Iron-deficient erythropoiesis in blood donors and red blood cell recovery after transfusion: initial studies with a mouse model

Dietary iron deficiency impairs effector function of memory T cells following influenza infection

The establishment of memory T cell responses is critical to protection against pathogens and is influenced by the conditions under which memory formation occurs. Iron is an essential micronutrient for multiple immunologic processes and nutritional deficiency is a common problem worldwide. Despite its prevalence, the impact of nutritional iron deficiency on the establishment of memory T cell responses is not fully understood. In this study we investigate the impact of nutritional iron deficiency on the generation, phenotype, and function of memory T cell responses using a murine model of dietary iron modulation in the context of influenza infection. Iron deficient mice have decreased systemic iron levels and develop significant anemia. Increased T cell expression of the transferrin receptor (CD71) is seen in iron deficient mice at baseline. During primary influenza infection, iron deficient mice experience increased weight loss and phenotypic evidence of impairments in T cell activation. Following recovery from infection, iron deficient mice generate increased influenza specific memory T cells which exhibit impaired ability to produce IFNγ, most notably within the lung. Importantly, the ability to produce IFNγ and TNFα is not recovered by co-culture with iron replete dendritic cells, suggesting a T cell intrinsic alteration in functional memory formation. Altogether, these results isolate a critical effect of nutritional iron deficiency on T cell memory development and function.

Associations of donor, component, and recipient factors on hemoglobin increments following red blood cell transfusion in very low birth weight infants

BACKGROUND

Anemia in very low birth weight (VLBW) infants is common and frequently managed with red blood cell (RBC) transfusions. We utilized a linked vein-to-vein database to assess the role of blood donors and component factors on measures of RBC transfusion effectiveness in VLBW infants.

STUDY DESIGN AND METHODS

We linked blood donor and component manufacturing data with VLBW infants transfused RBCs between January 1, 2013 and December 31, 2016 in the Recipient Epidemiology Donor Evaluation Study-III (REDS III) database. Using multivariable regression, hemoglobin increments and subsequent transfusion events following single-unit RBC transfusion episodes were examined with consideration of donor, component, and recipient factors.

RESULTS

Data on VLBW infants (n = 254) who received one or more single-unit RBC transfusions (n = 567 units) were linked to donor demographic and component manufacturing characteristics for analysis. Reduced post-transfusion hemoglobin increments were associated with RBC units donated by female donors (-0.24 g/dL [95% confidence interval (CI) -0.57, -0.02]; p = .04) and donors <25 years old (-0.57 g/dL [95% CI -1.02, -0.11]; p = .02). For RBC units donated by male donors, reduced donor hemoglobin levels were associated with an increased need for subsequent recipient RBC transfusion (odds ratio 3.0 [95% CI 1.3, 6.7]; p < .01). In contrast, component characteristics, storage duration, and time from irradiation to transfusion were not associated with post-transfusion hemoglobin increments.

CONCLUSION

Donor sex, age, and hemoglobin levels were associated with measures of RBC transfusion effectiveness in VLBW infants. Mechanistic studies are needed to better understand the role of these potential donor factors on other clinical outcomes in VLBW infants.

Reticulocytes in donor RBC units enhance RBC alloimmunization

Although red blood cell (RBC) transfusions save lives, some patients develop clinically-significant alloantibodies against donor blood group antigens, which then have adverse effects in multiple clinical settings. Few effective measures exist to prevent RBC alloimmunization and/or eliminate alloantibodies in sensitized patients. Donor-related factors may influence alloimmunization; thus, there is an unmet clinical need to identify which RBC units are immunogenic. Repeat volunteer blood donors and donors on iron supplements have elevated reticulocyte counts compared to healthy non-donors. Early reticulocytes retain mitochondria and other components, which may act as danger signals in immune responses. Herein, we tested whether reticulocytes in donor RBC units could enhance RBC alloimmunization. Using a murine model, we demonstrate that transfusing donor RBC units with increased reticulocyte frequencies dose-dependently increase RBC alloimmunization rates and alloantibody levels. Transfusing reticulocyte-rich RBC units was associated with increased RBC clearance from the circulation and a robust proinflammatory cytokine response. As compared to previously reported post-transfusion RBC consumption patterns, erythrophagocytosis from reticulocyte-rich units was increasingly performed by splenic B cells. These data suggest that reticulocytes in a donated RBC unit impact the quality of blood transfused, are targeted to a distinct compartment, and may be an underappreciated risk factor for RBC alloimmunization.

