean 24-hour survivals of transfused RBCs were 99, 91, 64, 54, 30, and 18% after 0, 7, 14, 21, 28, and 35 days of storage, respectively. Stored RBCs showed an initial rapid clearance with subsequent extended survival. Increased surface phosphatidylserine and decreased CD47 expression were also observed.

CONCLUSIONS

Mouse RBCs showed a progressive decline in survival, as a function of storage time, unlike the precipitous loss of viability reported for rat RBCs. Moreover, changes in the measured surface markers were analogous to trends reported for human RBCs. Together, these findings provide an initial characterization of a novel mouse model of RBC storage with the potential to serve as an experimental platform for studying the pathophysiologic consequences of transfusing stored RBCs.

The spleen plays a central role in primary humoral alloimmunization to transfused mHEL red blood cells

BACKGROUND

Several differences exist between antigens on transfused red blood cells (RBCs) and other immunogens, including anatomical compartmentalization. Whereas antigens from microbial pathogens and solid organ transplants drain into local lymph nodes, circulating RBCs remain segregated in the peripheral circulation, where they are consumed by antigen-presenting cells (APCs) in the spleen and liver. Accordingly, it was hypothesized that the splenic APCs play a central role in primary alloimmunization to transfused RBCs.

STUDY DESIGN AND METHODS

Recipient mice were splenectomized and transfused with transgenic RBCs expressing the membrane-bound hen egg lysozyme (mHEL) model RBC antigen. In some experiments, mHEL-specific CD4+ T cells were adoptively transferred into recipient mice to allow investigation of helper T-cell responses. Unmanipulated or sham-splenectomized mice served as controls. Recombinant murine cytomegalovirus expressing mHEL (mHEL-MCMV) was used as a control non-RBC immunogen. Humoral responses were measured by mHEL-specific enzyme-linked immunosorbent assay and flow cytometric–based RBC cross-match.

RESULTS

Control animals synthesized detectable anti-HEL immunoglobulin (Ig)G after a single mHEL RBC transfusion. mHEL-specific CD4+ T cells underwent robust expansion, and adoptive transfer of CD4+ T cells resulted in a 1000-fold increase in anti-HEL IgG. In contrast, minimal anti-HEL IgG was detectable in splenectomized mice, mHEL-specific CD4+ T cells did not proliferate, and adoptive transfer did not increase anti-HEL IgG. However, anti-HEL IgG response after exposure to mHEL-MCMV was equivalent in control and splenectomized mice.

DISCUSSION

Together, these findings illustrate the distinct properties of transfused RBCs as immunologic stimuli, with the spleen playing a critical role in primary RBC alloimmunization at the level of CD4+ T-cell activation.

Prevention of transfusion-transmitted cytomegalovirus in low-birth weight infants (≤1500 g) using cytomegalovirus-seronegative and leukoreduced transfusions

The transfusion-transmitted cytomegalovirus (TT-CMV) can cause serious morbidity and mortality in low-birth weight infants (LBWIs). Transfusion-transmitted cytomegalovirus can be minimized in LBWIs born to cytomegalovirus (CMV)-seronegative mothers with the use of CMV-seronegative blood components. Despite evidence that has independently shown that either leukoreduction or the use of CMV-seronegative components mitigates TT-CMV, the potential efficacy of combining these 2 strategies has not been substantiated in very LBWIs (<1500 g) born to either CMV-seronegative or CMV-seropositive mothers. Nonetheless, the serious risks of CMV infection posed by allogeneic transfusions and the broad implementation of universal leukoreduction have made this combination strategy the de facto clinical standard for transfusion of LBWIs. Although preferred, this combined approach has not been validated in clinical trials and, thus, warrants a large prospective study to determine whether this is the optimal transfusion tactic or if additional safety measures are necessary to prevent TT-CMV in LBWIs born to both CMV- seronegative and CMV-seropositive mothers. The aim of this prospective birth cohort study, therefore, is to estimate the incidence of TT-CMV in 1300 LBWIs (≤1500 g) who receive CMV-seronegative plus leuko-reduced blood products to evaluate the effectiveness of this coupled strategy. Conducted in Atlanta, GA, this study has been registered at the US National Institutes of Health (ClinicalTrials.gov no. NCT00907686).