Current Understanding of the Relationship between Blood Donor Variability and Blood Component Quality

While differences among donors has long challenged meeting quality standards for the production of blood components for transfusion, only recently has the molecular basis for many of these differences become understood. This review article will examine our current understanding of the molecular differences that impact the quality of red blood cells (RBC), platelets, and plasma components. Factors affecting RBC quality include cytoskeletal elements and membrane proteins associated with the oxidative response as well as known enzyme polymorphisms and hemoglobin variants. Donor age and health status may also be important. Platelet quality is impacted by variables that are less well understood, but that include platelet storage sensitive metabolic parameters, responsiveness to agonists accumulating in storage containers and factors affecting the maintenance of pH. An increased understanding of these variables can be used to improve the quality of blood components for transfusion by using donor management algorithms based on a donors individual molecular and genetic profile.

Spatial variations and determinants of anemia among under-five children in Ethiopia, EDHS 2005-2016

BACKGROUND

Anemia has severe public health significance in sub-Saharan Africa. In Ethiopia, anemia has been increasing in the last two decades, reaching the highest national level in 2016, however, the geospatial distribution and determinants of anemia in children weren't well explored at a national level.

METHODS

We used the Ethiopian Demographic and Health Survey(EDHS) data from 2005-2016. The data consists of samples of households (HHs) obtained through a two-stage stratified sampling procedure. Our analysis included 19,699 children. Descriptive statistics, geospatial analysis, and Generalized Linear Mixed Model (GLMMs) were used.

RESULTS

The overall prevalence of anemia was 51.5%; the spatial distribution of anemia significantly different across clusters in each survey. Children from 6 to 11 months had higher odds of anemia compared to 24-59 months (Adjusted Odds ratio (AOR) = 3.4, 95%Confidence level (CI): 2.99-3.76). Children with the first and second birth order were less likely to be anemic compared to fifth and above (AOR = 0.60, 95%CI: 0.38-0.95, and AOR = 0.83, 95%C: 0.73-0.93) respectively. Mothers' age 15 to 24 years was associated with higher odds of anemia compared to 35 to 49 years (AOR = 1.37, 95%CI: 1.20-1.55). Children from HHs with the poorest and poorer wealth category showed a higher odds of anemia compared to the richest (AOR = 1.67, 95%CI: 1.45-1.93, and AOR = 1.25, 95%CI: 1.08-1.45) respectively. Moreover, children from HHs with one to two under-five children were less likely to be anemic compared to those three and more (AOR = 0.83, 95%CI: 0.76-0.91).

CONCLUSIONS

The geospatial distribution of anemia among children varies in Ethiopia; it was highest in the East, Northeast, and Western regions of the country. Several factors were associated with anemia; therefore, interventions targeting the hotspots areas and specific determinant factors should be implemented by the concerned bodies to reduce the consequences of anemia on the generation.

Long-Term Course of Haemoglobin and Ferritin Values in High-Frequency Donors of Whole Blood and Double Erythrocyte Apheresis

Background

High-intensity donation is a risk factor for iron deficiency in blood donors. Interdonation intervals for whole blood (WB) donation and double unit red blood cell apheresis (2RBC) vary among countries. We retrospectively evaluated the course of haemoglobin (Hb) and ferritin values in men regularly donating WB 4 times a year or 2RBC twice a year (i.e., maximal frequency) over a period of 48 months.

Methods

Data of male donors with 16 WB or 8 2RBC consecutive donations were analysed. The minimum Hb levels for WB donation and 2RBC apheresis (collection of 360 mL RBC) were 135 and 140 g/L, respectively. There was no lower limit set for ferritin, and no iron was substituted.

Results

We identified 294 WB (mean age 53 years, SD 11) and 151 2RBC donors (mean age 48 years, SD 9) who donated at a mean interval of 97 (SD 18) and 201 days (SD 32), respectively, between January 1, 2008, and December 31, 2013. At baseline, Hb and ferritin values were lower in WB donors compared to 2RBC donors, with a mean Hb of 153 g/L (SD 13) versus 159 g/L (SD 8) and a mean ferritin of 44 μg/L (SD 52) versus 73 μg/L (SD 56; p < 0.001 for both parameters), respectively. Ferritin was below 15 μg/L in 40 WB (14%) and in 4 (3%) 2RBC donors. In WB donors, the mean Hb levels at baseline versus last donation showed no significant difference (153 vs. 152 g/L, p = 0.068), whereas the mean ferritin levels decreased significantly (44 vs. 35 μg/L, p < 0.001). The 2RBC donor group displayed a statistically different decrease in both the mean Hb levels (158 vs. 157 g/L; p < 0.05) and the mean ferritin levels (73 vs. 66 μg/L; p = 0.052). The lowest Hb was measured at the 11th WB donation (152 g/L; p < 0.05) and at the 4th 2RBC apheresis (157 g/L; p < 0.05). There was no deferral due to low Hb at any time. The lowest ferritin was shown at the 4th WB (37 μg/L) and at the 3rd 2RBC donation (60 μg/L), respectively. At the last visit, ferritin was below 15 μg/L in 23 WB donors (8%) and in 2 2RBC donors (1%).

Conclusions

High-intensity male donors with an interdonation interval of 12 weeks for WB donation and 24 weeks for 2RBC apheresis maintain acceptable Hb levels and, after an initial decline, stable ferritin levels despite ongoing blood donation.

Quantification of the Mean and Distribution of Hemoglobin Content in Normal Human Blood Using Cell Tracking Velocimetry

The current clinical method for detecting anemia focuses on measuring the concentration of hemoglobin (Hb) in blood. However, recent developments in particle tracking algorithms and the understanding of the relationship between Hb and magnetism has enabled the quantitative measurement of the Hb content in a single red blood cell, RBC, based on magnetophoretic mobility. To further explore this relationship, 22 human blood samples obtained from 17 healthy volunteers were analyzed by the cell tracking velocimetry system, and the calculated Hb concentration from these measurements was compared to the values measured by UV-visible spectrophotometry, the standard method for measuring Hb in clinical laboratories. The results show close correlations between the mean of the spectrophotometric and magnetophoretic methods; however, single cell analysis with the magnetophoretic mobility method allows further elucidation of the distribution of Hb concentration within RBCs from a donor sample to be determined. Histograms of these magnetophoretic mobility distributions indicate that the fraction of RBCs that are below the bulk Hb concentration that defines anemia varies not only from donor to donor but also in the same donor over time. Consistent with a variable fraction below the anemic Hb concentration, the distribution around the mean has a large range. Previous studies have indicated that RBCs lose Hb during ex vivo storage; however, it is not known if this variability in the distribution of Hb content is a function of the age of the RBCs in a donor, suggesting a variable rate in RBC production between donors, or variability in available iron at the time of RBC formation. We suggest our cell tracking velocimetry system can reveal more information regarding this matter.

Association of donor age, body mass index, hemoglobin, and smoking status with in-hospital mortality and length of stay among red blood cell-transfused recipients

BACKGROUND

Recent publications have reported conflicting findings regarding associations of blood donor demographics and mortality of transfused patients. We hypothesized that the analysis of additional donor characteristics and consideration of alternative outcomes might provide insight into these disparate results.

STUDY DESIGN AND METHODS

We analyzed data from a retrospective cohort of transfused patients from the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III). We used stratified Cox regression models to estimate associations between blood donor characteristics and hospital mortality and posttransfusion length of stay among patients transfused red blood cell (RBC) units. Donor characteristics evaluated included age, body mass index, hemoglobin levels, and smoking status. The statistical analyses were adjusted for recipient factors, including total number of transfusions.