Receiver operating characteristic curve analysis of circulating blood dendritic cell precursors and T cells predicts response to extracorporeal photopheresis in patients with chronic graft-versus-host disease

BACKGROUND

One proposed mechanism of extracorporeal photopheresis (ECP) in reducing chronic graft-versus-host disease (cGVHD) is alteration in numbers of circulating dendritic cells (DCs). This hypothesis was tested by correlating numbers of DC precursors and T cells in the blood before and during ECP therapy with response of cGVHD.

STUDY DESIGN AND METHODS

Twenty-five patients with cGVHD were treated with ECP. Data were collected with emphasis on blood cellular markers, clinical response to ECP, and overall survival.

RESULTS

Fourteen patients (56%) responded and had better 2-year survival than nonresponders (88% vs. 18%, p=0.003). Responders had higher baseline circulating myeloid DC (mDC) and plasmacytoid DC precursors and CD4+ and CD8+ T cells compared with nonresponders. Receiver operating characteristic curve analyses showed that the best baseline cutoff values to predict response to ECP were mDC counts of 3.7 cells/µL (79% sensitivity, 82% specificity) and CD4+ T-cell counts of 104 cells/µL (71% sensitivity, 82% specificity). CD4+ T cells declined in responders over time, but not in nonresponders, and no significant changes were seen in CD8 T-cell or DC numbers over a 12-month period in responder or nonresponder groups.

CONCLUSIONS

Higher baseline numbers of circulating DCs and T cells may predict clinical response to ECP in patients with cGVHD.

Do red cell transfusions increase the risk of necrotizing enterocolitis in premature infants?

OBJECTIVE

To test the hypothesis that red blood cell (RBC) transfusions increase the risk of necrotizing enterocolitis (NEC) in premature infants, we investigated whether the risk of "transfusion-associated" NEC is higher in infants with lower hematocrits and advanced postnatal age.

STUDY DESIGN

Retrospective comparison of NEC patients and control patients born at < 34 weeks gestation.

RESULTS

The frequency of RBC transfusions was similar in NEC patients (47/93, 51%) and control patients (52/91, 58%). Late-onset NEC (> 4 weeks of age) was more frequently associated with a history of transfusion(s) than early-onset NEC (adjusted OR, 6.7; 95% CI, 1.5 to 31.2; P = .02). Compared with nontransfused patients, RBC-transfused patients were born at earlier gestational ages, had greater intensive care needs (including at the time of onset of NEC), and longer hospital stay. A history of RBC transfusions within 48-hours before NEC onset was noted in 38% of patients, most of whom were extremely low birth weight infants.

CONCLUSIONS

In most patients, RBC transfusions were temporally unrelated to NEC and may be merely a marker of overall severity of illness. However, the relationship between RBC transfusions and NEC requires further evaluation in extremely low birth weight infants using a prospective cohort design.

Minority donation in the United States: challenges and needs

PURPOSE OF REVIEW

In the United States, blood donation rates of African-Americans are 25-50% of that of white individuals. As African-Americans make up an ever increasing and now substantial minority, and African-American recipients of blood transfusion, both specialized, such as sickle cell disease patients, and general hospitalized patients, have a better chance of receiving phenotype-matched or appropriate red blood cell units when there is a significant percentage of products in the inventory from African-American donors, it is important to understand the reason for the observed difference.

RECENT FINDINGS

Possible reasons for this discrepancy in donation rates include increased rates of donor deferral and ineligibility; increased barriers to donation, such as fear and distrust; and different marketing and education strategies. Thus, to increase the blood availability to African-American recipients, the reasons for these donation rate differences must be better understood and subsequently addressed through improved blood donor recruitment programs. The majority of African-American donor recruitment programs have focused on donating for sickle cell disease patients, particularly children, which have been of limited success.

SUMMARY

Significant improvements in African-American donor recruitment are needed to adequately meet the demand of African-American patients as well as the entire population.

Effects of storage duration and volume on the quality of leukoreduced apheresis-derived platelets: implications for pediatric transfusion medicine

BACKGROUND

Platelet (PLT) storage adversely affects PLT structure and function in vitro and is associated with decreased PLT recovery and function in vivo. In pediatric transfusion medicine, it is not uncommon for small residual volumes to remain in parent units after aliquot preparation of leukoreduced apheresis-derived PLTs (LR-ADP). However, limited data exist regarding the impact of storage on residual small-volume LR-ADP.

STUDY DESIGN AND METHODS

Standard metabolic testing was performed on residual volumes of LR-ADP after aliquot removal and PLT aggregometry using a dual agonist of ADP and collagen was performed on stored, small-volume aliquots (10-80mL) created from an in vitro model of PLT storage.

RESULTS

Seventy-seven LR-ADP underwent metabolic (n=67) or metabolic and aggregation (n=10) studies. All products maintained a pH value of more than 6.89 throughout storage. Lactate and pCO(2) increased proportionally with longer storage time. Regardless of acceptable metabolism during storage, aggregation in 10- to 20-mL aliquots was impaired by Day 4 and aliquots less than 40 mL demonstrated the most dramatic decrease in aggregation from baseline.

CONCLUSIONS

Despite maintenance of acceptable metabolic conditions, residual volumes of LR-ADP develop impaired aggregation in vitro that may adversely affect PLT survival and function in vivo. At volumes below 40mL, LR-ADP revealed reduced aggregation. As a result, it is recommended to monitor and record volumes of LR-ADP used for pediatric transfusion. Moreover, once LR-ADP attain a volume of 50mL or less on Day 4 or Day 5 of storage, consider discarding these products until their in vivo efficacy can be studied.

Hepatitis C virus prevalence and clearance among US blood donors, 2006-2007: associations with birth cohort, multiple pregnancies, and body mass index

BACKGROUND

During the period 1992-1993, the prevalence of hepatitis C virus (HCV) antibodies (anti-HCV) among US blood donors was 0.36%, but contemporary data on the prevalence of antibody to HCV and the prevalence of HCV RNA are lacking.

METHODS

We performed a large, cross-sectional study of blood donors at 6 US blood centers during 2006-2007. Anti-HCV was measured with enzyme-linked immunosorbent assay followed by immunoblot, and HCV RNA was measured with nucleic acid testing. Adjusted odds ratios (aORs) were derived using multivariable logistic regression.

RESULTS

Of 959,281 donors, 695 had anti-HCV detected (prevalence, 0.072%). Of those with anti-HCV, 516 (74%) had test results positive for HCV RNA, and 179 (26%) had test results that were negative for HCV RNA. Compared with the prevalence during the period 1992-1993, prevalence during 2006-2007 was lower and peaked in older age groups. Anti-HCV was associated with a body mass index (BMI) >30 (aOR, 0.6; 95% confidence interval [CI], 0.5-0.8), and among women, it was associated with higher gravidity (aOR for 5 vs 0 pregnancies, 3.2; 95% CI, 1.9-5.4). HCV RNA negative status was associated with black race (aOR, 0.4; 95% CI, 0.2-0.7), having more than a high school education (aOR, 1.6; 95% CI, 1.1-2.4), and BMI >30 (aOR, 2.4; 95% CI, 1.4-3.9).

CONCLUSIONS

Decreasing HCV prevalence is most likely attributable to culling of seropositive donors and a birth cohort effect. We found new associations between anti-HCV prevalence and gravidity and obesity. Recently discovered genetic factors may underlie differences in HCV RNA clearance in black donors.