RESULTS

We studied 93,726 patients in 130,381 hospitalizations during which 428,461 RBC units were transfused. There were no associations between blood donor characteristics and hospital mortality. Receipt of RBC units from donors less than 20 years of age was associated with a shorter hospital length of stay (hazard ratio for discharge per transfused unit, 1.03; 95% confidence interval, 1.02-1.04; p < 0.001) but not for other donor characteristics.

CONCLUSION

We found no evidence of associations between blood donor factors and in-hospital mortality. Our finding of shorter hospital length of stay in patients transfused RBCs from younger donors is intriguing but requires confirmation. Future collaborations are needed to develop a framework of appropriate methodologic approaches to be used in linked analyses across large cohorts.

Effect of donor, component, and recipient characteristics on hemoglobin increments following red blood cell transfusion

Significant research has focused individually on blood donors, product preparation and storage, and optimal transfusion practice. To better understand the interplay between these factors on measures of red blood cell (RBC) transfusion efficacy, we conducted a linked analysis of blood donor and component data with patients who received single-unit RBC transfusions between 2008 and 2016. Hemoglobin levels before and after RBC transfusions and at 24- and 48-hour intervals after transfusion were analyzed. Generalized estimating equation linear regression models were fit to examine hemoglobin increments after RBC transfusion adjusting for donor and recipient demographic characteristics, collection method, additive solution, gamma irradiation, and storage duration. We linked data on 23 194 transfusion recipients who received one or more single-unit RBC transfusions (n = 38 019 units) to donor demographic and component characteristics. Donor and recipient sex, Rh-D status, collection method, gamma irradiation, recipient age and body mass index, and pretransfusion hemoglobin levels were significant predictors of hemoglobin increments in univariate and multivariable analyses (P < .01). For hemoglobin increments 24 hours after transfusion, the coefficient of determination for the generalized estimating equation models was 0.25, with an estimated correlation between actual and predicted values of 0.5. Collectively, blood donor demographic characteristics, collection and processing methods, and recipient characteristics accounted for significant variation in hemoglobin increments related to RBC transfusion. Multivariable modeling allows the prediction of changes in hemoglobin using donor-, component-, and patient-level characteristics. Accounting for these factors will be critical for future analyses of donor and component factors, including genetic polymorphisms, on posttransfusion increments and other patient outcomes.

Donor Iron Deficiency Study (DIDS): protocol of a study to test whether iron deficiency in blood donors affects red blood cell recovery after transfusion

BACKGROUND

Despite fulfilling all requirements for blood donation, a large proportion of regular blood donors are iron deficient. Red blood cells (RBC) from iron-deficient donors may be particularly susceptible to damage induced by standard refrigerated storage. Herein, we present a study protocol for testing whether correcting iron deficiency in donors with iron-deficient erythropoiesis will improve the quality of their refrigerator-stored RBC.

MATERIALS AND METHODS

This is a randomised, controlled, double-blind clinical trial. Sixty healthy regular donors who meet donation standards, while exhibiting iron-deficient erythropoiesis by laboratory testing criteria, will donate a single standard RBC unit that will be leucoreduced and stored in a refrigerator under standard conditions for 40-42 days. A 51Cr-radiolabelled 24-hour RBC recovery study will be performed and then these donors will be randomised to receive, in a double-blinded fashion, either intravenous saline, as a control, or low-molecular weight iron dextran (1 g), to provide total iron repletion. Four to six months later, they will donate a second RBC unit, which will be similarly stored, and autologous 51Cr-labelled 24-hour post-transfusion RBC recovery will again be determined.

RESULTS

The primary endpoint will be the change in 24-hour post-transfusion recovery from the first to the second donation. The primary outcome will be the group mean difference in the primary endpoints between the group receiving intravenous saline and the group receiving intravenous iron dextran. Secondary outcomes will be quality of life, fatigue, and emotional health, assessed by surveys.

CONCLUSION

This study will provide definitive evidence as to whether donor iron deficiency affects the quality of the blood supply and will assess the severity of symptoms affecting iron-deficient blood donors.

Frequent blood donations alter susceptibility of red blood cells to storage- and stress-induced hemolysis

BACKGROUND

Frequent whole blood donations increase the prevalence of iron depletion in blood donors, which may subsequently interfere with normal erythropoiesis. The purpose of this study was to evaluate the associations between donation frequency and red blood cell (RBC) storage stability in a racially/ethnically diverse population of blood donors.

STUDY DESIGN

Leukoreduced RBC concentrate-derived samples from 13,403 donors were stored for 39 to 42 days (1-6°C) and then evaluated for storage, osmotic, and oxidative hemolysis. Iron status was evaluated by plasma ferritin measurement and self-reported intake of iron supplements. Donation history in the prior 2 years was obtained for each subject.

RESULTS

Frequent blood donors enrolled in this study were likely to be white, male, and of older age (56.1 ± 5.0 years). Prior donation intensity was negatively associated with oxidative hemolysis (p < 0.0001) in multivariate analyses correcting for age, sex, and race/ethnicity. Increased plasma ferritin concentration was associated with increased RBC susceptibility to each of the three measures of hemolysis (p < 0.0001 for all), whereas self-reported iron intake was associated with reduced susceptibility to osmotic and oxidative hemolysis (p < 0.0001 for both).

CONCLUSIONS

Frequent blood donations may alter the quality of blood components by modulating RBC predisposition to hemolysis. RBCs collected from frequent donors with low ferritin have altered susceptibility to hemolysis. Thus, frequent donation and associated iron loss may alter the quality of stored RBC components collected from iron-deficient donors. Further investigation is necessary to assess posttransfusion safety and efficacy in patients receiving these RBC products.

Association of Blood Transfusion From Female Donors With and Without a History of Pregnancy With Mortality Among Male and Female Transfusion Recipients

IMPORTANCE

Transfusion of red blood cells from female donors has been associated with increased mortality in male recipients.

OBJECTIVE

To quantify the association between red blood cell transfusion from female donors with and without a history of pregnancy and mortality of red blood cell recipients.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of first-time transfusion recipients at 6 major Dutch hospitals enrolled from May 30, 2005, to September 1, 2015; the final follow-up date was September 1, 2015. The primary analysis was the no-donor-mixture cohort (ie, either all red blood cell transfusions exclusively from male donors, or all exclusively from female donors without a history of pregnancy, or all exclusively from female donors with a history of pregnancy). The association between mortality and exposure to transfusions from ever-pregnant or never-pregnant female donors was analyzed using life tables and time-varying Cox proportional hazards models.

EXPOSURES

Red blood cell transfusions from ever-pregnant or never-pregnant female donors, compared with red blood cell transfusions from male donors.

MAIN OUTCOMES AND MEASURES

All-cause mortality during follow-up.

RESULTS

The cohort for the primary analyses consisted of 31 118 patients (median age, 65 [interquartile range, 42-77] years; 52% female) who received 59 320 red blood cell transfusions exclusively from 1 of 3 types of donors (88% male; 6% ever-pregnant female; and 6% never-pregnant female). The number of deaths in this cohort was 3969 (13% mortality). For male recipients of red blood cell transfusions, all-cause mortality rates after a red blood cell transfusion from an ever-pregnant female donor vs male donor were 101 vs 80 deaths per 1000 person-years (time-dependent "per transfusion" hazard ratio [HR] for death, 1.13 [95% CI, 1.01-1.26]). For receipt of transfusion from a never-pregnant female donor vs male donor, mortality rates were 78 vs 80 deaths per 1000 person-years (HR, 0.93 [95% CI, 0.81-1.06]). Among female recipients of red blood cell transfusions, mortality rates for an ever-pregnant female donor vs male donor were 74 vs 62 per 1000 person-years (HR, 0.99 [95% CI, 0.87 to 1.13]); for a never-pregnant female donor vs male donor, mortality rates were 74 vs 62 per 1000 person-years (HR, 1.01 [95% CI, 0.88-1.15]).

CONCLUSIONS AND RELEVANCE

Among patients who received red blood cell transfusions, receipt of a transfusion from an ever-pregnant female donor, compared with a male donor, was associated with increased all-cause mortality among male recipients but not among female recipients. Transfusions from never-pregnant female donors were not associated with increased mortality among male or female recipients. Further research is needed to replicate these findings, determine their clinical significance, and identify the underlying mechanism.